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27 #ifndef __XEN_BLKIF__BACKEND__COMMON_H__
28 #define __XEN_BLKIF__BACKEND__COMMON_H__
30 #include <linux/module.h>
31 #include <linux/interrupt.h>
32 #include <linux/slab.h>
33 #include <linux/blkdev.h>
34 #include <linux/vmalloc.h>
35 #include <linux/wait.h>
37 #include <linux/rbtree.h>
38 #include <asm/setup.h>
39 #include <asm/pgalloc.h>
40 #include <asm/hypervisor.h>
41 #include <xen/grant_table.h>
43 #include <xen/xenbus.h>
44 #include <xen/interface/io/ring.h>
45 #include <xen/interface/io/blkif.h>
46 #include <xen/interface/io/protocols.h>
48 extern unsigned int xen_blkif_max_ring_order;
50 * This is the maximum number of segments that would be allowed in indirect
51 * requests. This value will also be passed to the frontend.
53 #define MAX_INDIRECT_SEGMENTS 256
56 * Xen use 4K pages. The guest may use different page size (4K or 64K)
57 * Number of Xen pages per segment
59 #define XEN_PAGES_PER_SEGMENT (PAGE_SIZE / XEN_PAGE_SIZE)
61 #define XEN_PAGES_PER_INDIRECT_FRAME \
62 (XEN_PAGE_SIZE/sizeof(struct blkif_request_segment))
63 #define SEGS_PER_INDIRECT_FRAME \
64 (XEN_PAGES_PER_INDIRECT_FRAME / XEN_PAGES_PER_SEGMENT)
66 #define MAX_INDIRECT_PAGES \
67 ((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
68 #define INDIRECT_PAGES(_segs) DIV_ROUND_UP(_segs, XEN_PAGES_PER_INDIRECT_FRAME)
70 /* Not a real protocol. Used to generate ring structs which contain
71 * the elements common to all protocols only. This way we get a
72 * compiler-checkable way to use common struct elements, so we can
73 * avoid using switch(protocol) in a number of places. */
74 struct blkif_common_request {
77 struct blkif_common_response {
81 struct blkif_x86_32_request_rw {
82 uint8_t nr_segments; /* number of segments */
83 blkif_vdev_t handle; /* only for read/write requests */
84 uint64_t id; /* private guest value, echoed in resp */
85 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
86 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
87 } __attribute__((__packed__));
89 struct blkif_x86_32_request_discard {
90 uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
91 blkif_vdev_t _pad1; /* was "handle" for read/write requests */
92 uint64_t id; /* private guest value, echoed in resp */
93 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
95 } __attribute__((__packed__));
97 struct blkif_x86_32_request_other {
100 uint64_t id; /* private guest value, echoed in resp */
101 } __attribute__((__packed__));
103 struct blkif_x86_32_request_indirect {
105 uint16_t nr_segments;
107 blkif_sector_t sector_number;
110 grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
112 * The maximum number of indirect segments (and pages) that will
113 * be used is determined by MAX_INDIRECT_SEGMENTS, this value
114 * is also exported to the guest (via xenstore
115 * feature-max-indirect-segments entry), so the frontend knows how
116 * many indirect segments the backend supports.
118 uint64_t _pad2; /* make it 64 byte aligned */
119 } __attribute__((__packed__));
121 struct blkif_x86_32_request {
122 uint8_t operation; /* BLKIF_OP_??? */
124 struct blkif_x86_32_request_rw rw;
125 struct blkif_x86_32_request_discard discard;
126 struct blkif_x86_32_request_other other;
127 struct blkif_x86_32_request_indirect indirect;
129 } __attribute__((__packed__));
131 /* i386 protocol version */
132 #pragma pack(push, 4)
133 struct blkif_x86_32_response {
134 uint64_t id; /* copied from request */
135 uint8_t operation; /* copied from request */
136 int16_t status; /* BLKIF_RSP_??? */
139 /* x86_64 protocol version */
141 struct blkif_x86_64_request_rw {
142 uint8_t nr_segments; /* number of segments */
143 blkif_vdev_t handle; /* only for read/write requests */
144 uint32_t _pad1; /* offsetof(blkif_reqest..,u.rw.id)==8 */
146 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
147 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
148 } __attribute__((__packed__));
150 struct blkif_x86_64_request_discard {
151 uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
152 blkif_vdev_t _pad1; /* was "handle" for read/write requests */
153 uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */
155 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
157 } __attribute__((__packed__));
159 struct blkif_x86_64_request_other {
162 uint32_t _pad3; /* offsetof(blkif_..,u.discard.id)==8 */
163 uint64_t id; /* private guest value, echoed in resp */
164 } __attribute__((__packed__));
166 struct blkif_x86_64_request_indirect {
168 uint16_t nr_segments;
169 uint32_t _pad1; /* offsetof(blkif_..,u.indirect.id)==8 */
171 blkif_sector_t sector_number;
174 grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
176 * The maximum number of indirect segments (and pages) that will
177 * be used is determined by MAX_INDIRECT_SEGMENTS, this value
178 * is also exported to the guest (via xenstore
179 * feature-max-indirect-segments entry), so the frontend knows how
180 * many indirect segments the backend supports.
182 uint32_t _pad3; /* make it 64 byte aligned */
183 } __attribute__((__packed__));
185 struct blkif_x86_64_request {
186 uint8_t operation; /* BLKIF_OP_??? */
188 struct blkif_x86_64_request_rw rw;
189 struct blkif_x86_64_request_discard discard;
190 struct blkif_x86_64_request_other other;
191 struct blkif_x86_64_request_indirect indirect;
193 } __attribute__((__packed__));
195 struct blkif_x86_64_response {
196 uint64_t __attribute__((__aligned__(8))) id;
197 uint8_t operation; /* copied from request */
198 int16_t status; /* BLKIF_RSP_??? */
201 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
202 struct blkif_common_response);
203 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
204 struct blkif_x86_32_response);
205 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
206 struct blkif_x86_64_response);
208 union blkif_back_rings {
209 struct blkif_back_ring native;
210 struct blkif_common_back_ring common;
211 struct blkif_x86_32_back_ring x86_32;
212 struct blkif_x86_64_back_ring x86_64;
215 enum blkif_protocol {
216 BLKIF_PROTOCOL_NATIVE = 1,
217 BLKIF_PROTOCOL_X86_32 = 2,
218 BLKIF_PROTOCOL_X86_64 = 3,
222 * Default protocol if the frontend doesn't specify one.
225 # define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_X86_32
227 # define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_NATIVE
231 /* What the domain refers to this vbd as. */
233 /* Non-zero -> read-only */
234 unsigned char readonly;
237 /* phys device that this vbd maps to. */
239 struct block_device *bdev;
240 /* Cached size parameter. */
242 unsigned int flush_support:1;
243 unsigned int discard_secure:1;
244 unsigned int feature_gnt_persistent:1;
245 unsigned int overflow_max_grants:1;
250 /* Number of available flags */
251 #define PERSISTENT_GNT_FLAGS_SIZE 2
252 /* This persistent grant is currently in use */
253 #define PERSISTENT_GNT_ACTIVE 0
255 * This persistent grant has been used, this flag is set when we remove the
256 * PERSISTENT_GNT_ACTIVE, to know that this grant has been used recently.
258 #define PERSISTENT_GNT_WAS_ACTIVE 1
260 /* Number of requests that we can fit in a ring */
261 #define XEN_BLKIF_REQS_PER_PAGE 32
263 struct persistent_gnt {
266 grant_handle_t handle;
267 DECLARE_BITMAP(flags, PERSISTENT_GNT_FLAGS_SIZE);
269 struct list_head remove_node;
272 /* Per-ring information. */
273 struct xen_blkif_ring {
274 /* Physical parameters of the comms window. */
276 union blkif_back_rings blk_rings;
278 /* Private fields. */
279 spinlock_t blk_ring_lock;
281 wait_queue_head_t wq;
283 /* One thread per blkif ring. */
284 struct task_struct *xenblkd;
285 unsigned int waiting_reqs;
287 /* List of all 'pending_req' available */
288 struct list_head pending_free;
289 /* And its spinlock. */
290 spinlock_t pending_free_lock;
291 wait_queue_head_t pending_free_wq;
293 struct work_struct free_work;
294 /* Thread shutdown wait queue. */
295 wait_queue_head_t shutdown_wq;
296 struct xen_blkif *blkif;
300 /* Unique identifier for this interface. */
303 /* Comms information. */
304 enum blkif_protocol blk_protocol;
305 /* The VBD attached to this interface. */
307 /* Back pointer to the backend_info. */
308 struct backend_info *be;
310 /* for barrier (drain) requests */
311 struct completion drain_complete;
314 /* tree to store persistent grants */
315 spinlock_t pers_gnts_lock;
316 struct rb_root persistent_gnts;
317 unsigned int persistent_gnt_c;
318 atomic_t persistent_gnt_in_use;
319 unsigned long next_lru;
321 /* used by the kworker that offload work from the persistent purge */
322 struct list_head persistent_purge_list;
323 struct work_struct persistent_purge_work;
325 /* buffer of free pages to map grant refs */
326 spinlock_t free_pages_lock;
328 struct list_head free_pages;
331 unsigned long st_print;
332 unsigned long long st_rd_req;
333 unsigned long long st_wr_req;
334 unsigned long long st_oo_req;
335 unsigned long long st_f_req;
336 unsigned long long st_ds_req;
337 unsigned long long st_rd_sect;
338 unsigned long long st_wr_sect;
340 struct work_struct free_work;
341 unsigned int nr_ring_pages;
342 /* All rings for this device. */
343 struct xen_blkif_ring *rings;
344 unsigned int nr_rings;
348 unsigned long offset;
354 struct persistent_gnt *persistent_gnt;
355 grant_handle_t handle;
360 * Each outstanding request that we've passed to the lower device layers has a
361 * 'pending_req' allocated to it. Each buffer_head that completes decrements
362 * the pendcnt towards zero. When it hits zero, the specified domain has a
363 * response queued for it, with the saved 'id' passed back.
366 struct xen_blkif_ring *ring;
370 unsigned short operation;
372 struct list_head free_list;
373 struct grant_page *segments[MAX_INDIRECT_SEGMENTS];
374 /* Indirect descriptors */
375 struct grant_page *indirect_pages[MAX_INDIRECT_PAGES];
376 struct seg_buf seg[MAX_INDIRECT_SEGMENTS];
377 struct bio *biolist[MAX_INDIRECT_SEGMENTS];
378 struct gnttab_unmap_grant_ref unmap[MAX_INDIRECT_SEGMENTS];
379 struct page *unmap_pages[MAX_INDIRECT_SEGMENTS];
380 struct gntab_unmap_queue_data gnttab_unmap_data;
384 #define vbd_sz(_v) ((_v)->bdev->bd_part ? \
385 (_v)->bdev->bd_part->nr_sects : \
386 get_capacity((_v)->bdev->bd_disk))
388 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
389 #define xen_blkif_put(_b) \
391 if (atomic_dec_and_test(&(_b)->refcnt)) \
392 schedule_work(&(_b)->free_work);\
397 blkif_sector_t nr_sects;
398 struct block_device *bdev;
399 blkif_sector_t sector_number;
401 int xen_blkif_interface_init(void);
403 int xen_blkif_xenbus_init(void);
405 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
406 int xen_blkif_schedule(void *arg);
407 int xen_blkif_purge_persistent(void *arg);
408 void xen_blkbk_free_caches(struct xen_blkif_ring *ring);
410 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
411 struct backend_info *be, int state);
413 int xen_blkbk_barrier(struct xenbus_transaction xbt,
414 struct backend_info *be, int state);
415 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
416 void xen_blkbk_unmap_purged_grants(struct work_struct *work);
418 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
419 struct blkif_x86_32_request *src)
421 int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
422 dst->operation = src->operation;
423 switch (src->operation) {
426 case BLKIF_OP_WRITE_BARRIER:
427 case BLKIF_OP_FLUSH_DISKCACHE:
428 dst->u.rw.nr_segments = src->u.rw.nr_segments;
429 dst->u.rw.handle = src->u.rw.handle;
430 dst->u.rw.id = src->u.rw.id;
431 dst->u.rw.sector_number = src->u.rw.sector_number;
433 if (n > dst->u.rw.nr_segments)
434 n = dst->u.rw.nr_segments;
435 for (i = 0; i < n; i++)
436 dst->u.rw.seg[i] = src->u.rw.seg[i];
438 case BLKIF_OP_DISCARD:
439 dst->u.discard.flag = src->u.discard.flag;
440 dst->u.discard.id = src->u.discard.id;
441 dst->u.discard.sector_number = src->u.discard.sector_number;
442 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
444 case BLKIF_OP_INDIRECT:
445 dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
446 dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
447 dst->u.indirect.handle = src->u.indirect.handle;
448 dst->u.indirect.id = src->u.indirect.id;
449 dst->u.indirect.sector_number = src->u.indirect.sector_number;
451 j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
452 for (i = 0; i < j; i++)
453 dst->u.indirect.indirect_grefs[i] =
454 src->u.indirect.indirect_grefs[i];
458 * Don't know how to translate this op. Only get the
459 * ID so failure can be reported to the frontend.
461 dst->u.other.id = src->u.other.id;
466 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
467 struct blkif_x86_64_request *src)
469 int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
470 dst->operation = src->operation;
471 switch (src->operation) {
474 case BLKIF_OP_WRITE_BARRIER:
475 case BLKIF_OP_FLUSH_DISKCACHE:
476 dst->u.rw.nr_segments = src->u.rw.nr_segments;
477 dst->u.rw.handle = src->u.rw.handle;
478 dst->u.rw.id = src->u.rw.id;
479 dst->u.rw.sector_number = src->u.rw.sector_number;
481 if (n > dst->u.rw.nr_segments)
482 n = dst->u.rw.nr_segments;
483 for (i = 0; i < n; i++)
484 dst->u.rw.seg[i] = src->u.rw.seg[i];
486 case BLKIF_OP_DISCARD:
487 dst->u.discard.flag = src->u.discard.flag;
488 dst->u.discard.id = src->u.discard.id;
489 dst->u.discard.sector_number = src->u.discard.sector_number;
490 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
492 case BLKIF_OP_INDIRECT:
493 dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
494 dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
495 dst->u.indirect.handle = src->u.indirect.handle;
496 dst->u.indirect.id = src->u.indirect.id;
497 dst->u.indirect.sector_number = src->u.indirect.sector_number;
499 j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
500 for (i = 0; i < j; i++)
501 dst->u.indirect.indirect_grefs[i] =
502 src->u.indirect.indirect_grefs[i];
506 * Don't know how to translate this op. Only get the
507 * ID so failure can be reported to the frontend.
509 dst->u.other.id = src->u.other.id;
514 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */