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Diffstat (limited to 'drivers/block/xen-blkback/common.h')
| -rw-r--r-- | drivers/block/xen-blkback/common.h | 494 |
1 files changed, 494 insertions, 0 deletions
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h new file mode 100644 index 000000000..a28473470 --- /dev/null +++ b/drivers/block/xen-blkback/common.h @@ -0,0 +1,494 @@ +/* + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License version 2 + * as published by the Free Software Foundation; or, when distributed + * separately from the Linux kernel or incorporated into other + * software packages, subject to the following license: + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this source file (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, modify, + * merge, publish, distribute, sublicense, and/or sell copies of the Software, + * and to permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + */ + +#ifndef __XEN_BLKIF__BACKEND__COMMON_H__ +#define __XEN_BLKIF__BACKEND__COMMON_H__ + +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/slab.h> +#include <linux/blkdev.h> +#include <linux/vmalloc.h> +#include <linux/wait.h> +#include <linux/io.h> +#include <linux/rbtree.h> +#include <asm/setup.h> +#include <asm/hypervisor.h> +#include <xen/grant_table.h> +#include <xen/page.h> +#include <xen/xenbus.h> +#include <xen/interface/io/ring.h> +#include <xen/interface/io/blkif.h> +#include <xen/interface/io/protocols.h> + +extern unsigned int xen_blkif_max_ring_order; +extern unsigned int xenblk_max_queues; +/* + * This is the maximum number of segments that would be allowed in indirect + * requests. This value will also be passed to the frontend. + */ +#define MAX_INDIRECT_SEGMENTS 256 + +/* + * Xen use 4K pages. The guest may use different page size (4K or 64K) + * Number of Xen pages per segment + */ +#define XEN_PAGES_PER_SEGMENT (PAGE_SIZE / XEN_PAGE_SIZE) + +#define XEN_PAGES_PER_INDIRECT_FRAME \ + (XEN_PAGE_SIZE/sizeof(struct blkif_request_segment)) +#define SEGS_PER_INDIRECT_FRAME \ + (XEN_PAGES_PER_INDIRECT_FRAME / XEN_PAGES_PER_SEGMENT) + +#define MAX_INDIRECT_PAGES \ + ((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME) +#define INDIRECT_PAGES(_segs) DIV_ROUND_UP(_segs, XEN_PAGES_PER_INDIRECT_FRAME) + +/* Not a real protocol. Used to generate ring structs which contain + * the elements common to all protocols only. This way we get a + * compiler-checkable way to use common struct elements, so we can + * avoid using switch(protocol) in a number of places. */ +struct blkif_common_request { + char dummy; +}; + +/* i386 protocol version */ + +struct blkif_x86_32_request_rw { + uint8_t nr_segments; /* number of segments */ + blkif_vdev_t handle; /* only for read/write requests */ + uint64_t id; /* private guest value, echoed in resp */ + blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ + struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; +} __attribute__((__packed__)); + +struct blkif_x86_32_request_discard { + uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */ + blkif_vdev_t _pad1; /* was "handle" for read/write requests */ + uint64_t id; /* private guest value, echoed in resp */ + blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ + uint64_t nr_sectors; +} __attribute__((__packed__)); + +struct blkif_x86_32_request_other { + uint8_t _pad1; + blkif_vdev_t _pad2; + uint64_t id; /* private guest value, echoed in resp */ +} __attribute__((__packed__)); + +struct blkif_x86_32_request_indirect { + uint8_t indirect_op; + uint16_t nr_segments; + uint64_t id; + blkif_sector_t sector_number; + blkif_vdev_t handle; + uint16_t _pad1; + grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST]; + /* + * The maximum number of indirect segments (and pages) that will + * be used is determined by MAX_INDIRECT_SEGMENTS, this value + * is also exported to the guest (via xenstore + * feature-max-indirect-segments entry), so the frontend knows how + * many indirect segments the backend supports. + */ + uint64_t _pad2; /* make it 64 byte aligned */ +} __attribute__((__packed__)); + +struct blkif_x86_32_request { + uint8_t operation; /* BLKIF_OP_??? */ + union { + struct blkif_x86_32_request_rw rw; + struct blkif_x86_32_request_discard discard; + struct blkif_x86_32_request_other other; + struct blkif_x86_32_request_indirect indirect; + } u; +} __attribute__((__packed__)); + +/* x86_64 protocol version */ + +struct blkif_x86_64_request_rw { + uint8_t nr_segments; /* number of segments */ + blkif_vdev_t handle; /* only for read/write requests */ + uint32_t _pad1; /* offsetof(blkif_reqest..,u.rw.id)==8 */ + uint64_t id; + blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ + struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; +} __attribute__((__packed__)); + +struct blkif_x86_64_request_discard { + uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */ + blkif_vdev_t _pad1; /* was "handle" for read/write requests */ + uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */ + uint64_t id; + blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ + uint64_t nr_sectors; +} __attribute__((__packed__)); + +struct blkif_x86_64_request_other { + uint8_t _pad1; + blkif_vdev_t _pad2; + uint32_t _pad3; /* offsetof(blkif_..,u.discard.id)==8 */ + uint64_t id; /* private guest value, echoed in resp */ +} __attribute__((__packed__)); + +struct blkif_x86_64_request_indirect { + uint8_t indirect_op; + uint16_t nr_segments; + uint32_t _pad1; /* offsetof(blkif_..,u.indirect.id)==8 */ + uint64_t id; + blkif_sector_t sector_number; + blkif_vdev_t handle; + uint16_t _pad2; + grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST]; + /* + * The maximum number of indirect segments (and pages) that will + * be used is determined by MAX_INDIRECT_SEGMENTS, this value + * is also exported to the guest (via xenstore + * feature-max-indirect-segments entry), so the frontend knows how + * many indirect segments the backend supports. + */ + uint32_t _pad3; /* make it 64 byte aligned */ +} __attribute__((__packed__)); + +struct blkif_x86_64_request { + uint8_t operation; /* BLKIF_OP_??? */ + union { + struct blkif_x86_64_request_rw rw; + struct blkif_x86_64_request_discard discard; + struct blkif_x86_64_request_other other; + struct blkif_x86_64_request_indirect indirect; + } u; +} __attribute__((__packed__)); + +DEFINE_RING_TYPES(blkif_common, struct blkif_common_request, + struct blkif_response); +DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, + struct blkif_response __packed); +DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, + struct blkif_response); + +union blkif_back_rings { + struct blkif_back_ring native; + struct blkif_common_back_ring common; + struct blkif_x86_32_back_ring x86_32; + struct blkif_x86_64_back_ring x86_64; +}; + +enum blkif_protocol { + BLKIF_PROTOCOL_NATIVE = 1, + BLKIF_PROTOCOL_X86_32 = 2, + BLKIF_PROTOCOL_X86_64 = 3, +}; + +/* + * Default protocol if the frontend doesn't specify one. + */ +#ifdef CONFIG_X86 +# define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_X86_32 +#else +# define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_NATIVE +#endif + +struct xen_vbd { + /* What the domain refers to this vbd as. */ + blkif_vdev_t handle; + /* Non-zero -> read-only */ + unsigned char readonly; + /* VDISK_xxx */ + unsigned char type; + /* phys device that this vbd maps to. */ + u32 pdevice; + struct block_device *bdev; + /* Cached size parameter. */ + sector_t size; + unsigned int flush_support:1; + unsigned int discard_secure:1; + /* Connect-time cached feature_persistent parameter value */ + unsigned int feature_gnt_persistent_parm:1; + /* Persistent grants feature negotiation result */ + unsigned int feature_gnt_persistent:1; + unsigned int overflow_max_grants:1; +}; + +struct backend_info; + +/* Number of requests that we can fit in a ring */ +#define XEN_BLKIF_REQS_PER_PAGE 32 + +struct persistent_gnt { + struct page *page; + grant_ref_t gnt; + grant_handle_t handle; + unsigned long last_used; + bool active; + struct rb_node node; + struct list_head remove_node; +}; + +/* Per-ring information. */ +struct xen_blkif_ring { + /* Physical parameters of the comms window. */ + unsigned int irq; + union blkif_back_rings blk_rings; + void *blk_ring; + /* Private fields. */ + spinlock_t blk_ring_lock; + + wait_queue_head_t wq; + atomic_t inflight; + bool active; + /* One thread per blkif ring. */ + struct task_struct *xenblkd; + unsigned int waiting_reqs; + + /* List of all 'pending_req' available */ + struct list_head pending_free; + /* And its spinlock. */ + spinlock_t pending_free_lock; + wait_queue_head_t pending_free_wq; + + /* Tree to store persistent grants. */ + struct rb_root persistent_gnts; + unsigned int persistent_gnt_c; + atomic_t persistent_gnt_in_use; + unsigned long next_lru; + + /* Statistics. */ + unsigned long st_print; + unsigned long long st_rd_req; + unsigned long long st_wr_req; + unsigned long long st_oo_req; + unsigned long long st_f_req; + unsigned long long st_ds_req; + unsigned long long st_rd_sect; + unsigned long long st_wr_sect; + + /* Used by the kworker that offload work from the persistent purge. */ + struct list_head persistent_purge_list; + struct work_struct persistent_purge_work; + + /* Buffer of free pages to map grant refs. */ + struct gnttab_page_cache free_pages; + + struct work_struct free_work; + /* Thread shutdown wait queue. */ + wait_queue_head_t shutdown_wq; + struct xen_blkif *blkif; +}; + +struct xen_blkif { + /* Unique identifier for this interface. */ + domid_t domid; + unsigned int handle; + /* Comms information. */ + enum blkif_protocol blk_protocol; + /* The VBD attached to this interface. */ + struct xen_vbd vbd; + /* Back pointer to the backend_info. */ + struct backend_info *be; + atomic_t refcnt; + /* for barrier (drain) requests */ + struct completion drain_complete; + atomic_t drain; + + struct work_struct free_work; + unsigned int nr_ring_pages; + bool multi_ref; + /* All rings for this device. */ + struct xen_blkif_ring *rings; + unsigned int nr_rings; + unsigned long buffer_squeeze_end; +}; + +struct seg_buf { + unsigned long offset; + unsigned int nsec; +}; + +struct grant_page { + struct page *page; + struct persistent_gnt *persistent_gnt; + grant_handle_t handle; + grant_ref_t gref; +}; + +/* + * Each outstanding request that we've passed to the lower device layers has a + * 'pending_req' allocated to it. Each buffer_head that completes decrements + * the pendcnt towards zero. When it hits zero, the specified domain has a + * response queued for it, with the saved 'id' passed back. + */ +struct pending_req { + struct xen_blkif_ring *ring; + u64 id; + int nr_segs; + atomic_t pendcnt; + unsigned short operation; + int status; + struct list_head free_list; + struct grant_page *segments[MAX_INDIRECT_SEGMENTS]; + /* Indirect descriptors */ + struct grant_page *indirect_pages[MAX_INDIRECT_PAGES]; + struct seg_buf seg[MAX_INDIRECT_SEGMENTS]; + struct bio *biolist[MAX_INDIRECT_SEGMENTS]; + struct gnttab_unmap_grant_ref unmap[MAX_INDIRECT_SEGMENTS]; + struct page *unmap_pages[MAX_INDIRECT_SEGMENTS]; + struct gntab_unmap_queue_data gnttab_unmap_data; +}; + + +#define vbd_sz(_v) bdev_nr_sectors((_v)->bdev) + +#define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt)) +#define xen_blkif_put(_b) \ + do { \ + if (atomic_dec_and_test(&(_b)->refcnt)) \ + schedule_work(&(_b)->free_work);\ + } while (0) + +struct phys_req { + unsigned short dev; + blkif_sector_t nr_sects; + struct block_device *bdev; + blkif_sector_t sector_number; +}; + +int xen_blkif_interface_init(void); +void xen_blkif_interface_fini(void); + +int xen_blkif_xenbus_init(void); +void xen_blkif_xenbus_fini(void); + +irqreturn_t xen_blkif_be_int(int irq, void *dev_id); +int xen_blkif_schedule(void *arg); +int xen_blkif_purge_persistent(void *arg); +void xen_blkbk_free_caches(struct xen_blkif_ring *ring); + +int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt, + struct backend_info *be, int state); + +int xen_blkbk_barrier(struct xenbus_transaction xbt, + struct backend_info *be, int state); +struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be); +void xen_blkbk_unmap_purged_grants(struct work_struct *work); + +static inline void blkif_get_x86_32_req(struct blkif_request *dst, + struct blkif_x86_32_request *src) +{ + int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j; + dst->operation = READ_ONCE(src->operation); + switch (dst->operation) { + case BLKIF_OP_READ: + case BLKIF_OP_WRITE: + case BLKIF_OP_WRITE_BARRIER: + case BLKIF_OP_FLUSH_DISKCACHE: + dst->u.rw.nr_segments = src->u.rw.nr_segments; + dst->u.rw.handle = src->u.rw.handle; + dst->u.rw.id = src->u.rw.id; + dst->u.rw.sector_number = src->u.rw.sector_number; + barrier(); + if (n > dst->u.rw.nr_segments) + n = dst->u.rw.nr_segments; + for (i = 0; i < n; i++) + dst->u.rw.seg[i] = src->u.rw.seg[i]; + break; + case BLKIF_OP_DISCARD: + dst->u.discard.flag = src->u.discard.flag; + dst->u.discard.id = src->u.discard.id; + dst->u.discard.sector_number = src->u.discard.sector_number; + dst->u.discard.nr_sectors = src->u.discard.nr_sectors; + break; + case BLKIF_OP_INDIRECT: + dst->u.indirect.indirect_op = src->u.indirect.indirect_op; + dst->u.indirect.nr_segments = src->u.indirect.nr_segments; + dst->u.indirect.handle = src->u.indirect.handle; + dst->u.indirect.id = src->u.indirect.id; + dst->u.indirect.sector_number = src->u.indirect.sector_number; + barrier(); + j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments)); + for (i = 0; i < j; i++) + dst->u.indirect.indirect_grefs[i] = + src->u.indirect.indirect_grefs[i]; + break; + default: + /* + * Don't know how to translate this op. Only get the + * ID so failure can be reported to the frontend. + */ + dst->u.other.id = src->u.other.id; + break; + } +} + +static inline void blkif_get_x86_64_req(struct blkif_request *dst, + struct blkif_x86_64_request *src) +{ + int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j; + dst->operation = READ_ONCE(src->operation); + switch (dst->operation) { + case BLKIF_OP_READ: + case BLKIF_OP_WRITE: + case BLKIF_OP_WRITE_BARRIER: + case BLKIF_OP_FLUSH_DISKCACHE: + dst->u.rw.nr_segments = src->u.rw.nr_segments; + dst->u.rw.handle = src->u.rw.handle; + dst->u.rw.id = src->u.rw.id; + dst->u.rw.sector_number = src->u.rw.sector_number; + barrier(); + if (n > dst->u.rw.nr_segments) + n = dst->u.rw.nr_segments; + for (i = 0; i < n; i++) + dst->u.rw.seg[i] = src->u.rw.seg[i]; + break; + case BLKIF_OP_DISCARD: + dst->u.discard.flag = src->u.discard.flag; + dst->u.discard.id = src->u.discard.id; + dst->u.discard.sector_number = src->u.discard.sector_number; + dst->u.discard.nr_sectors = src->u.discard.nr_sectors; + break; + case BLKIF_OP_INDIRECT: + dst->u.indirect.indirect_op = src->u.indirect.indirect_op; + dst->u.indirect.nr_segments = src->u.indirect.nr_segments; + dst->u.indirect.handle = src->u.indirect.handle; + dst->u.indirect.id = src->u.indirect.id; + dst->u.indirect.sector_number = src->u.indirect.sector_number; + barrier(); + j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments)); + for (i = 0; i < j; i++) + dst->u.indirect.indirect_grefs[i] = + src->u.indirect.indirect_grefs[i]; + break; + default: + /* + * Don't know how to translate this op. Only get the + * ID so failure can be reported to the frontend. + */ + dst->u.other.id = src->u.other.id; + break; + } +} + +#endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */ |