/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2009-2012 Spectra Logic Corporation * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions, and the following disclaimer, * without modification. * 2. Redistributions in binary form must reproduce at minimum a disclaimer * substantially similar to the "NO WARRANTY" disclaimer below * ("Disclaimer") and any redistribution must be conditioned upon * including a substantially similar Disclaimer requirement for further * binary redistribution. * * NO WARRANTY * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGES. * * Authors: Justin T. Gibbs (Spectra Logic Corporation) * Ken Merry (Spectra Logic Corporation) */ #include __FBSDID("$FreeBSD$"); /** * \file blkback.c * * \brief Device driver supporting the vending of block storage from * a FreeBSD domain to other domains. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /*--------------------------- Compile-time Tunables --------------------------*/ /** * The maximum number of shared memory ring pages we will allow in a * negotiated block-front/back communication channel. Allow enough * ring space for all requests to be XBB_MAX_REQUEST_SIZE'd. */ #define XBB_MAX_RING_PAGES 32 /** * The maximum number of outstanding request blocks (request headers plus * additional segment blocks) we will allow in a negotiated block-front/back * communication channel. */ #define XBB_MAX_REQUESTS \ __CONST_RING_SIZE(blkif, PAGE_SIZE * XBB_MAX_RING_PAGES) /** * \brief Define to force all I/O to be performed on memory owned by the * backend device, with a copy-in/out to the remote domain's memory. * * \note This option is currently required when this driver's domain is * operating in HVM mode on a system using an IOMMU. * * This driver uses Xen's grant table API to gain access to the memory of * the remote domains it serves. When our domain is operating in PV mode, * the grant table mechanism directly updates our domain's page table entries * to point to the physical pages of the remote domain. This scheme guarantees * that blkback and the backing devices it uses can safely perform DMA * operations to satisfy requests. In HVM mode, Xen may use a HW IOMMU to * insure that our domain cannot DMA to pages owned by another domain. As * of Xen 4.0, IOMMU mappings for HVM guests are not updated via the grant * table API. For this reason, in HVM mode, we must bounce all requests into * memory that is mapped into our domain at domain startup and thus has * valid IOMMU mappings. */ #define XBB_USE_BOUNCE_BUFFERS /** * \brief Define to enable rudimentary request logging to the console. */ #undef XBB_DEBUG /*---------------------------------- Macros ----------------------------------*/ /** * Custom malloc type for all driver allocations. */ static MALLOC_DEFINE(M_XENBLOCKBACK, "xbbd", "Xen Block Back Driver Data"); #ifdef XBB_DEBUG #define DPRINTF(fmt, args...) \ printf("xbb(%s:%d): " fmt, __FUNCTION__, __LINE__, ##args) #else #define DPRINTF(fmt, args...) do {} while(0) #endif /** * The maximum mapped region size per request we will allow in a negotiated * block-front/back communication channel. * Use old default of MAXPHYS == 128K. */ #define XBB_MAX_REQUEST_SIZE \ MIN(128 * 1024, BLKIF_MAX_SEGMENTS_PER_REQUEST * PAGE_SIZE) /** * The maximum number of segments (within a request header and accompanying * segment blocks) per request we will allow in a negotiated block-front/back * communication channel. */ #define XBB_MAX_SEGMENTS_PER_REQUEST \ (MIN(UIO_MAXIOV, \ MIN(BLKIF_MAX_SEGMENTS_PER_REQUEST, \ (XBB_MAX_REQUEST_SIZE / PAGE_SIZE) + 1))) /** * The maximum number of ring pages that we can allow per request list. * We limit this to the maximum number of segments per request, because * that is already a reasonable number of segments to aggregate. This * number should never be smaller than XBB_MAX_SEGMENTS_PER_REQUEST, * because that would leave situations where we can't dispatch even one * large request. */ #define XBB_MAX_SEGMENTS_PER_REQLIST XBB_MAX_SEGMENTS_PER_REQUEST /*--------------------------- Forward Declarations ---------------------------*/ struct xbb_softc; struct xbb_xen_req; static void xbb_attach_failed(struct xbb_softc *xbb, int err, const char *fmt, ...) __attribute__((format(printf, 3, 4))); static int xbb_shutdown(struct xbb_softc *xbb); /*------------------------------ Data Structures -----------------------------*/ STAILQ_HEAD(xbb_xen_req_list, xbb_xen_req); typedef enum { XBB_REQLIST_NONE = 0x00, XBB_REQLIST_MAPPED = 0x01 } xbb_reqlist_flags; struct xbb_xen_reqlist { /** * Back reference to the parent block back instance for this * request. Used during bio_done handling. */ struct xbb_softc *xbb; /** * BLKIF_OP code for this request. */ int operation; /** * Set to BLKIF_RSP_* to indicate request status. * * This field allows an error status to be recorded even if the * delivery of this status must be deferred. Deferred reporting * is necessary, for example, when an error is detected during * completion processing of one bio when other bios for this * request are still outstanding. */ int status; /** * Number of 512 byte sectors not transferred. */ int residual_512b_sectors; /** * Starting sector number of the first request in the list. */ off_t starting_sector_number; /** * If we're going to coalesce, the next contiguous sector would be * this one. */ off_t next_contig_sector; /** * Number of child requests in the list. */ int num_children; /** * Number of I/O requests still pending on the backend. */ int pendcnt; /** * Total number of segments for requests in the list. */ int nr_segments; /** * Flags for this particular request list. */ xbb_reqlist_flags flags; /** * Kernel virtual address space reserved for this request * list structure and used to map the remote domain's pages for * this I/O, into our domain's address space. */ uint8_t *kva; /** * Base, pseudo-physical address, corresponding to the start * of this request's kva region. */ uint64_t gnt_base; #ifdef XBB_USE_BOUNCE_BUFFERS /** * Pre-allocated domain local memory used to proxy remote * domain memory during I/O operations. */ uint8_t *bounce; #endif /** * Array of grant handles (one per page) used to map this request. */ grant_handle_t *gnt_handles; /** * Device statistics request ordering type (ordered or simple). */ devstat_tag_type ds_tag_type; /** * Device statistics request type (read, write, no_data). */ devstat_trans_flags ds_trans_type; /** * The start time for this request. */ struct bintime ds_t0; /** * Linked list of contiguous requests with the same operation type. */ struct xbb_xen_req_list contig_req_list; /** * Linked list links used to aggregate idle requests in the * request list free pool (xbb->reqlist_free_stailq) and pending * requests waiting for execution (xbb->reqlist_pending_stailq). */ STAILQ_ENTRY(xbb_xen_reqlist) links; }; STAILQ_HEAD(xbb_xen_reqlist_list, xbb_xen_reqlist); /** * \brief Object tracking an in-flight I/O from a Xen VBD consumer. */ struct xbb_xen_req { /** * Linked list links used to aggregate requests into a reqlist * and to store them in the request free pool. */ STAILQ_ENTRY(xbb_xen_req) links; /** * The remote domain's identifier for this I/O request. */ uint64_t id; /** * The number of pages currently mapped for this request. */ int nr_pages; /** * The number of 512 byte sectors comprising this requests. */ int nr_512b_sectors; /** * BLKIF_OP code for this request. */ int operation; /** * Storage used for non-native ring requests. */ blkif_request_t ring_req_storage; /** * Pointer to the Xen request in the ring. */ blkif_request_t *ring_req; /** * Consumer index for this request. */ RING_IDX req_ring_idx; /** * The start time for this request. */ struct bintime ds_t0; /** * Pointer back to our parent request list. */ struct xbb_xen_reqlist *reqlist; }; SLIST_HEAD(xbb_xen_req_slist, xbb_xen_req); /** * \brief Configuration data for the shared memory request ring * used to communicate with the front-end client of this * this driver. */ struct xbb_ring_config { /** KVA address where ring memory is mapped. */ vm_offset_t va; /** The pseudo-physical address where ring memory is mapped.*/ uint64_t gnt_addr; /** * Grant table handles, one per-ring page, returned by the * hyperpervisor upon mapping of the ring and required to * unmap it when a connection is torn down. */ grant_handle_t handle[XBB_MAX_RING_PAGES]; /** * The device bus address returned by the hypervisor when * mapping the ring and required to unmap it when a connection * is torn down. */ uint64_t bus_addr[XBB_MAX_RING_PAGES]; /** The number of ring pages mapped for the current connection. */ u_int ring_pages; /** * The grant references, one per-ring page, supplied by the * front-end, allowing us to reference the ring pages in the * front-end's domain and to map these pages into our own domain. */ grant_ref_t ring_ref[XBB_MAX_RING_PAGES]; /** The interrupt driven even channel used to signal ring events. */ evtchn_port_t evtchn; }; /** * Per-instance connection state flags. */ typedef enum { /** * The front-end requested a read-only mount of the * back-end device/file. */ XBBF_READ_ONLY = 0x01, /** Communication with the front-end has been established. */ XBBF_RING_CONNECTED = 0x02, /** * Front-end requests exist in the ring and are waiting for * xbb_xen_req objects to free up. */ XBBF_RESOURCE_SHORTAGE = 0x04, /** Connection teardown in progress. */ XBBF_SHUTDOWN = 0x08, /** A thread is already performing shutdown processing. */ XBBF_IN_SHUTDOWN = 0x10 } xbb_flag_t; /** Backend device type. */ typedef enum { /** Backend type unknown. */ XBB_TYPE_NONE = 0x00, /** * Backend type disk (access via cdev switch * strategy routine). */ XBB_TYPE_DISK = 0x01, /** Backend type file (access vnode operations.). */ XBB_TYPE_FILE = 0x02 } xbb_type; /** * \brief Structure used to memoize information about a per-request * scatter-gather list. * * The chief benefit of using this data structure is it avoids having * to reparse the possibly discontiguous S/G list in the original * request. Due to the way that the mapping of the memory backing an * I/O transaction is handled by Xen, a second pass is unavoidable. * At least this way the second walk is a simple array traversal. * * \note A single Scatter/Gather element in the block interface covers * at most 1 machine page. In this context a sector (blkif * nomenclature, not what I'd choose) is a 512b aligned unit * of mapping within the machine page referenced by an S/G * element. */ struct xbb_sg { /** The number of 512b data chunks mapped in this S/G element. */ int16_t nsect; /** * The index (0 based) of the first 512b data chunk mapped * in this S/G element. */ uint8_t first_sect; /** * The index (0 based) of the last 512b data chunk mapped * in this S/G element. */ uint8_t last_sect; }; /** * Character device backend specific configuration data. */ struct xbb_dev_data { /** Cdev used for device backend access. */ struct cdev *cdev; /** Cdev switch used for device backend access. */ struct cdevsw *csw; /** Used to hold a reference on opened cdev backend devices. */ int dev_ref; }; /** * File backend specific configuration data. */ struct xbb_file_data { /** Credentials to use for vnode backed (file based) I/O. */ struct ucred *cred; /** * \brief Array of io vectors used to process file based I/O. * * Only a single file based request is outstanding per-xbb instance, * so we only need one of these. */ struct iovec xiovecs[XBB_MAX_SEGMENTS_PER_REQLIST]; #ifdef XBB_USE_BOUNCE_BUFFERS /** * \brief Array of io vectors used to handle bouncing of file reads. * * Vnode operations are free to modify uio data during their * exectuion. In the case of a read with bounce buffering active, * we need some of the data from the original uio in order to * bounce-out the read data. This array serves as the temporary * storage for this saved data. */ struct iovec saved_xiovecs[XBB_MAX_SEGMENTS_PER_REQLIST]; /** * \brief Array of memoized bounce buffer kva offsets used * in the file based backend. * * Due to the way that the mapping of the memory backing an * I/O transaction is handled by Xen, a second pass through * the request sg elements is unavoidable. We memoize the computed * bounce address here to reduce the cost of the second walk. */ void *xiovecs_vaddr[XBB_MAX_SEGMENTS_PER_REQLIST]; #endif /* XBB_USE_BOUNCE_BUFFERS */ }; /** * Collection of backend type specific data. */ union xbb_backend_data { struct xbb_dev_data dev; struct xbb_file_data file; }; /** * Function signature of backend specific I/O handlers. */ typedef int (*xbb_dispatch_t)(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist, int operation, int flags); /** * Per-instance configuration data. */ struct xbb_softc { /** * Task-queue used to process I/O requests. */ struct taskqueue *io_taskqueue; /** * Single "run the request queue" task enqueued * on io_taskqueue. */ struct task io_task; /** Device type for this instance. */ xbb_type device_type; /** NewBus device corresponding to this instance. */ device_t dev; /** Backend specific dispatch routine for this instance. */ xbb_dispatch_t dispatch_io; /** The number of requests outstanding on the backend device/file. */ int active_request_count; /** Free pool of request tracking structures. */ struct xbb_xen_req_list request_free_stailq; /** Array, sized at connection time, of request tracking structures. */ struct xbb_xen_req *requests; /** Free pool of request list structures. */ struct xbb_xen_reqlist_list reqlist_free_stailq; /** List of pending request lists awaiting execution. */ struct xbb_xen_reqlist_list reqlist_pending_stailq; /** Array, sized at connection time, of request list structures. */ struct xbb_xen_reqlist *request_lists; /** * Global pool of kva used for mapping remote domain ring * and I/O transaction data. */ vm_offset_t kva; /** Pseudo-physical address corresponding to kva. */ uint64_t gnt_base_addr; /** The size of the global kva pool. */ int kva_size; /** The size of the KVA area used for request lists. */ int reqlist_kva_size; /** The number of pages of KVA used for request lists */ int reqlist_kva_pages; /** Bitmap of free KVA pages */ bitstr_t *kva_free; /** * \brief Cached value of the front-end's domain id. * * This value is used at once for each mapped page in * a transaction. We cache it to avoid incuring the * cost of an ivar access every time this is needed. */ domid_t otherend_id; /** * \brief The blkif protocol abi in effect. * * There are situations where the back and front ends can * have a different, native abi (e.g. intel x86_64 and * 32bit x86 domains on the same machine). The back-end * always accommodates the front-end's native abi. That * value is pulled from the XenStore and recorded here. */ int abi; /** * \brief The maximum number of requests and request lists allowed * to be in flight at a time. * * This value is negotiated via the XenStore. */ u_int max_requests; /** * \brief The maximum number of segments (1 page per segment) * that can be mapped by a request. * * This value is negotiated via the XenStore. */ u_int max_request_segments; /** * \brief Maximum number of segments per request list. * * This value is derived from and will generally be larger than * max_request_segments. */ u_int max_reqlist_segments; /** * The maximum size of any request to this back-end * device. * * This value is negotiated via the XenStore. */ u_int max_request_size; /** * The maximum size of any request list. This is derived directly * from max_reqlist_segments. */ u_int max_reqlist_size; /** Various configuration and state bit flags. */ xbb_flag_t flags; /** Ring mapping and interrupt configuration data. */ struct xbb_ring_config ring_config; /** Runtime, cross-abi safe, structures for ring access. */ blkif_back_rings_t rings; /** IRQ mapping for the communication ring event channel. */ xen_intr_handle_t xen_intr_handle; /** * \brief Backend access mode flags (e.g. write, or read-only). * * This value is passed to us by the front-end via the XenStore. */ char *dev_mode; /** * \brief Backend device type (e.g. "disk", "cdrom", "floppy"). * * This value is passed to us by the front-end via the XenStore. * Currently unused. */ char *dev_type; /** * \brief Backend device/file identifier. * * This value is passed to us by the front-end via the XenStore. * We expect this to be a POSIX path indicating the file or * device to open. */ char *dev_name; /** * Vnode corresponding to the backend device node or file * we are acessing. */ struct vnode *vn; union xbb_backend_data backend; /** The native sector size of the backend. */ u_int sector_size; /** log2 of sector_size. */ u_int sector_size_shift; /** Size in bytes of the backend device or file. */ off_t media_size; /** * \brief media_size expressed in terms of the backend native * sector size. * * (e.g. xbb->media_size >> xbb->sector_size_shift). */ uint64_t media_num_sectors; /** * \brief Array of memoized scatter gather data computed during the * conversion of blkif ring requests to internal xbb_xen_req * structures. * * Ring processing is serialized so we only need one of these. */ struct xbb_sg xbb_sgs[XBB_MAX_SEGMENTS_PER_REQLIST]; /** * Temporary grant table map used in xbb_dispatch_io(). When * XBB_MAX_SEGMENTS_PER_REQLIST gets large, keeping this on the * stack could cause a stack overflow. */ struct gnttab_map_grant_ref maps[XBB_MAX_SEGMENTS_PER_REQLIST]; /** Mutex protecting per-instance data. */ struct mtx lock; /** * Resource representing allocated physical address space * associated with our per-instance kva region. */ struct resource *pseudo_phys_res; /** Resource id for allocated physical address space. */ int pseudo_phys_res_id; /** * I/O statistics from BlockBack dispatch down. These are * coalesced requests, and we start them right before execution. */ struct devstat *xbb_stats; /** * I/O statistics coming into BlockBack. These are the requests as * we get them from BlockFront. They are started as soon as we * receive a request, and completed when the I/O is complete. */ struct devstat *xbb_stats_in; /** Disable sending flush to the backend */ int disable_flush; /** Send a real flush for every N flush requests */ int flush_interval; /** Count of flush requests in the interval */ int flush_count; /** Don't coalesce requests if this is set */ int no_coalesce_reqs; /** Number of requests we have received */ uint64_t reqs_received; /** Number of requests we have completed*/ uint64_t reqs_completed; /** Number of requests we queued but not pushed*/ uint64_t reqs_queued_for_completion; /** Number of requests we completed with an error status*/ uint64_t reqs_completed_with_error; /** How many forced dispatches (i.e. without coalescing) have happened */ uint64_t forced_dispatch; /** How many normal dispatches have happened */ uint64_t normal_dispatch; /** How many total dispatches have happened */ uint64_t total_dispatch; /** How many times we have run out of KVA */ uint64_t kva_shortages; /** How many times we have run out of request structures */ uint64_t request_shortages; /** Watch to wait for hotplug script execution */ struct xs_watch hotplug_watch; /** Got the needed data from hotplug scripts? */ bool hotplug_done; }; /*---------------------------- Request Processing ----------------------------*/ /** * Allocate an internal transaction tracking structure from the free pool. * * \param xbb Per-instance xbb configuration structure. * * \return On success, a pointer to the allocated xbb_xen_req structure. * Otherwise NULL. */ static inline struct xbb_xen_req * xbb_get_req(struct xbb_softc *xbb) { struct xbb_xen_req *req; req = NULL; mtx_assert(&xbb->lock, MA_OWNED); if ((req = STAILQ_FIRST(&xbb->request_free_stailq)) != NULL) { STAILQ_REMOVE_HEAD(&xbb->request_free_stailq, links); xbb->active_request_count++; } return (req); } /** * Return an allocated transaction tracking structure to the free pool. * * \param xbb Per-instance xbb configuration structure. * \param req The request structure to free. */ static inline void xbb_release_req(struct xbb_softc *xbb, struct xbb_xen_req *req) { mtx_assert(&xbb->lock, MA_OWNED); STAILQ_INSERT_HEAD(&xbb->request_free_stailq, req, links); xbb->active_request_count--; KASSERT(xbb->active_request_count >= 0, ("xbb_release_req: negative active count")); } /** * Return an xbb_xen_req_list of allocated xbb_xen_reqs to the free pool. * * \param xbb Per-instance xbb configuration structure. * \param req_list The list of requests to free. * \param nreqs The number of items in the list. */ static inline void xbb_release_reqs(struct xbb_softc *xbb, struct xbb_xen_req_list *req_list, int nreqs) { mtx_assert(&xbb->lock, MA_OWNED); STAILQ_CONCAT(&xbb->request_free_stailq, req_list); xbb->active_request_count -= nreqs; KASSERT(xbb->active_request_count >= 0, ("xbb_release_reqs: negative active count")); } /** * Given a page index and 512b sector offset within that page, * calculate an offset into a request's kva region. * * \param reqlist The request structure whose kva region will be accessed. * \param pagenr The page index used to compute the kva offset. * \param sector The 512b sector index used to compute the page relative * kva offset. * * \return The computed global KVA offset. */ static inline uint8_t * xbb_reqlist_vaddr(struct xbb_xen_reqlist *reqlist, int pagenr, int sector) { return (reqlist->kva + (PAGE_SIZE * pagenr) + (sector << 9)); } #ifdef XBB_USE_BOUNCE_BUFFERS /** * Given a page index and 512b sector offset within that page, * calculate an offset into a request's local bounce memory region. * * \param reqlist The request structure whose bounce region will be accessed. * \param pagenr The page index used to compute the bounce offset. * \param sector The 512b sector index used to compute the page relative * bounce offset. * * \return The computed global bounce buffer address. */ static inline uint8_t * xbb_reqlist_bounce_addr(struct xbb_xen_reqlist *reqlist, int pagenr, int sector) { return (reqlist->bounce + (PAGE_SIZE * pagenr) + (sector << 9)); } #endif /** * Given a page number and 512b sector offset within that page, * calculate an offset into the request's memory region that the * underlying backend device/file should use for I/O. * * \param reqlist The request structure whose I/O region will be accessed. * \param pagenr The page index used to compute the I/O offset. * \param sector The 512b sector index used to compute the page relative * I/O offset. * * \return The computed global I/O address. * * Depending on configuration, this will either be a local bounce buffer * or a pointer to the memory mapped in from the front-end domain for * this request. */ static inline uint8_t * xbb_reqlist_ioaddr(struct xbb_xen_reqlist *reqlist, int pagenr, int sector) { #ifdef XBB_USE_BOUNCE_BUFFERS return (xbb_reqlist_bounce_addr(reqlist, pagenr, sector)); #else return (xbb_reqlist_vaddr(reqlist, pagenr, sector)); #endif } /** * Given a page index and 512b sector offset within that page, calculate * an offset into the local pseudo-physical address space used to map a * front-end's request data into a request. * * \param reqlist The request list structure whose pseudo-physical region * will be accessed. * \param pagenr The page index used to compute the pseudo-physical offset. * \param sector The 512b sector index used to compute the page relative * pseudo-physical offset. * * \return The computed global pseudo-phsyical address. * * Depending on configuration, this will either be a local bounce buffer * or a pointer to the memory mapped in from the front-end domain for * this request. */ static inline uintptr_t xbb_get_gntaddr(struct xbb_xen_reqlist *reqlist, int pagenr, int sector) { struct xbb_softc *xbb; xbb = reqlist->xbb; return ((uintptr_t)(xbb->gnt_base_addr + (uintptr_t)(reqlist->kva - xbb->kva) + (PAGE_SIZE * pagenr) + (sector << 9))); } /** * Get Kernel Virtual Address space for mapping requests. * * \param xbb Per-instance xbb configuration structure. * \param nr_pages Number of pages needed. * \param check_only If set, check for free KVA but don't allocate it. * \param have_lock If set, xbb lock is already held. * * \return On success, a pointer to the allocated KVA region. Otherwise NULL. * * Note: This should be unnecessary once we have either chaining or * scatter/gather support for struct bio. At that point we'll be able to * put multiple addresses and lengths in one bio/bio chain and won't need * to map everything into one virtual segment. */ static uint8_t * xbb_get_kva(struct xbb_softc *xbb, int nr_pages) { int first_clear; int num_clear; uint8_t *free_kva; int i; KASSERT(nr_pages != 0, ("xbb_get_kva of zero length")); first_clear = 0; free_kva = NULL; mtx_lock(&xbb->lock); /* * Look for the first available page. If there are none, we're done. */ bit_ffc(xbb->kva_free, xbb->reqlist_kva_pages, &first_clear); if (first_clear == -1) goto bailout; /* * Starting at the first available page, look for consecutive free * pages that will satisfy the user's request. */ for (i = first_clear, num_clear = 0; i < xbb->reqlist_kva_pages; i++) { /* * If this is true, the page is used, so we have to reset * the number of clear pages and the first clear page * (since it pointed to a region with an insufficient number * of clear pages). */ if (bit_test(xbb->kva_free, i)) { num_clear = 0; first_clear = -1; continue; } if (first_clear == -1) first_clear = i; /* * If this is true, we've found a large enough free region * to satisfy the request. */ if (++num_clear == nr_pages) { bit_nset(xbb->kva_free, first_clear, first_clear + nr_pages - 1); free_kva = xbb->kva + (uint8_t *)((intptr_t)first_clear * PAGE_SIZE); KASSERT(free_kva >= (uint8_t *)xbb->kva && free_kva + (nr_pages * PAGE_SIZE) <= (uint8_t *)xbb->ring_config.va, ("Free KVA %p len %d out of range, " "kva = %#jx, ring VA = %#jx\n", free_kva, nr_pages * PAGE_SIZE, (uintmax_t)xbb->kva, (uintmax_t)xbb->ring_config.va)); break; } } bailout: if (free_kva == NULL) { xbb->flags |= XBBF_RESOURCE_SHORTAGE; xbb->kva_shortages++; } mtx_unlock(&xbb->lock); return (free_kva); } /** * Free allocated KVA. * * \param xbb Per-instance xbb configuration structure. * \param kva_ptr Pointer to allocated KVA region. * \param nr_pages Number of pages in the KVA region. */ static void xbb_free_kva(struct xbb_softc *xbb, uint8_t *kva_ptr, int nr_pages) { intptr_t start_page; mtx_assert(&xbb->lock, MA_OWNED); start_page = (intptr_t)(kva_ptr - xbb->kva) >> PAGE_SHIFT; bit_nclear(xbb->kva_free, start_page, start_page + nr_pages - 1); } /** * Unmap the front-end pages associated with this I/O request. * * \param req The request structure to unmap. */ static void xbb_unmap_reqlist(struct xbb_xen_reqlist *reqlist) { struct gnttab_unmap_grant_ref unmap[XBB_MAX_SEGMENTS_PER_REQLIST]; u_int i; u_int invcount; int error; invcount = 0; for (i = 0; i < reqlist->nr_segments; i++) { if (reqlist->gnt_handles[i] == GRANT_REF_INVALID) continue; unmap[invcount].host_addr = xbb_get_gntaddr(reqlist, i, 0); unmap[invcount].dev_bus_addr = 0; unmap[invcount].handle = reqlist->gnt_handles[i]; reqlist->gnt_handles[i] = GRANT_REF_INVALID; invcount++; } error = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, invcount); KASSERT(error == 0, ("Grant table operation failed")); } /** * Allocate an internal transaction tracking structure from the free pool. * * \param xbb Per-instance xbb configuration structure. * * \return On success, a pointer to the allocated xbb_xen_reqlist structure. * Otherwise NULL. */ static inline struct xbb_xen_reqlist * xbb_get_reqlist(struct xbb_softc *xbb) { struct xbb_xen_reqlist *reqlist; reqlist = NULL; mtx_assert(&xbb->lock, MA_OWNED); if ((reqlist = STAILQ_FIRST(&xbb->reqlist_free_stailq)) != NULL) { STAILQ_REMOVE_HEAD(&xbb->reqlist_free_stailq, links); reqlist->flags = XBB_REQLIST_NONE; reqlist->kva = NULL; reqlist->status = BLKIF_RSP_OKAY; reqlist->residual_512b_sectors = 0; reqlist->num_children = 0; reqlist->nr_segments = 0; STAILQ_INIT(&reqlist->contig_req_list); } return (reqlist); } /** * Return an allocated transaction tracking structure to the free pool. * * \param xbb Per-instance xbb configuration structure. * \param req The request list structure to free. * \param wakeup If set, wakeup the work thread if freeing this reqlist * during a resource shortage condition. */ static inline void xbb_release_reqlist(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist, int wakeup) { mtx_assert(&xbb->lock, MA_OWNED); if (wakeup) { wakeup = xbb->flags & XBBF_RESOURCE_SHORTAGE; xbb->flags &= ~XBBF_RESOURCE_SHORTAGE; } if (reqlist->kva != NULL) xbb_free_kva(xbb, reqlist->kva, reqlist->nr_segments); xbb_release_reqs(xbb, &reqlist->contig_req_list, reqlist->num_children); STAILQ_INSERT_TAIL(&xbb->reqlist_free_stailq, reqlist, links); if ((xbb->flags & XBBF_SHUTDOWN) != 0) { /* * Shutdown is in progress. See if we can * progress further now that one more request * has completed and been returned to the * free pool. */ xbb_shutdown(xbb); } if (wakeup != 0) taskqueue_enqueue(xbb->io_taskqueue, &xbb->io_task); } /** * Request resources and do basic request setup. * * \param xbb Per-instance xbb configuration structure. * \param reqlist Pointer to reqlist pointer. * \param ring_req Pointer to a block ring request. * \param ring_index The ring index of this request. * * \return 0 for success, non-zero for failure. */ static int xbb_get_resources(struct xbb_softc *xbb, struct xbb_xen_reqlist **reqlist, blkif_request_t *ring_req, RING_IDX ring_idx) { struct xbb_xen_reqlist *nreqlist; struct xbb_xen_req *nreq; nreqlist = NULL; nreq = NULL; mtx_lock(&xbb->lock); /* * We don't allow new resources to be allocated if we're in the * process of shutting down. */ if ((xbb->flags & XBBF_SHUTDOWN) != 0) { mtx_unlock(&xbb->lock); return (1); } /* * Allocate a reqlist if the caller doesn't have one already. */ if (*reqlist == NULL) { nreqlist = xbb_get_reqlist(xbb); if (nreqlist == NULL) goto bailout_error; } /* We always allocate a request. */ nreq = xbb_get_req(xbb); if (nreq == NULL) goto bailout_error; mtx_unlock(&xbb->lock); if (*reqlist == NULL) { *reqlist = nreqlist; nreqlist->operation = ring_req->operation; nreqlist->starting_sector_number = ring_req->sector_number; STAILQ_INSERT_TAIL(&xbb->reqlist_pending_stailq, nreqlist, links); } nreq->reqlist = *reqlist; nreq->req_ring_idx = ring_idx; nreq->id = ring_req->id; nreq->operation = ring_req->operation; if (xbb->abi != BLKIF_PROTOCOL_NATIVE) { bcopy(ring_req, &nreq->ring_req_storage, sizeof(*ring_req)); nreq->ring_req = &nreq->ring_req_storage; } else { nreq->ring_req = ring_req; } binuptime(&nreq->ds_t0); devstat_start_transaction(xbb->xbb_stats_in, &nreq->ds_t0); STAILQ_INSERT_TAIL(&(*reqlist)->contig_req_list, nreq, links); (*reqlist)->num_children++; (*reqlist)->nr_segments += ring_req->nr_segments; return (0); bailout_error: /* * We're out of resources, so set the shortage flag. The next time * a request is released, we'll try waking up the work thread to * see if we can allocate more resources. */ xbb->flags |= XBBF_RESOURCE_SHORTAGE; xbb->request_shortages++; if (nreq != NULL) xbb_release_req(xbb, nreq); if (nreqlist != NULL) xbb_release_reqlist(xbb, nreqlist, /*wakeup*/ 0); mtx_unlock(&xbb->lock); return (1); } /** * Create and queue a response to a blkif request. * * \param xbb Per-instance xbb configuration structure. * \param req The request structure to which to respond. * \param status The status code to report. See BLKIF_RSP_* * in sys/xen/interface/io/blkif.h. */ static void xbb_queue_response(struct xbb_softc *xbb, struct xbb_xen_req *req, int status) { blkif_response_t *resp; /* * The mutex is required here, and should be held across this call * until after the subsequent call to xbb_push_responses(). This * is to guarantee that another context won't queue responses and * push them while we're active. * * That could lead to the other end being notified of responses * before the resources have been freed on this end. The other end * would then be able to queue additional I/O, and we may run out * of resources because we haven't freed them all yet. */ mtx_assert(&xbb->lock, MA_OWNED); /* * Place on the response ring for the relevant domain. * For now, only the spacing between entries is different * in the different ABIs, not the response entry layout. */ switch (xbb->abi) { case BLKIF_PROTOCOL_NATIVE: resp = RING_GET_RESPONSE(&xbb->rings.native, xbb->rings.native.rsp_prod_pvt); break; case BLKIF_PROTOCOL_X86_32: resp = (blkif_response_t *) RING_GET_RESPONSE(&xbb->rings.x86_32, xbb->rings.x86_32.rsp_prod_pvt); break; case BLKIF_PROTOCOL_X86_64: resp = (blkif_response_t *) RING_GET_RESPONSE(&xbb->rings.x86_64, xbb->rings.x86_64.rsp_prod_pvt); break; default: panic("Unexpected blkif protocol ABI."); } resp->id = req->id; resp->operation = req->operation; resp->status = status; if (status != BLKIF_RSP_OKAY) xbb->reqs_completed_with_error++; xbb->rings.common.rsp_prod_pvt++; xbb->reqs_queued_for_completion++; } /** * Send queued responses to blkif requests. * * \param xbb Per-instance xbb configuration structure. * \param run_taskqueue Flag that is set to 1 if the taskqueue * should be run, 0 if it does not need to be run. * \param notify Flag that is set to 1 if the other end should be * notified via irq, 0 if the other end should not be * notified. */ static void xbb_push_responses(struct xbb_softc *xbb, int *run_taskqueue, int *notify) { int more_to_do; /* * The mutex is required here. */ mtx_assert(&xbb->lock, MA_OWNED); more_to_do = 0; RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&xbb->rings.common, *notify); if (xbb->rings.common.rsp_prod_pvt == xbb->rings.common.req_cons) { /* * Tail check for pending requests. Allows frontend to avoid * notifications if requests are already in flight (lower * overheads and promotes batching). */ RING_FINAL_CHECK_FOR_REQUESTS(&xbb->rings.common, more_to_do); } else if (RING_HAS_UNCONSUMED_REQUESTS(&xbb->rings.common)) { more_to_do = 1; } xbb->reqs_completed += xbb->reqs_queued_for_completion; xbb->reqs_queued_for_completion = 0; *run_taskqueue = more_to_do; } /** * Complete a request list. * * \param xbb Per-instance xbb configuration structure. * \param reqlist Allocated internal request list structure. */ static void xbb_complete_reqlist(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist) { struct xbb_xen_req *nreq; off_t sectors_sent; int notify, run_taskqueue; sectors_sent = 0; if (reqlist->flags & XBB_REQLIST_MAPPED) xbb_unmap_reqlist(reqlist); mtx_lock(&xbb->lock); /* * All I/O is done, send the response. A lock is not necessary * to protect the request list, because all requests have * completed. Therefore this is the only context accessing this * reqlist right now. However, in order to make sure that no one * else queues responses onto the queue or pushes them to the other * side while we're active, we need to hold the lock across the * calls to xbb_queue_response() and xbb_push_responses(). */ STAILQ_FOREACH(nreq, &reqlist->contig_req_list, links) { off_t cur_sectors_sent; /* Put this response on the ring, but don't push yet */ xbb_queue_response(xbb, nreq, reqlist->status); /* We don't report bytes sent if there is an error. */ if (reqlist->status == BLKIF_RSP_OKAY) cur_sectors_sent = nreq->nr_512b_sectors; else cur_sectors_sent = 0; sectors_sent += cur_sectors_sent; devstat_end_transaction(xbb->xbb_stats_in, /*bytes*/cur_sectors_sent << 9, reqlist->ds_tag_type, reqlist->ds_trans_type, /*now*/NULL, /*then*/&nreq->ds_t0); } /* * Take out any sectors not sent. If we wind up negative (which * might happen if an error is reported as well as a residual), just * report 0 sectors sent. */ sectors_sent -= reqlist->residual_512b_sectors; if (sectors_sent < 0) sectors_sent = 0; devstat_end_transaction(xbb->xbb_stats, /*bytes*/ sectors_sent << 9, reqlist->ds_tag_type, reqlist->ds_trans_type, /*now*/NULL, /*then*/&reqlist->ds_t0); xbb_release_reqlist(xbb, reqlist, /*wakeup*/ 1); xbb_push_responses(xbb, &run_taskqueue, ¬ify); mtx_unlock(&xbb->lock); if (run_taskqueue) taskqueue_enqueue(xbb->io_taskqueue, &xbb->io_task); if (notify) xen_intr_signal(xbb->xen_intr_handle); } /** * Completion handler for buffer I/O requests issued by the device * backend driver. * * \param bio The buffer I/O request on which to perform completion * processing. */ static void xbb_bio_done(struct bio *bio) { struct xbb_softc *xbb; struct xbb_xen_reqlist *reqlist; reqlist = bio->bio_caller1; xbb = reqlist->xbb; reqlist->residual_512b_sectors += bio->bio_resid >> 9; /* * This is a bit imprecise. With aggregated I/O a single * request list can contain multiple front-end requests and * a multiple bios may point to a single request. By carefully * walking the request list, we could map residuals and errors * back to the original front-end request, but the interface * isn't sufficiently rich for us to properly report the error. * So, we just treat the entire request list as having failed if an * error occurs on any part. And, if an error occurs, we treat * the amount of data transferred as 0. * * For residuals, we report it on the overall aggregated device, * but not on the individual requests, since we don't currently * do the work to determine which front-end request to which the * residual applies. */ if (bio->bio_error) { DPRINTF("BIO returned error %d for operation on device %s\n", bio->bio_error, xbb->dev_name); reqlist->status = BLKIF_RSP_ERROR; if (bio->bio_error == ENXIO && xenbus_get_state(xbb->dev) == XenbusStateConnected) { /* * Backend device has disappeared. Signal the * front-end that we (the device proxy) want to * go away. */ xenbus_set_state(xbb->dev, XenbusStateClosing); } } #ifdef XBB_USE_BOUNCE_BUFFERS if (bio->bio_cmd == BIO_READ) { vm_offset_t kva_offset; kva_offset = (vm_offset_t)bio->bio_data - (vm_offset_t)reqlist->bounce; memcpy((uint8_t *)reqlist->kva + kva_offset, bio->bio_data, bio->bio_bcount); } #endif /* XBB_USE_BOUNCE_BUFFERS */ /* * Decrement the pending count for the request list. When we're * done with the requests, send status back for all of them. */ if (atomic_fetchadd_int(&reqlist->pendcnt, -1) == 1) xbb_complete_reqlist(xbb, reqlist); g_destroy_bio(bio); } /** * Parse a blkif request into an internal request structure and send * it to the backend for processing. * * \param xbb Per-instance xbb configuration structure. * \param reqlist Allocated internal request list structure. * * \return On success, 0. For resource shortages, non-zero. * * This routine performs the backend common aspects of request parsing * including compiling an internal request structure, parsing the S/G * list and any secondary ring requests in which they may reside, and * the mapping of front-end I/O pages into our domain. */ static int xbb_dispatch_io(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist) { struct xbb_sg *xbb_sg; struct gnttab_map_grant_ref *map; struct blkif_request_segment *sg; struct blkif_request_segment *last_block_sg; struct xbb_xen_req *nreq; u_int nseg; u_int seg_idx; u_int block_segs; int nr_sects; int total_sects; int operation; uint8_t bio_flags; int error; reqlist->ds_tag_type = DEVSTAT_TAG_SIMPLE; bio_flags = 0; total_sects = 0; nr_sects = 0; /* * First determine whether we have enough free KVA to satisfy this * request list. If not, tell xbb_run_queue() so it can go to * sleep until we have more KVA. */ reqlist->kva = NULL; if (reqlist->nr_segments != 0) { reqlist->kva = xbb_get_kva(xbb, reqlist->nr_segments); if (reqlist->kva == NULL) { /* * If we're out of KVA, return ENOMEM. */ return (ENOMEM); } } binuptime(&reqlist->ds_t0); devstat_start_transaction(xbb->xbb_stats, &reqlist->ds_t0); switch (reqlist->operation) { case BLKIF_OP_WRITE_BARRIER: bio_flags |= BIO_ORDERED; reqlist->ds_tag_type = DEVSTAT_TAG_ORDERED; /* FALLTHROUGH */ case BLKIF_OP_WRITE: operation = BIO_WRITE; reqlist->ds_trans_type = DEVSTAT_WRITE; if ((xbb->flags & XBBF_READ_ONLY) != 0) { DPRINTF("Attempt to write to read only device %s\n", xbb->dev_name); reqlist->status = BLKIF_RSP_ERROR; goto send_response; } break; case BLKIF_OP_READ: operation = BIO_READ; reqlist->ds_trans_type = DEVSTAT_READ; break; case BLKIF_OP_FLUSH_DISKCACHE: /* * If this is true, the user has requested that we disable * flush support. So we just complete the requests * successfully. */ if (xbb->disable_flush != 0) { goto send_response; } /* * The user has requested that we only send a real flush * for every N flush requests. So keep count, and either * complete the request immediately or queue it for the * backend. */ if (xbb->flush_interval != 0) { if (++(xbb->flush_count) < xbb->flush_interval) { goto send_response; } else xbb->flush_count = 0; } operation = BIO_FLUSH; reqlist->ds_tag_type = DEVSTAT_TAG_ORDERED; reqlist->ds_trans_type = DEVSTAT_NO_DATA; goto do_dispatch; /*NOTREACHED*/ default: DPRINTF("error: unknown block io operation [%d]\n", reqlist->operation); reqlist->status = BLKIF_RSP_ERROR; goto send_response; } reqlist->xbb = xbb; xbb_sg = xbb->xbb_sgs; map = xbb->maps; seg_idx = 0; STAILQ_FOREACH(nreq, &reqlist->contig_req_list, links) { blkif_request_t *ring_req; RING_IDX req_ring_idx; u_int req_seg_idx; ring_req = nreq->ring_req; req_ring_idx = nreq->req_ring_idx; nr_sects = 0; nseg = ring_req->nr_segments; nreq->nr_pages = nseg; nreq->nr_512b_sectors = 0; req_seg_idx = 0; sg = NULL; /* Check that number of segments is sane. */ if (__predict_false(nseg == 0) || __predict_false(nseg > xbb->max_request_segments)) { DPRINTF("Bad number of segments in request (%d)\n", nseg); reqlist->status = BLKIF_RSP_ERROR; goto send_response; } block_segs = nseg; sg = ring_req->seg; last_block_sg = sg + block_segs; while (sg < last_block_sg) { KASSERT(seg_idx < XBB_MAX_SEGMENTS_PER_REQLIST, ("seg_idx %d is too large, max " "segs %d\n", seg_idx, XBB_MAX_SEGMENTS_PER_REQLIST)); xbb_sg->first_sect = sg->first_sect; xbb_sg->last_sect = sg->last_sect; xbb_sg->nsect = (int8_t)(sg->last_sect - sg->first_sect + 1); if ((sg->last_sect >= (PAGE_SIZE >> 9)) || (xbb_sg->nsect <= 0)) { reqlist->status = BLKIF_RSP_ERROR; goto send_response; } nr_sects += xbb_sg->nsect; map->host_addr = xbb_get_gntaddr(reqlist, seg_idx, /*sector*/0); KASSERT(map->host_addr + PAGE_SIZE <= xbb->ring_config.gnt_addr, ("Host address %#jx len %d overlaps " "ring address %#jx\n", (uintmax_t)map->host_addr, PAGE_SIZE, (uintmax_t)xbb->ring_config.gnt_addr)); map->flags = GNTMAP_host_map; map->ref = sg->gref; map->dom = xbb->otherend_id; if (operation == BIO_WRITE) map->flags |= GNTMAP_readonly; sg++; map++; xbb_sg++; seg_idx++; req_seg_idx++; } /* Convert to the disk's sector size */ nreq->nr_512b_sectors = nr_sects; nr_sects = (nr_sects << 9) >> xbb->sector_size_shift; total_sects += nr_sects; if ((nreq->nr_512b_sectors & ((xbb->sector_size >> 9) - 1)) != 0) { device_printf(xbb->dev, "%s: I/O size (%d) is not " "a multiple of the backing store sector " "size (%d)\n", __func__, nreq->nr_512b_sectors << 9, xbb->sector_size); reqlist->status = BLKIF_RSP_ERROR; goto send_response; } } error = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, xbb->maps, reqlist->nr_segments); if (error != 0) panic("Grant table operation failed (%d)", error); reqlist->flags |= XBB_REQLIST_MAPPED; for (seg_idx = 0, map = xbb->maps; seg_idx < reqlist->nr_segments; seg_idx++, map++){ if (__predict_false(map->status != 0)) { DPRINTF("invalid buffer -- could not remap " "it (%d)\n", map->status); DPRINTF("Mapping(%d): Host Addr 0x%"PRIx64", flags " "0x%x ref 0x%x, dom %d\n", seg_idx, map->host_addr, map->flags, map->ref, map->dom); reqlist->status = BLKIF_RSP_ERROR; goto send_response; } reqlist->gnt_handles[seg_idx] = map->handle; } if (reqlist->starting_sector_number + total_sects > xbb->media_num_sectors) { DPRINTF("%s of [%" PRIu64 ",%" PRIu64 "] " "extends past end of device %s\n", operation == BIO_READ ? "read" : "write", reqlist->starting_sector_number, reqlist->starting_sector_number + total_sects, xbb->dev_name); reqlist->status = BLKIF_RSP_ERROR; goto send_response; } do_dispatch: error = xbb->dispatch_io(xbb, reqlist, operation, bio_flags); if (error != 0) { reqlist->status = BLKIF_RSP_ERROR; goto send_response; } return (0); send_response: xbb_complete_reqlist(xbb, reqlist); return (0); } static __inline int xbb_count_sects(blkif_request_t *ring_req) { int i; int cur_size = 0; for (i = 0; i < ring_req->nr_segments; i++) { int nsect; nsect = (int8_t)(ring_req->seg[i].last_sect - ring_req->seg[i].first_sect + 1); if (nsect <= 0) break; cur_size += nsect; } return (cur_size); } /** * Process incoming requests from the shared communication ring in response * to a signal on the ring's event channel. * * \param context Callback argument registerd during task initialization - * the xbb_softc for this instance. * \param pending The number of taskqueue_enqueue events that have * occurred since this handler was last run. */ static void xbb_run_queue(void *context, int pending) { struct xbb_softc *xbb; blkif_back_rings_t *rings; RING_IDX rp; uint64_t cur_sector; int cur_operation; struct xbb_xen_reqlist *reqlist; xbb = (struct xbb_softc *)context; rings = &xbb->rings; /* * Work gather and dispatch loop. Note that we have a bias here * towards gathering I/O sent by blockfront. We first gather up * everything in the ring, as long as we have resources. Then we * dispatch one request, and then attempt to gather up any * additional requests that have come in while we were dispatching * the request. * * This allows us to get a clearer picture (via devstat) of how * many requests blockfront is queueing to us at any given time. */ for (;;) { int retval; /* * Initialize reqlist to the last element in the pending * queue, if there is one. This allows us to add more * requests to that request list, if we have room. */ reqlist = STAILQ_LAST(&xbb->reqlist_pending_stailq, xbb_xen_reqlist, links); if (reqlist != NULL) { cur_sector = reqlist->next_contig_sector; cur_operation = reqlist->operation; } else { cur_operation = 0; cur_sector = 0; } /* * Cache req_prod to avoid accessing a cache line shared * with the frontend. */ rp = rings->common.sring->req_prod; /* Ensure we see queued requests up to 'rp'. */ rmb(); /** * Run so long as there is work to consume and the generation * of a response will not overflow the ring. * * @note There's a 1 to 1 relationship between requests and * responses, so an overflow should never occur. This * test is to protect our domain from digesting bogus * data. Shouldn't we log this? */ while (rings->common.req_cons != rp && RING_REQUEST_CONS_OVERFLOW(&rings->common, rings->common.req_cons) == 0){ blkif_request_t ring_req_storage; blkif_request_t *ring_req; int cur_size; switch (xbb->abi) { case BLKIF_PROTOCOL_NATIVE: ring_req = RING_GET_REQUEST(&xbb->rings.native, rings->common.req_cons); break; case BLKIF_PROTOCOL_X86_32: { struct blkif_x86_32_request *ring_req32; ring_req32 = RING_GET_REQUEST( &xbb->rings.x86_32, rings->common.req_cons); blkif_get_x86_32_req(&ring_req_storage, ring_req32); ring_req = &ring_req_storage; break; } case BLKIF_PROTOCOL_X86_64: { struct blkif_x86_64_request *ring_req64; ring_req64 =RING_GET_REQUEST(&xbb->rings.x86_64, rings->common.req_cons); blkif_get_x86_64_req(&ring_req_storage, ring_req64); ring_req = &ring_req_storage; break; } default: panic("Unexpected blkif protocol ABI."); /* NOTREACHED */ } /* * Check for situations that would require closing * off this I/O for further coalescing: * - Coalescing is turned off. * - Current I/O is out of sequence with the previous * I/O. * - Coalesced I/O would be too large. */ if ((reqlist != NULL) && ((xbb->no_coalesce_reqs != 0) || ((xbb->no_coalesce_reqs == 0) && ((ring_req->sector_number != cur_sector) || (ring_req->operation != cur_operation) || ((ring_req->nr_segments + reqlist->nr_segments) > xbb->max_reqlist_segments))))) { reqlist = NULL; } /* * Grab and check for all resources in one shot. * If we can't get all of the resources we need, * the shortage is noted and the thread will get * woken up when more resources are available. */ retval = xbb_get_resources(xbb, &reqlist, ring_req, xbb->rings.common.req_cons); if (retval != 0) { /* * Resource shortage has been recorded. * We'll be scheduled to run once a request * object frees up due to a completion. */ break; } /* * Signify that we can overwrite this request with * a response by incrementing our consumer index. * The response won't be generated until after * we've already consumed all necessary data out * of the version of the request in the ring buffer * (for native mode). We must update the consumer * index before issuing back-end I/O so there is * no possibility that it will complete and a * response be generated before we make room in * the queue for that response. */ xbb->rings.common.req_cons++; xbb->reqs_received++; cur_size = xbb_count_sects(ring_req); cur_sector = ring_req->sector_number + cur_size; reqlist->next_contig_sector = cur_sector; cur_operation = ring_req->operation; } /* Check for I/O to dispatch */ reqlist = STAILQ_FIRST(&xbb->reqlist_pending_stailq); if (reqlist == NULL) { /* * We're out of work to do, put the task queue to * sleep. */ break; } /* * Grab the first request off the queue and attempt * to dispatch it. */ STAILQ_REMOVE_HEAD(&xbb->reqlist_pending_stailq, links); retval = xbb_dispatch_io(xbb, reqlist); if (retval != 0) { /* * xbb_dispatch_io() returns non-zero only when * there is a resource shortage. If that's the * case, re-queue this request on the head of the * queue, and go to sleep until we have more * resources. */ STAILQ_INSERT_HEAD(&xbb->reqlist_pending_stailq, reqlist, links); break; } else { /* * If we still have anything on the queue after * removing the head entry, that is because we * met one of the criteria to create a new * request list (outlined above), and we'll call * that a forced dispatch for statistical purposes. * * Otherwise, if there is only one element on the * queue, we coalesced everything available on * the ring and we'll call that a normal dispatch. */ reqlist = STAILQ_FIRST(&xbb->reqlist_pending_stailq); if (reqlist != NULL) xbb->forced_dispatch++; else xbb->normal_dispatch++; xbb->total_dispatch++; } } } /** * Interrupt handler bound to the shared ring's event channel. * * \param arg Callback argument registerd during event channel * binding - the xbb_softc for this instance. */ static int xbb_filter(void *arg) { struct xbb_softc *xbb; /* Defer to taskqueue thread. */ xbb = (struct xbb_softc *)arg; taskqueue_enqueue(xbb->io_taskqueue, &xbb->io_task); return (FILTER_HANDLED); } SDT_PROVIDER_DEFINE(xbb); SDT_PROBE_DEFINE1(xbb, kernel, xbb_dispatch_dev, flush, "int"); SDT_PROBE_DEFINE3(xbb, kernel, xbb_dispatch_dev, read, "int", "uint64_t", "uint64_t"); SDT_PROBE_DEFINE3(xbb, kernel, xbb_dispatch_dev, write, "int", "uint64_t", "uint64_t"); /*----------------------------- Backend Handlers -----------------------------*/ /** * Backend handler for character device access. * * \param xbb Per-instance xbb configuration structure. * \param reqlist Allocated internal request list structure. * \param operation BIO_* I/O operation code. * \param bio_flags Additional bio_flag data to pass to any generated * bios (e.g. BIO_ORDERED).. * * \return 0 for success, errno codes for failure. */ static int xbb_dispatch_dev(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist, int operation, int bio_flags) { struct xbb_dev_data *dev_data; struct bio *bios[XBB_MAX_SEGMENTS_PER_REQLIST]; off_t bio_offset; struct bio *bio; struct xbb_sg *xbb_sg; u_int nbio; u_int bio_idx; u_int nseg; u_int seg_idx; int error; dev_data = &xbb->backend.dev; bio_offset = (off_t)reqlist->starting_sector_number << xbb->sector_size_shift; error = 0; nbio = 0; bio_idx = 0; if (operation == BIO_FLUSH) { bio = g_new_bio(); if (__predict_false(bio == NULL)) { DPRINTF("Unable to allocate bio for BIO_FLUSH\n"); error = ENOMEM; return (error); } bio->bio_cmd = BIO_FLUSH; bio->bio_flags |= BIO_ORDERED; bio->bio_dev = dev_data->cdev; bio->bio_offset = 0; bio->bio_data = 0; bio->bio_done = xbb_bio_done; bio->bio_caller1 = reqlist; bio->bio_pblkno = 0; reqlist->pendcnt = 1; SDT_PROBE1(xbb, kernel, xbb_dispatch_dev, flush, device_get_unit(xbb->dev)); (*dev_data->csw->d_strategy)(bio); return (0); } xbb_sg = xbb->xbb_sgs; bio = NULL; nseg = reqlist->nr_segments; for (seg_idx = 0; seg_idx < nseg; seg_idx++, xbb_sg++) { /* * KVA will not be contiguous, so any additional * I/O will need to be represented in a new bio. */ if ((bio != NULL) && (xbb_sg->first_sect != 0)) { if ((bio->bio_length & (xbb->sector_size - 1)) != 0) { printf("%s: Discontiguous I/O request " "from domain %d ends on " "non-sector boundary\n", __func__, xbb->otherend_id); error = EINVAL; goto fail_free_bios; } bio = NULL; } if (bio == NULL) { /* * Make sure that the start of this bio is * aligned to a device sector. */ if ((bio_offset & (xbb->sector_size - 1)) != 0){ printf("%s: Misaligned I/O request " "from domain %d\n", __func__, xbb->otherend_id); error = EINVAL; goto fail_free_bios; } bio = bios[nbio++] = g_new_bio(); if (__predict_false(bio == NULL)) { error = ENOMEM; goto fail_free_bios; } bio->bio_cmd = operation; bio->bio_flags |= bio_flags; bio->bio_dev = dev_data->cdev; bio->bio_offset = bio_offset; bio->bio_data = xbb_reqlist_ioaddr(reqlist, seg_idx, xbb_sg->first_sect); bio->bio_done = xbb_bio_done; bio->bio_caller1 = reqlist; bio->bio_pblkno = bio_offset >> xbb->sector_size_shift; } bio->bio_length += xbb_sg->nsect << 9; bio->bio_bcount = bio->bio_length; bio_offset += xbb_sg->nsect << 9; if (xbb_sg->last_sect != (PAGE_SIZE - 512) >> 9) { if ((bio->bio_length & (xbb->sector_size - 1)) != 0) { printf("%s: Discontiguous I/O request " "from domain %d ends on " "non-sector boundary\n", __func__, xbb->otherend_id); error = EINVAL; goto fail_free_bios; } /* * KVA will not be contiguous, so any additional * I/O will need to be represented in a new bio. */ bio = NULL; } } reqlist->pendcnt = nbio; for (bio_idx = 0; bio_idx < nbio; bio_idx++) { #ifdef XBB_USE_BOUNCE_BUFFERS vm_offset_t kva_offset; kva_offset = (vm_offset_t)bios[bio_idx]->bio_data - (vm_offset_t)reqlist->bounce; if (operation == BIO_WRITE) { memcpy(bios[bio_idx]->bio_data, (uint8_t *)reqlist->kva + kva_offset, bios[bio_idx]->bio_bcount); } #endif if (operation == BIO_READ) { SDT_PROBE3(xbb, kernel, xbb_dispatch_dev, read, device_get_unit(xbb->dev), bios[bio_idx]->bio_offset, bios[bio_idx]->bio_length); } else if (operation == BIO_WRITE) { SDT_PROBE3(xbb, kernel, xbb_dispatch_dev, write, device_get_unit(xbb->dev), bios[bio_idx]->bio_offset, bios[bio_idx]->bio_length); } (*dev_data->csw->d_strategy)(bios[bio_idx]); } return (error); fail_free_bios: for (bio_idx = 0; bio_idx < (nbio-1); bio_idx++) g_destroy_bio(bios[bio_idx]); return (error); } SDT_PROBE_DEFINE1(xbb, kernel, xbb_dispatch_file, flush, "int"); SDT_PROBE_DEFINE3(xbb, kernel, xbb_dispatch_file, read, "int", "uint64_t", "uint64_t"); SDT_PROBE_DEFINE3(xbb, kernel, xbb_dispatch_file, write, "int", "uint64_t", "uint64_t"); /** * Backend handler for file access. * * \param xbb Per-instance xbb configuration structure. * \param reqlist Allocated internal request list. * \param operation BIO_* I/O operation code. * \param flags Additional bio_flag data to pass to any generated bios * (e.g. BIO_ORDERED).. * * \return 0 for success, errno codes for failure. */ static int xbb_dispatch_file(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist, int operation, int flags) { struct xbb_file_data *file_data; u_int seg_idx; u_int nseg; struct uio xuio; struct xbb_sg *xbb_sg; struct iovec *xiovec; #ifdef XBB_USE_BOUNCE_BUFFERS void **p_vaddr; int saved_uio_iovcnt; #endif /* XBB_USE_BOUNCE_BUFFERS */ int error; file_data = &xbb->backend.file; error = 0; bzero(&xuio, sizeof(xuio)); switch (operation) { case BIO_READ: xuio.uio_rw = UIO_READ; break; case BIO_WRITE: xuio.uio_rw = UIO_WRITE; break; case BIO_FLUSH: { struct mount *mountpoint; SDT_PROBE1(xbb, kernel, xbb_dispatch_file, flush, device_get_unit(xbb->dev)); (void) vn_start_write(xbb->vn, &mountpoint, V_WAIT); vn_lock(xbb->vn, LK_EXCLUSIVE | LK_RETRY); error = VOP_FSYNC(xbb->vn, MNT_WAIT, curthread); VOP_UNLOCK(xbb->vn); vn_finished_write(mountpoint); goto bailout_send_response; /* NOTREACHED */ } default: panic("invalid operation %d", operation); /* NOTREACHED */ } xuio.uio_offset = (vm_offset_t)reqlist->starting_sector_number << xbb->sector_size_shift; xuio.uio_segflg = UIO_SYSSPACE; xuio.uio_iov = file_data->xiovecs; xuio.uio_iovcnt = 0; xbb_sg = xbb->xbb_sgs; nseg = reqlist->nr_segments; for (xiovec = NULL, seg_idx = 0; seg_idx < nseg; seg_idx++, xbb_sg++) { /* * If the first sector is not 0, the KVA will * not be contiguous and we'll need to go on * to another segment. */ if (xbb_sg->first_sect != 0) xiovec = NULL; if (xiovec == NULL) { xiovec = &file_data->xiovecs[xuio.uio_iovcnt]; xiovec->iov_base = xbb_reqlist_ioaddr(reqlist, seg_idx, xbb_sg->first_sect); #ifdef XBB_USE_BOUNCE_BUFFERS /* * Store the address of the incoming * buffer at this particular offset * as well, so we can do the copy * later without having to do more * work to recalculate this address. */ p_vaddr = &file_data->xiovecs_vaddr[xuio.uio_iovcnt]; *p_vaddr = xbb_reqlist_vaddr(reqlist, seg_idx, xbb_sg->first_sect); #endif /* XBB_USE_BOUNCE_BUFFERS */ xiovec->iov_len = 0; xuio.uio_iovcnt++; } xiovec->iov_len += xbb_sg->nsect << 9; xuio.uio_resid += xbb_sg->nsect << 9; /* * If the last sector is not the full page * size count, the next segment will not be * contiguous in KVA and we need a new iovec. */ if (xbb_sg->last_sect != (PAGE_SIZE - 512) >> 9) xiovec = NULL; } xuio.uio_td = curthread; #ifdef XBB_USE_BOUNCE_BUFFERS saved_uio_iovcnt = xuio.uio_iovcnt; if (operation == BIO_WRITE) { /* Copy the write data to the local buffer. */ for (seg_idx = 0, p_vaddr = file_data->xiovecs_vaddr, xiovec = xuio.uio_iov; seg_idx < xuio.uio_iovcnt; seg_idx++, xiovec++, p_vaddr++) { memcpy(xiovec->iov_base, *p_vaddr, xiovec->iov_len); } } else { /* * We only need to save off the iovecs in the case of a * read, because the copy for the read happens after the * VOP_READ(). (The uio will get modified in that call * sequence.) */ memcpy(file_data->saved_xiovecs, xuio.uio_iov, xuio.uio_iovcnt * sizeof(xuio.uio_iov[0])); } #endif /* XBB_USE_BOUNCE_BUFFERS */ switch (operation) { case BIO_READ: SDT_PROBE3(xbb, kernel, xbb_dispatch_file, read, device_get_unit(xbb->dev), xuio.uio_offset, xuio.uio_resid); vn_lock(xbb->vn, LK_EXCLUSIVE | LK_RETRY); /* * UFS pays attention to IO_DIRECT for reads. If the * DIRECTIO option is configured into the kernel, it calls * ffs_rawread(). But that only works for single-segment * uios with user space addresses. In our case, with a * kernel uio, it still reads into the buffer cache, but it * will just try to release the buffer from the cache later * on in ffs_read(). * * ZFS does not pay attention to IO_DIRECT for reads. * * UFS does not pay attention to IO_SYNC for reads. * * ZFS pays attention to IO_SYNC (which translates into the * Solaris define FRSYNC for zfs_read()) for reads. It * attempts to sync the file before reading. * * So, to attempt to provide some barrier semantics in the * BIO_ORDERED case, set both IO_DIRECT and IO_SYNC. */ error = VOP_READ(xbb->vn, &xuio, (flags & BIO_ORDERED) ? (IO_DIRECT|IO_SYNC) : 0, file_data->cred); VOP_UNLOCK(xbb->vn); break; case BIO_WRITE: { struct mount *mountpoint; SDT_PROBE3(xbb, kernel, xbb_dispatch_file, write, device_get_unit(xbb->dev), xuio.uio_offset, xuio.uio_resid); (void)vn_start_write(xbb->vn, &mountpoint, V_WAIT); vn_lock(xbb->vn, LK_EXCLUSIVE | LK_RETRY); /* * UFS pays attention to IO_DIRECT for writes. The write * is done asynchronously. (Normally the write would just * get put into cache. * * UFS pays attention to IO_SYNC for writes. It will * attempt to write the buffer out synchronously if that * flag is set. * * ZFS does not pay attention to IO_DIRECT for writes. * * ZFS pays attention to IO_SYNC (a.k.a. FSYNC or FRSYNC) * for writes. It will flush the transaction from the * cache before returning. * * So if we've got the BIO_ORDERED flag set, we want * IO_SYNC in either the UFS or ZFS case. */ error = VOP_WRITE(xbb->vn, &xuio, (flags & BIO_ORDERED) ? IO_SYNC : 0, file_data->cred); VOP_UNLOCK(xbb->vn); vn_finished_write(mountpoint); break; } default: panic("invalid operation %d", operation); /* NOTREACHED */ } #ifdef XBB_USE_BOUNCE_BUFFERS /* We only need to copy here for read operations */ if (operation == BIO_READ) { for (seg_idx = 0, p_vaddr = file_data->xiovecs_vaddr, xiovec = file_data->saved_xiovecs; seg_idx < saved_uio_iovcnt; seg_idx++, xiovec++, p_vaddr++) { /* * Note that we have to use the copy of the * io vector we made above. uiomove() modifies * the uio and its referenced vector as uiomove * performs the copy, so we can't rely on any * state from the original uio. */ memcpy(*p_vaddr, xiovec->iov_base, xiovec->iov_len); } } #endif /* XBB_USE_BOUNCE_BUFFERS */ bailout_send_response: if (error != 0) reqlist->status = BLKIF_RSP_ERROR; xbb_complete_reqlist(xbb, reqlist); return (0); } /*--------------------------- Backend Configuration --------------------------*/ /** * Close and cleanup any backend device/file specific state for this * block back instance. * * \param xbb Per-instance xbb configuration structure. */ static void xbb_close_backend(struct xbb_softc *xbb) { DROP_GIANT(); DPRINTF("closing dev=%s\n", xbb->dev_name); if (xbb->vn) { int flags = FREAD; if ((xbb->flags & XBBF_READ_ONLY) == 0) flags |= FWRITE; switch (xbb->device_type) { case XBB_TYPE_DISK: if (xbb->backend.dev.csw) { dev_relthread(xbb->backend.dev.cdev, xbb->backend.dev.dev_ref); xbb->backend.dev.csw = NULL; xbb->backend.dev.cdev = NULL; } break; case XBB_TYPE_FILE: break; case XBB_TYPE_NONE: default: panic("Unexpected backend type."); break; } (void)vn_close(xbb->vn, flags, NOCRED, curthread); xbb->vn = NULL; switch (xbb->device_type) { case XBB_TYPE_DISK: break; case XBB_TYPE_FILE: if (xbb->backend.file.cred != NULL) { crfree(xbb->backend.file.cred); xbb->backend.file.cred = NULL; } break; case XBB_TYPE_NONE: default: panic("Unexpected backend type."); break; } } PICKUP_GIANT(); } /** * Open a character device to be used for backend I/O. * * \param xbb Per-instance xbb configuration structure. * * \return 0 for success, errno codes for failure. */ static int xbb_open_dev(struct xbb_softc *xbb) { struct vattr vattr; struct cdev *dev; struct cdevsw *devsw; int error; xbb->device_type = XBB_TYPE_DISK; xbb->dispatch_io = xbb_dispatch_dev; xbb->backend.dev.cdev = xbb->vn->v_rdev; xbb->backend.dev.csw = dev_refthread(xbb->backend.dev.cdev, &xbb->backend.dev.dev_ref); if (xbb->backend.dev.csw == NULL) panic("Unable to retrieve device switch"); error = VOP_GETATTR(xbb->vn, &vattr, NOCRED); if (error) { xenbus_dev_fatal(xbb->dev, error, "error getting " "vnode attributes for device %s", xbb->dev_name); return (error); } dev = xbb->vn->v_rdev; devsw = dev->si_devsw; if (!devsw->d_ioctl) { xenbus_dev_fatal(xbb->dev, ENODEV, "no d_ioctl for " "device %s!", xbb->dev_name); return (ENODEV); } error = devsw->d_ioctl(dev, DIOCGSECTORSIZE, (caddr_t)&xbb->sector_size, FREAD, curthread); if (error) { xenbus_dev_fatal(xbb->dev, error, "error calling ioctl DIOCGSECTORSIZE " "for device %s", xbb->dev_name); return (error); } error = devsw->d_ioctl(dev, DIOCGMEDIASIZE, (caddr_t)&xbb->media_size, FREAD, curthread); if (error) { xenbus_dev_fatal(xbb->dev, error, "error calling ioctl DIOCGMEDIASIZE " "for device %s", xbb->dev_name); return (error); } return (0); } /** * Open a file to be used for backend I/O. * * \param xbb Per-instance xbb configuration structure. * * \return 0 for success, errno codes for failure. */ static int xbb_open_file(struct xbb_softc *xbb) { struct xbb_file_data *file_data; struct vattr vattr; int error; file_data = &xbb->backend.file; xbb->device_type = XBB_TYPE_FILE; xbb->dispatch_io = xbb_dispatch_file; error = VOP_GETATTR(xbb->vn, &vattr, curthread->td_ucred); if (error != 0) { xenbus_dev_fatal(xbb->dev, error, "error calling VOP_GETATTR()" "for file %s", xbb->dev_name); return (error); } /* * Verify that we have the ability to upgrade to exclusive * access on this file so we can trap errors at open instead * of reporting them during first access. */ if (VOP_ISLOCKED(xbb->vn) != LK_EXCLUSIVE) { vn_lock(xbb->vn, LK_UPGRADE | LK_RETRY); if (VN_IS_DOOMED(xbb->vn)) { error = EBADF; xenbus_dev_fatal(xbb->dev, error, "error locking file %s", xbb->dev_name); return (error); } } file_data->cred = crhold(curthread->td_ucred); xbb->media_size = vattr.va_size; /* * XXX KDM vattr.va_blocksize may be larger than 512 bytes here. * With ZFS, it is 131072 bytes. Block sizes that large don't work * with disklabel and UFS on FreeBSD at least. Large block sizes * may not work with other OSes as well. So just export a sector * size of 512 bytes, which should work with any OS or * application. Since our backing is a file, any block size will * work fine for the backing store. */ #if 0 xbb->sector_size = vattr.va_blocksize; #endif xbb->sector_size = 512; /* * Sanity check. The media size has to be at least one * sector long. */ if (xbb->media_size < xbb->sector_size) { error = EINVAL; xenbus_dev_fatal(xbb->dev, error, "file %s size %ju < block size %u", xbb->dev_name, (uintmax_t)xbb->media_size, xbb->sector_size); } return (error); } /** * Open the backend provider for this connection. * * \param xbb Per-instance xbb configuration structure. * * \return 0 for success, errno codes for failure. */ static int xbb_open_backend(struct xbb_softc *xbb) { struct nameidata nd; int flags; int error; flags = FREAD; error = 0; DPRINTF("opening dev=%s\n", xbb->dev_name); if (rootvnode == NULL) { xenbus_dev_fatal(xbb->dev, ENOENT, "Root file system not mounted"); return (ENOENT); } if ((xbb->flags & XBBF_READ_ONLY) == 0) flags |= FWRITE; pwd_ensure_dirs(); again: NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, xbb->dev_name, curthread); error = vn_open(&nd, &flags, 0, NULL); if (error) { /* * This is the only reasonable guess we can make as far as * path if the user doesn't give us a fully qualified path. * If they want to specify a file, they need to specify the * full path. */ if (xbb->dev_name[0] != '/') { char *dev_path = "/dev/"; char *dev_name; /* Try adding device path at beginning of name */ dev_name = malloc(strlen(xbb->dev_name) + strlen(dev_path) + 1, M_XENBLOCKBACK, M_NOWAIT); if (dev_name) { sprintf(dev_name, "%s%s", dev_path, xbb->dev_name); free(xbb->dev_name, M_XENBLOCKBACK); xbb->dev_name = dev_name; goto again; } } xenbus_dev_fatal(xbb->dev, error, "error opening device %s", xbb->dev_name); return (error); } NDFREE(&nd, NDF_ONLY_PNBUF); xbb->vn = nd.ni_vp; /* We only support disks and files. */ if (vn_isdisk_error(xbb->vn, &error)) { error = xbb_open_dev(xbb); } else if (xbb->vn->v_type == VREG) { error = xbb_open_file(xbb); } else { error = EINVAL; xenbus_dev_fatal(xbb->dev, error, "%s is not a disk " "or file", xbb->dev_name); } VOP_UNLOCK(xbb->vn); if (error != 0) { xbb_close_backend(xbb); return (error); } xbb->sector_size_shift = fls(xbb->sector_size) - 1; xbb->media_num_sectors = xbb->media_size >> xbb->sector_size_shift; DPRINTF("opened %s=%s sector_size=%u media_size=%" PRId64 "\n", (xbb->device_type == XBB_TYPE_DISK) ? "dev" : "file", xbb->dev_name, xbb->sector_size, xbb->media_size); return (0); } /*------------------------ Inter-Domain Communication ------------------------*/ /** * Free dynamically allocated KVA or pseudo-physical address allocations. * * \param xbb Per-instance xbb configuration structure. */ static void xbb_free_communication_mem(struct xbb_softc *xbb) { if (xbb->kva != 0) { if (xbb->pseudo_phys_res != NULL) { xenmem_free(xbb->dev, xbb->pseudo_phys_res_id, xbb->pseudo_phys_res); xbb->pseudo_phys_res = NULL; } } xbb->kva = 0; xbb->gnt_base_addr = 0; if (xbb->kva_free != NULL) { free(xbb->kva_free, M_XENBLOCKBACK); xbb->kva_free = NULL; } } /** * Cleanup all inter-domain communication mechanisms. * * \param xbb Per-instance xbb configuration structure. */ static int xbb_disconnect(struct xbb_softc *xbb) { struct gnttab_unmap_grant_ref ops[XBB_MAX_RING_PAGES]; struct gnttab_unmap_grant_ref *op; u_int ring_idx; int error; DPRINTF("\n"); if ((xbb->flags & XBBF_RING_CONNECTED) == 0) return (0); mtx_unlock(&xbb->lock); xen_intr_unbind(&xbb->xen_intr_handle); taskqueue_drain(xbb->io_taskqueue, &xbb->io_task); mtx_lock(&xbb->lock); /* * No new interrupts can generate work, but we must wait * for all currently active requests to drain. */ if (xbb->active_request_count != 0) return (EAGAIN); for (ring_idx = 0, op = ops; ring_idx < xbb->ring_config.ring_pages; ring_idx++, op++) { op->host_addr = xbb->ring_config.gnt_addr + (ring_idx * PAGE_SIZE); op->dev_bus_addr = xbb->ring_config.bus_addr[ring_idx]; op->handle = xbb->ring_config.handle[ring_idx]; } error = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, ops, xbb->ring_config.ring_pages); if (error != 0) panic("Grant table op failed (%d)", error); xbb_free_communication_mem(xbb); if (xbb->requests != NULL) { free(xbb->requests, M_XENBLOCKBACK); xbb->requests = NULL; } if (xbb->request_lists != NULL) { struct xbb_xen_reqlist *reqlist; int i; /* There is one request list for ever allocated request. */ for (i = 0, reqlist = xbb->request_lists; i < xbb->max_requests; i++, reqlist++){ #ifdef XBB_USE_BOUNCE_BUFFERS if (reqlist->bounce != NULL) { free(reqlist->bounce, M_XENBLOCKBACK); reqlist->bounce = NULL; } #endif if (reqlist->gnt_handles != NULL) { free(reqlist->gnt_handles, M_XENBLOCKBACK); reqlist->gnt_handles = NULL; } } free(xbb->request_lists, M_XENBLOCKBACK); xbb->request_lists = NULL; } xbb->flags &= ~XBBF_RING_CONNECTED; return (0); } /** * Map shared memory ring into domain local address space, initialize * ring control structures, and bind an interrupt to the event channel * used to notify us of ring changes. * * \param xbb Per-instance xbb configuration structure. */ static int xbb_connect_ring(struct xbb_softc *xbb) { struct gnttab_map_grant_ref gnts[XBB_MAX_RING_PAGES]; struct gnttab_map_grant_ref *gnt; u_int ring_idx; int error; if ((xbb->flags & XBBF_RING_CONNECTED) != 0) return (0); /* * Kva for our ring is at the tail of the region of kva allocated * by xbb_alloc_communication_mem(). */ xbb->ring_config.va = xbb->kva + (xbb->kva_size - (xbb->ring_config.ring_pages * PAGE_SIZE)); xbb->ring_config.gnt_addr = xbb->gnt_base_addr + (xbb->kva_size - (xbb->ring_config.ring_pages * PAGE_SIZE)); for (ring_idx = 0, gnt = gnts; ring_idx < xbb->ring_config.ring_pages; ring_idx++, gnt++) { gnt->host_addr = xbb->ring_config.gnt_addr + (ring_idx * PAGE_SIZE); gnt->flags = GNTMAP_host_map; gnt->ref = xbb->ring_config.ring_ref[ring_idx]; gnt->dom = xbb->otherend_id; } error = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, gnts, xbb->ring_config.ring_pages); if (error) panic("blkback: Ring page grant table op failed (%d)", error); for (ring_idx = 0, gnt = gnts; ring_idx < xbb->ring_config.ring_pages; ring_idx++, gnt++) { if (gnt->status != 0) { xbb->ring_config.va = 0; xenbus_dev_fatal(xbb->dev, EACCES, "Ring shared page mapping failed. " "Status %d.", gnt->status); return (EACCES); } xbb->ring_config.handle[ring_idx] = gnt->handle; xbb->ring_config.bus_addr[ring_idx] = gnt->dev_bus_addr; } /* Initialize the ring based on ABI. */ switch (xbb->abi) { case BLKIF_PROTOCOL_NATIVE: { blkif_sring_t *sring; sring = (blkif_sring_t *)xbb->ring_config.va; BACK_RING_INIT(&xbb->rings.native, sring, xbb->ring_config.ring_pages * PAGE_SIZE); break; } case BLKIF_PROTOCOL_X86_32: { blkif_x86_32_sring_t *sring_x86_32; sring_x86_32 = (blkif_x86_32_sring_t *)xbb->ring_config.va; BACK_RING_INIT(&xbb->rings.x86_32, sring_x86_32, xbb->ring_config.ring_pages * PAGE_SIZE); break; } case BLKIF_PROTOCOL_X86_64: { blkif_x86_64_sring_t *sring_x86_64; sring_x86_64 = (blkif_x86_64_sring_t *)xbb->ring_config.va; BACK_RING_INIT(&xbb->rings.x86_64, sring_x86_64, xbb->ring_config.ring_pages * PAGE_SIZE); break; } default: panic("Unexpected blkif protocol ABI."); } xbb->flags |= XBBF_RING_CONNECTED; error = xen_intr_bind_remote_port(xbb->dev, xbb->otherend_id, xbb->ring_config.evtchn, xbb_filter, /*ithread_handler*/NULL, /*arg*/xbb, INTR_TYPE_BIO | INTR_MPSAFE, &xbb->xen_intr_handle); if (error) { (void)xbb_disconnect(xbb); xenbus_dev_fatal(xbb->dev, error, "binding event channel"); return (error); } DPRINTF("rings connected!\n"); return 0; } /** * Size KVA and pseudo-physical address allocations based on negotiated * values for the size and number of I/O requests, and the size of our * communication ring. * * \param xbb Per-instance xbb configuration structure. * * These address spaces are used to dynamically map pages in the * front-end's domain into our own. */ static int xbb_alloc_communication_mem(struct xbb_softc *xbb) { xbb->reqlist_kva_pages = xbb->max_requests * xbb->max_request_segments; xbb->reqlist_kva_size = xbb->reqlist_kva_pages * PAGE_SIZE; xbb->kva_size = xbb->reqlist_kva_size + (xbb->ring_config.ring_pages * PAGE_SIZE); xbb->kva_free = bit_alloc(xbb->reqlist_kva_pages, M_XENBLOCKBACK, M_NOWAIT); if (xbb->kva_free == NULL) return (ENOMEM); DPRINTF("%s: kva_size = %d, reqlist_kva_size = %d\n", device_get_nameunit(xbb->dev), xbb->kva_size, xbb->reqlist_kva_size); /* * Reserve a range of pseudo physical memory that we can map * into kva. These pages will only be backed by machine * pages ("real memory") during the lifetime of front-end requests * via grant table operations. */ xbb->pseudo_phys_res_id = 0; xbb->pseudo_phys_res = xenmem_alloc(xbb->dev, &xbb->pseudo_phys_res_id, xbb->kva_size); if (xbb->pseudo_phys_res == NULL) { xbb->kva = 0; return (ENOMEM); } xbb->kva = (vm_offset_t)rman_get_virtual(xbb->pseudo_phys_res); xbb->gnt_base_addr = rman_get_start(xbb->pseudo_phys_res); DPRINTF("%s: kva: %#jx, gnt_base_addr: %#jx\n", device_get_nameunit(xbb->dev), (uintmax_t)xbb->kva, (uintmax_t)xbb->gnt_base_addr); return (0); } /** * Collect front-end information from the XenStore. * * \param xbb Per-instance xbb configuration structure. */ static int xbb_collect_frontend_info(struct xbb_softc *xbb) { char protocol_abi[64]; const char *otherend_path; int error; u_int ring_idx; u_int ring_page_order; size_t ring_size; otherend_path = xenbus_get_otherend_path(xbb->dev); /* * Protocol defaults valid even if all negotiation fails. */ xbb->ring_config.ring_pages = 1; xbb->max_request_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; xbb->max_request_size = xbb->max_request_segments * PAGE_SIZE; /* * Mandatory data (used in all versions of the protocol) first. */ error = xs_scanf(XST_NIL, otherend_path, "event-channel", NULL, "%" PRIu32, &xbb->ring_config.evtchn); if (error != 0) { xenbus_dev_fatal(xbb->dev, error, "Unable to retrieve event-channel information " "from frontend %s. Unable to connect.", xenbus_get_otherend_path(xbb->dev)); return (error); } /* * These fields are initialized to legacy protocol defaults * so we only need to fail if reading the updated value succeeds * and the new value is outside of its allowed range. * * \note xs_gather() returns on the first encountered error, so * we must use independent calls in order to guarantee * we don't miss information in a sparsly populated front-end * tree. * * \note xs_scanf() does not update variables for unmatched * fields. */ ring_page_order = 0; xbb->max_requests = 32; (void)xs_scanf(XST_NIL, otherend_path, "ring-page-order", NULL, "%u", &ring_page_order); xbb->ring_config.ring_pages = 1 << ring_page_order; ring_size = PAGE_SIZE * xbb->ring_config.ring_pages; xbb->max_requests = BLKIF_MAX_RING_REQUESTS(ring_size); if (xbb->ring_config.ring_pages > XBB_MAX_RING_PAGES) { xenbus_dev_fatal(xbb->dev, EINVAL, "Front-end specified ring-pages of %u " "exceeds backend limit of %u. " "Unable to connect.", xbb->ring_config.ring_pages, XBB_MAX_RING_PAGES); return (EINVAL); } if (xbb->ring_config.ring_pages == 1) { error = xs_gather(XST_NIL, otherend_path, "ring-ref", "%" PRIu32, &xbb->ring_config.ring_ref[0], NULL); if (error != 0) { xenbus_dev_fatal(xbb->dev, error, "Unable to retrieve ring information " "from frontend %s. Unable to " "connect.", xenbus_get_otherend_path(xbb->dev)); return (error); } } else { /* Multi-page ring format. */ for (ring_idx = 0; ring_idx < xbb->ring_config.ring_pages; ring_idx++) { char ring_ref_name[]= "ring_refXX"; snprintf(ring_ref_name, sizeof(ring_ref_name), "ring-ref%u", ring_idx); error = xs_scanf(XST_NIL, otherend_path, ring_ref_name, NULL, "%" PRIu32, &xbb->ring_config.ring_ref[ring_idx]); if (error != 0) { xenbus_dev_fatal(xbb->dev, error, "Failed to retriev grant " "reference for page %u of " "shared ring. Unable " "to connect.", ring_idx); return (error); } } } error = xs_gather(XST_NIL, otherend_path, "protocol", "%63s", protocol_abi, NULL); if (error != 0 || !strcmp(protocol_abi, XEN_IO_PROTO_ABI_NATIVE)) { /* * Assume native if the frontend has not * published ABI data or it has published and * matches our own ABI. */ xbb->abi = BLKIF_PROTOCOL_NATIVE; } else if (!strcmp(protocol_abi, XEN_IO_PROTO_ABI_X86_32)) { xbb->abi = BLKIF_PROTOCOL_X86_32; } else if (!strcmp(protocol_abi, XEN_IO_PROTO_ABI_X86_64)) { xbb->abi = BLKIF_PROTOCOL_X86_64; } else { xenbus_dev_fatal(xbb->dev, EINVAL, "Unknown protocol ABI (%s) published by " "frontend. Unable to connect.", protocol_abi); return (EINVAL); } return (0); } /** * Allocate per-request data structures given request size and number * information negotiated with the front-end. * * \param xbb Per-instance xbb configuration structure. */ static int xbb_alloc_requests(struct xbb_softc *xbb) { struct xbb_xen_req *req; struct xbb_xen_req *last_req; /* * Allocate request book keeping datastructures. */ xbb->requests = malloc(xbb->max_requests * sizeof(*xbb->requests), M_XENBLOCKBACK, M_NOWAIT|M_ZERO); if (xbb->requests == NULL) { xenbus_dev_fatal(xbb->dev, ENOMEM, "Unable to allocate request structures"); return (ENOMEM); } req = xbb->requests; last_req = &xbb->requests[xbb->max_requests - 1]; STAILQ_INIT(&xbb->request_free_stailq); while (req <= last_req) { STAILQ_INSERT_TAIL(&xbb->request_free_stailq, req, links); req++; } return (0); } static int xbb_alloc_request_lists(struct xbb_softc *xbb) { struct xbb_xen_reqlist *reqlist; int i; /* * If no requests can be merged, we need 1 request list per * in flight request. */ xbb->request_lists = malloc(xbb->max_requests * sizeof(*xbb->request_lists), M_XENBLOCKBACK, M_NOWAIT|M_ZERO); if (xbb->request_lists == NULL) { xenbus_dev_fatal(xbb->dev, ENOMEM, "Unable to allocate request list structures"); return (ENOMEM); } STAILQ_INIT(&xbb->reqlist_free_stailq); STAILQ_INIT(&xbb->reqlist_pending_stailq); for (i = 0; i < xbb->max_requests; i++) { int seg; reqlist = &xbb->request_lists[i]; reqlist->xbb = xbb; #ifdef XBB_USE_BOUNCE_BUFFERS reqlist->bounce = malloc(xbb->max_reqlist_size, M_XENBLOCKBACK, M_NOWAIT); if (reqlist->bounce == NULL) { xenbus_dev_fatal(xbb->dev, ENOMEM, "Unable to allocate request " "bounce buffers"); return (ENOMEM); } #endif /* XBB_USE_BOUNCE_BUFFERS */ reqlist->gnt_handles = malloc(xbb->max_reqlist_segments * sizeof(*reqlist->gnt_handles), M_XENBLOCKBACK, M_NOWAIT|M_ZERO); if (reqlist->gnt_handles == NULL) { xenbus_dev_fatal(xbb->dev, ENOMEM, "Unable to allocate request " "grant references"); return (ENOMEM); } for (seg = 0; seg < xbb->max_reqlist_segments; seg++) reqlist->gnt_handles[seg] = GRANT_REF_INVALID; STAILQ_INSERT_TAIL(&xbb->reqlist_free_stailq, reqlist, links); } return (0); } /** * Supply information about the physical device to the frontend * via XenBus. * * \param xbb Per-instance xbb configuration structure. */ static int xbb_publish_backend_info(struct xbb_softc *xbb) { struct xs_transaction xst; const char *our_path; const char *leaf; int error; our_path = xenbus_get_node(xbb->dev); while (1) { error = xs_transaction_start(&xst); if (error != 0) { xenbus_dev_fatal(xbb->dev, error, "Error publishing backend info " "(start transaction)"); return (error); } leaf = "sectors"; error = xs_printf(xst, our_path, leaf, "%"PRIu64, xbb->media_num_sectors); if (error != 0) break; /* XXX Support all VBD attributes here. */ leaf = "info"; error = xs_printf(xst, our_path, leaf, "%u", xbb->flags & XBBF_READ_ONLY ? VDISK_READONLY : 0); if (error != 0) break; leaf = "sector-size"; error = xs_printf(xst, our_path, leaf, "%u", xbb->sector_size); if (error != 0) break; error = xs_transaction_end(xst, 0); if (error == 0) { return (0); } else if (error != EAGAIN) { xenbus_dev_fatal(xbb->dev, error, "ending transaction"); return (error); } } xenbus_dev_fatal(xbb->dev, error, "writing %s/%s", our_path, leaf); xs_transaction_end(xst, 1); return (error); } /** * Connect to our blkfront peer now that it has completed publishing * its configuration into the XenStore. * * \param xbb Per-instance xbb configuration structure. */ static void xbb_connect(struct xbb_softc *xbb) { int error; if (!xbb->hotplug_done || (xenbus_get_state(xbb->dev) != XenbusStateInitWait) || (xbb_collect_frontend_info(xbb) != 0)) return; xbb->flags &= ~XBBF_SHUTDOWN; /* * We limit the maximum number of reqlist segments to the maximum * number of segments in the ring, or our absolute maximum, * whichever is smaller. */ xbb->max_reqlist_segments = MIN(xbb->max_request_segments * xbb->max_requests, XBB_MAX_SEGMENTS_PER_REQLIST); /* * The maximum size is simply a function of the number of segments * we can handle. */ xbb->max_reqlist_size = xbb->max_reqlist_segments * PAGE_SIZE; /* Allocate resources whose size depends on front-end configuration. */ error = xbb_alloc_communication_mem(xbb); if (error != 0) { xenbus_dev_fatal(xbb->dev, error, "Unable to allocate communication memory"); return; } error = xbb_alloc_requests(xbb); if (error != 0) { /* Specific errors are reported by xbb_alloc_requests(). */ return; } error = xbb_alloc_request_lists(xbb); if (error != 0) { /* Specific errors are reported by xbb_alloc_request_lists(). */ return; } /* * Connect communication channel. */ error = xbb_connect_ring(xbb); if (error != 0) { /* Specific errors are reported by xbb_connect_ring(). */ return; } if (xbb_publish_backend_info(xbb) != 0) { /* * If we can't publish our data, we cannot participate * in this connection, and waiting for a front-end state * change will not help the situation. */ (void)xbb_disconnect(xbb); return; } /* Ready for I/O. */ xenbus_set_state(xbb->dev, XenbusStateConnected); } /*-------------------------- Device Teardown Support -------------------------*/ /** * Perform device shutdown functions. * * \param xbb Per-instance xbb configuration structure. * * Mark this instance as shutting down, wait for any active I/O on the * backend device/file to drain, disconnect from the front-end, and notify * any waiters (e.g. a thread invoking our detach method) that detach can * now proceed. */ static int xbb_shutdown(struct xbb_softc *xbb) { XenbusState frontState; int error; DPRINTF("\n"); /* * Due to the need to drop our mutex during some * xenbus operations, it is possible for two threads * to attempt to close out shutdown processing at * the same time. Tell the caller that hits this * race to try back later. */ if ((xbb->flags & XBBF_IN_SHUTDOWN) != 0) return (EAGAIN); xbb->flags |= XBBF_IN_SHUTDOWN; mtx_unlock(&xbb->lock); if (xbb->hotplug_watch.node != NULL) { xs_unregister_watch(&xbb->hotplug_watch); free(xbb->hotplug_watch.node, M_XENBLOCKBACK); xbb->hotplug_watch.node = NULL; } xbb->hotplug_done = false; if (xenbus_get_state(xbb->dev) < XenbusStateClosing) xenbus_set_state(xbb->dev, XenbusStateClosing); frontState = xenbus_get_otherend_state(xbb->dev); mtx_lock(&xbb->lock); xbb->flags &= ~XBBF_IN_SHUTDOWN; /* Wait for the frontend to disconnect (if it's connected). */ if (frontState == XenbusStateConnected) return (EAGAIN); DPRINTF("\n"); /* Indicate shutdown is in progress. */ xbb->flags |= XBBF_SHUTDOWN; /* Disconnect from the front-end. */ error = xbb_disconnect(xbb); if (error != 0) { /* * Requests still outstanding. We'll be called again * once they complete. */ KASSERT(error == EAGAIN, ("%s: Unexpected xbb_disconnect() failure %d", __func__, error)); return (error); } DPRINTF("\n"); /* Indicate to xbb_detach() that is it safe to proceed. */ wakeup(xbb); return (0); } /** * Report an attach time error to the console and Xen, and cleanup * this instance by forcing immediate detach processing. * * \param xbb Per-instance xbb configuration structure. * \param err Errno describing the error. * \param fmt Printf style format and arguments */ static void xbb_attach_failed(struct xbb_softc *xbb, int err, const char *fmt, ...) { va_list ap; va_list ap_hotplug; va_start(ap, fmt); va_copy(ap_hotplug, ap); xs_vprintf(XST_NIL, xenbus_get_node(xbb->dev), "hotplug-error", fmt, ap_hotplug); va_end(ap_hotplug); xs_printf(XST_NIL, xenbus_get_node(xbb->dev), "hotplug-status", "error"); xenbus_dev_vfatal(xbb->dev, err, fmt, ap); va_end(ap); xs_printf(XST_NIL, xenbus_get_node(xbb->dev), "online", "0"); mtx_lock(&xbb->lock); xbb_shutdown(xbb); mtx_unlock(&xbb->lock); } /*---------------------------- NewBus Entrypoints ----------------------------*/ /** * Inspect a XenBus device and claim it if is of the appropriate type. * * \param dev NewBus device object representing a candidate XenBus device. * * \return 0 for success, errno codes for failure. */ static int xbb_probe(device_t dev) { if (!strcmp(xenbus_get_type(dev), "vbd")) { device_set_desc(dev, "Backend Virtual Block Device"); device_quiet(dev); return (0); } return (ENXIO); } /** * Setup sysctl variables to control various Block Back parameters. * * \param xbb Xen Block Back softc. * */ static void xbb_setup_sysctl(struct xbb_softc *xbb) { struct sysctl_ctx_list *sysctl_ctx = NULL; struct sysctl_oid *sysctl_tree = NULL; sysctl_ctx = device_get_sysctl_ctx(xbb->dev); if (sysctl_ctx == NULL) return; sysctl_tree = device_get_sysctl_tree(xbb->dev); if (sysctl_tree == NULL) return; SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "disable_flush", CTLFLAG_RW, &xbb->disable_flush, 0, "fake the flush command"); SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "flush_interval", CTLFLAG_RW, &xbb->flush_interval, 0, "send a real flush for N flush requests"); SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "no_coalesce_reqs", CTLFLAG_RW, &xbb->no_coalesce_reqs,0, "Don't coalesce contiguous requests"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "reqs_received", CTLFLAG_RW, &xbb->reqs_received, "how many I/O requests we have received"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "reqs_completed", CTLFLAG_RW, &xbb->reqs_completed, "how many I/O requests have been completed"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "reqs_queued_for_completion", CTLFLAG_RW, &xbb->reqs_queued_for_completion, "how many I/O requests queued but not yet pushed"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "reqs_completed_with_error", CTLFLAG_RW, &xbb->reqs_completed_with_error, "how many I/O requests completed with error status"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "forced_dispatch", CTLFLAG_RW, &xbb->forced_dispatch, "how many I/O dispatches were forced"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "normal_dispatch", CTLFLAG_RW, &xbb->normal_dispatch, "how many I/O dispatches were normal"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "total_dispatch", CTLFLAG_RW, &xbb->total_dispatch, "total number of I/O dispatches"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "kva_shortages", CTLFLAG_RW, &xbb->kva_shortages, "how many times we have run out of KVA"); SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "request_shortages", CTLFLAG_RW, &xbb->request_shortages, "how many times we have run out of requests"); SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "max_requests", CTLFLAG_RD, &xbb->max_requests, 0, "maximum outstanding requests (negotiated)"); SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "max_request_segments", CTLFLAG_RD, &xbb->max_request_segments, 0, "maximum number of pages per requests (negotiated)"); SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "max_request_size", CTLFLAG_RD, &xbb->max_request_size, 0, "maximum size in bytes of a request (negotiated)"); SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, "ring_pages", CTLFLAG_RD, &xbb->ring_config.ring_pages, 0, "communication channel pages (negotiated)"); } static void xbb_attach_disk(struct xs_watch *watch, const char **vec, unsigned int len) { device_t dev; struct xbb_softc *xbb; int error; dev = (device_t) watch->callback_data; xbb = device_get_softc(dev); error = xs_gather(XST_NIL, xenbus_get_node(dev), "physical-device-path", NULL, &xbb->dev_name, NULL); if (error != 0) return; xs_unregister_watch(watch); free(watch->node, M_XENBLOCKBACK); watch->node = NULL; /* Collect physical device information. */ error = xs_gather(XST_NIL, xenbus_get_otherend_path(xbb->dev), "device-type", NULL, &xbb->dev_type, NULL); if (error != 0) xbb->dev_type = NULL; error = xs_gather(XST_NIL, xenbus_get_node(dev), "mode", NULL, &xbb->dev_mode, NULL); if (error != 0) { xbb_attach_failed(xbb, error, "reading backend fields at %s", xenbus_get_node(dev)); return; } /* Parse fopen style mode flags. */ if (strchr(xbb->dev_mode, 'w') == NULL) xbb->flags |= XBBF_READ_ONLY; /* * Verify the physical device is present and can support * the desired I/O mode. */ error = xbb_open_backend(xbb); if (error != 0) { xbb_attach_failed(xbb, error, "Unable to open %s", xbb->dev_name); return; } /* Use devstat(9) for recording statistics. */ xbb->xbb_stats = devstat_new_entry("xbb", device_get_unit(xbb->dev), xbb->sector_size, DEVSTAT_ALL_SUPPORTED, DEVSTAT_TYPE_DIRECT | DEVSTAT_TYPE_IF_OTHER, DEVSTAT_PRIORITY_OTHER); xbb->xbb_stats_in = devstat_new_entry("xbbi", device_get_unit(xbb->dev), xbb->sector_size, DEVSTAT_ALL_SUPPORTED, DEVSTAT_TYPE_DIRECT | DEVSTAT_TYPE_IF_OTHER, DEVSTAT_PRIORITY_OTHER); /* * Setup sysctl variables. */ xbb_setup_sysctl(xbb); /* * Create a taskqueue for doing work that must occur from a * thread context. */ xbb->io_taskqueue = taskqueue_create_fast(device_get_nameunit(dev), M_NOWAIT, taskqueue_thread_enqueue, /*contxt*/&xbb->io_taskqueue); if (xbb->io_taskqueue == NULL) { xbb_attach_failed(xbb, error, "Unable to create taskqueue"); return; } taskqueue_start_threads(&xbb->io_taskqueue, /*num threads*/1, /*priority*/PWAIT, /*thread name*/ "%s taskq", device_get_nameunit(dev)); /* Update hot-plug status to satisfy xend. */ error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), "hotplug-status", "connected"); if (error) { xbb_attach_failed(xbb, error, "writing %s/hotplug-status", xenbus_get_node(xbb->dev)); return; } xbb->hotplug_done = true; /* The front end might be waiting for the backend, attach if so. */ if (xenbus_get_otherend_state(xbb->dev) == XenbusStateInitialised) xbb_connect(xbb); } /** * Attach to a XenBus device that has been claimed by our probe routine. * * \param dev NewBus device object representing this Xen Block Back instance. * * \return 0 for success, errno codes for failure. */ static int xbb_attach(device_t dev) { struct xbb_softc *xbb; int error; u_int max_ring_page_order; struct sbuf *watch_path; DPRINTF("Attaching to %s\n", xenbus_get_node(dev)); /* * Basic initialization. * After this block it is safe to call xbb_detach() * to clean up any allocated data for this instance. */ xbb = device_get_softc(dev); xbb->dev = dev; xbb->otherend_id = xenbus_get_otherend_id(dev); TASK_INIT(&xbb->io_task, /*priority*/0, xbb_run_queue, xbb); mtx_init(&xbb->lock, device_get_nameunit(dev), NULL, MTX_DEF); /* * Publish protocol capabilities for consumption by the * front-end. */ error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), "feature-barrier", "1"); if (error) { xbb_attach_failed(xbb, error, "writing %s/feature-barrier", xenbus_get_node(xbb->dev)); return (error); } error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), "feature-flush-cache", "1"); if (error) { xbb_attach_failed(xbb, error, "writing %s/feature-flush-cache", xenbus_get_node(xbb->dev)); return (error); } max_ring_page_order = flsl(XBB_MAX_RING_PAGES) - 1; error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev), "max-ring-page-order", "%u", max_ring_page_order); if (error) { xbb_attach_failed(xbb, error, "writing %s/max-ring-page-order", xenbus_get_node(xbb->dev)); return (error); } /* * We need to wait for hotplug script execution before * moving forward. */ KASSERT(!xbb->hotplug_done, ("Hotplug scripts already executed")); watch_path = xs_join(xenbus_get_node(xbb->dev), "physical-device-path"); xbb->hotplug_watch.callback_data = (uintptr_t)dev; xbb->hotplug_watch.callback = xbb_attach_disk; KASSERT(xbb->hotplug_watch.node == NULL, ("watch node already setup")); xbb->hotplug_watch.node = strdup(sbuf_data(watch_path), M_XENBLOCKBACK); sbuf_delete(watch_path); error = xs_register_watch(&xbb->hotplug_watch); if (error != 0) { xbb_attach_failed(xbb, error, "failed to create watch on %s", xbb->hotplug_watch.node); free(xbb->hotplug_watch.node, M_XENBLOCKBACK); return (error); } /* Tell the toolstack blkback has attached. */ xenbus_set_state(dev, XenbusStateInitWait); return (0); } /** * Detach from a block back device instance. * * \param dev NewBus device object representing this Xen Block Back instance. * * \return 0 for success, errno codes for failure. * * \note A block back device may be detached at any time in its life-cycle, * including part way through the attach process. For this reason, * initialization order and the initialization state checks in this * routine must be carefully coupled so that attach time failures * are gracefully handled. */ static int xbb_detach(device_t dev) { struct xbb_softc *xbb; DPRINTF("\n"); xbb = device_get_softc(dev); mtx_lock(&xbb->lock); while (xbb_shutdown(xbb) == EAGAIN) { msleep(xbb, &xbb->lock, /*wakeup prio unchanged*/0, "xbb_shutdown", 0); } mtx_unlock(&xbb->lock); DPRINTF("\n"); if (xbb->io_taskqueue != NULL) taskqueue_free(xbb->io_taskqueue); if (xbb->xbb_stats != NULL) devstat_remove_entry(xbb->xbb_stats); if (xbb->xbb_stats_in != NULL) devstat_remove_entry(xbb->xbb_stats_in); xbb_close_backend(xbb); if (xbb->dev_mode != NULL) { free(xbb->dev_mode, M_XENSTORE); xbb->dev_mode = NULL; } if (xbb->dev_type != NULL) { free(xbb->dev_type, M_XENSTORE); xbb->dev_type = NULL; } if (xbb->dev_name != NULL) { free(xbb->dev_name, M_XENSTORE); xbb->dev_name = NULL; } mtx_destroy(&xbb->lock); return (0); } /** * Prepare this block back device for suspension of this VM. * * \param dev NewBus device object representing this Xen Block Back instance. * * \return 0 for success, errno codes for failure. */ static int xbb_suspend(device_t dev) { #ifdef NOT_YET struct xbb_softc *sc = device_get_softc(dev); /* Prevent new requests being issued until we fix things up. */ mtx_lock(&sc->xb_io_lock); sc->connected = BLKIF_STATE_SUSPENDED; mtx_unlock(&sc->xb_io_lock); #endif return (0); } /** * Perform any processing required to recover from a suspended state. * * \param dev NewBus device object representing this Xen Block Back instance. * * \return 0 for success, errno codes for failure. */ static int xbb_resume(device_t dev) { return (0); } /** * Handle state changes expressed via the XenStore by our front-end peer. * * \param dev NewBus device object representing this Xen * Block Back instance. * \param frontend_state The new state of the front-end. * * \return 0 for success, errno codes for failure. */ static void xbb_frontend_changed(device_t dev, XenbusState frontend_state) { struct xbb_softc *xbb = device_get_softc(dev); DPRINTF("frontend_state=%s, xbb_state=%s\n", xenbus_strstate(frontend_state), xenbus_strstate(xenbus_get_state(xbb->dev))); switch (frontend_state) { case XenbusStateInitialising: break; case XenbusStateInitialised: case XenbusStateConnected: xbb_connect(xbb); break; case XenbusStateClosing: case XenbusStateClosed: mtx_lock(&xbb->lock); xbb_shutdown(xbb); mtx_unlock(&xbb->lock); if (frontend_state == XenbusStateClosed) xenbus_set_state(xbb->dev, XenbusStateClosed); break; default: xenbus_dev_fatal(xbb->dev, EINVAL, "saw state %d at frontend", frontend_state); break; } } /*---------------------------- NewBus Registration ---------------------------*/ static device_method_t xbb_methods[] = { /* Device interface */ DEVMETHOD(device_probe, xbb_probe), DEVMETHOD(device_attach, xbb_attach), DEVMETHOD(device_detach, xbb_detach), DEVMETHOD(device_shutdown, bus_generic_shutdown), DEVMETHOD(device_suspend, xbb_suspend), DEVMETHOD(device_resume, xbb_resume), /* Xenbus interface */ DEVMETHOD(xenbus_otherend_changed, xbb_frontend_changed), { 0, 0 } }; static driver_t xbb_driver = { "xbbd", xbb_methods, sizeof(struct xbb_softc), }; devclass_t xbb_devclass; DRIVER_MODULE(xbbd, xenbusb_back, xbb_driver, xbb_devclass, 0, 0);