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-rw-r--r--drivers/block/xen-blkback/common.h494
1 files changed, 494 insertions, 0 deletions
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
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+++ b/drivers/block/xen-blkback/common.h
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+/*
+ * 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__ */