1 /*
2 * This program is free software; you can redistribute it and/or
3 * modify it under the terms of the GNU General Public License version 2
4 * as published by the Free Software Foundation; or, when distributed
5 * separately from the Linux kernel or incorporated into other
6 * software packages, subject to the following license:
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this source file (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use, copy, modify,
11 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
12 * and to permit persons to whom the Software is furnished to do so, subject to
13 * the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * IN THE SOFTWARE.
25 */
26
27 #ifndef __XEN_BLKIF__BACKEND__COMMON_H__
28 #define __XEN_BLKIF__BACKEND__COMMON_H__
29
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>
36 #include <linux/io.h>
37 #include <linux/rbtree.h>
38 #include <asm/setup.h>
39 #include <asm/hypervisor.h>
40 #include <xen/grant_table.h>
41 #include <xen/page.h>
42 #include <xen/xenbus.h>
43 #include <xen/interface/io/ring.h>
44 #include <xen/interface/io/blkif.h>
45 #include <xen/interface/io/protocols.h>
46
47 extern unsigned int xen_blkif_max_ring_order;
48 extern unsigned int xenblk_max_queues;
49 /*
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.
52 */
53 #define MAX_INDIRECT_SEGMENTS 256
54
55 /*
56 * Xen use 4K pages. The guest may use different page size (4K or 64K)
57 * Number of Xen pages per segment
58 */
59 #define XEN_PAGES_PER_SEGMENT (PAGE_SIZE / XEN_PAGE_SIZE)
60
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)
65
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)
69
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 {
75 char dummy;
76 };
77
78 /* i386 protocol version */
79
80 struct blkif_x86_32_request_rw {
81 uint8_t nr_segments; /* number of segments */
82 blkif_vdev_t handle; /* only for read/write requests */
83 uint64_t id; /* private guest value, echoed in resp */
84 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
85 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
86 } __attribute__((__packed__));
87
88 struct blkif_x86_32_request_discard {
89 uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
90 blkif_vdev_t _pad1; /* was "handle" for read/write requests */
91 uint64_t id; /* private guest value, echoed in resp */
92 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
93 uint64_t nr_sectors;
94 } __attribute__((__packed__));
95
96 struct blkif_x86_32_request_other {
97 uint8_t _pad1;
98 blkif_vdev_t _pad2;
99 uint64_t id; /* private guest value, echoed in resp */
100 } __attribute__((__packed__));
101
102 struct blkif_x86_32_request_indirect {
103 uint8_t indirect_op;
104 uint16_t nr_segments;
105 uint64_t id;
106 blkif_sector_t sector_number;
107 blkif_vdev_t handle;
108 uint16_t _pad1;
109 grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
110 /*
111 * The maximum number of indirect segments (and pages) that will
112 * be used is determined by MAX_INDIRECT_SEGMENTS, this value
113 * is also exported to the guest (via xenstore
114 * feature-max-indirect-segments entry), so the frontend knows how
115 * many indirect segments the backend supports.
116 */
117 uint64_t _pad2; /* make it 64 byte aligned */
118 } __attribute__((__packed__));
119
120 struct blkif_x86_32_request {
121 uint8_t operation; /* BLKIF_OP_??? */
122 union {
123 struct blkif_x86_32_request_rw rw;
124 struct blkif_x86_32_request_discard discard;
125 struct blkif_x86_32_request_other other;
126 struct blkif_x86_32_request_indirect indirect;
127 } u;
128 } __attribute__((__packed__));
129
130 /* x86_64 protocol version */
131
132 struct blkif_x86_64_request_rw {
133 uint8_t nr_segments; /* number of segments */
134 blkif_vdev_t handle; /* only for read/write requests */
135 uint32_t _pad1; /* offsetof(blkif_reqest..,u.rw.id)==8 */
136 uint64_t id;
137 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
138 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
139 } __attribute__((__packed__));
140
141 struct blkif_x86_64_request_discard {
142 uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
143 blkif_vdev_t _pad1; /* was "handle" for read/write requests */
144 uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */
145 uint64_t id;
146 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
147 uint64_t nr_sectors;
148 } __attribute__((__packed__));
149
150 struct blkif_x86_64_request_other {
151 uint8_t _pad1;
152 blkif_vdev_t _pad2;
153 uint32_t _pad3; /* offsetof(blkif_..,u.discard.id)==8 */
154 uint64_t id; /* private guest value, echoed in resp */
155 } __attribute__((__packed__));
156
157 struct blkif_x86_64_request_indirect {
158 uint8_t indirect_op;
159 uint16_t nr_segments;
160 uint32_t _pad1; /* offsetof(blkif_..,u.indirect.id)==8 */
161 uint64_t id;
162 blkif_sector_t sector_number;
163 blkif_vdev_t handle;
164 uint16_t _pad2;
165 grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
166 /*
167 * The maximum number of indirect segments (and pages) that will
168 * be used is determined by MAX_INDIRECT_SEGMENTS, this value
169 * is also exported to the guest (via xenstore
170 * feature-max-indirect-segments entry), so the frontend knows how
171 * many indirect segments the backend supports.
172 */
173 uint32_t _pad3; /* make it 64 byte aligned */
174 } __attribute__((__packed__));
175
176 struct blkif_x86_64_request {
177 uint8_t operation; /* BLKIF_OP_??? */
178 union {
179 struct blkif_x86_64_request_rw rw;
180 struct blkif_x86_64_request_discard discard;
181 struct blkif_x86_64_request_other other;
182 struct blkif_x86_64_request_indirect indirect;
183 } u;
184 } __attribute__((__packed__));
185
186 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
187 struct blkif_response);
188 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
189 struct blkif_response __packed);
190 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
191 struct blkif_response);
192
193 union blkif_back_rings {
194 struct blkif_back_ring native;
195 struct blkif_common_back_ring common;
196 struct blkif_x86_32_back_ring x86_32;
197 struct blkif_x86_64_back_ring x86_64;
198 };
199
200 enum blkif_protocol {
201 BLKIF_PROTOCOL_NATIVE = 1,
202 BLKIF_PROTOCOL_X86_32 = 2,
203 BLKIF_PROTOCOL_X86_64 = 3,
204 };
205
206 /*
207 * Default protocol if the frontend doesn't specify one.
208 */
209 #ifdef CONFIG_X86
210 # define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_X86_32
211 #else
212 # define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_NATIVE
213 #endif
214
215 struct xen_vbd {
216 /* What the domain refers to this vbd as. */
217 blkif_vdev_t handle;
218 /* Non-zero -> read-only */
219 unsigned char readonly;
220 /* VDISK_xxx */
221 unsigned char type;
222 /* phys device that this vbd maps to. */
223 u32 pdevice;
224 struct block_device *bdev;
225 /* Cached size parameter. */
226 sector_t size;
227 unsigned int flush_support:1;
228 unsigned int discard_secure:1;
229 unsigned int feature_gnt_persistent:1;
230 unsigned int overflow_max_grants:1;
231 };
232
233 struct backend_info;
234
235 /* Number of requests that we can fit in a ring */
236 #define XEN_BLKIF_REQS_PER_PAGE 32
237
238 struct persistent_gnt {
239 struct page *page;
240 grant_ref_t gnt;
241 grant_handle_t handle;
242 unsigned long last_used;
243 bool active;
244 struct rb_node node;
245 struct list_head remove_node;
246 };
247
248 /* Per-ring information. */
249 struct xen_blkif_ring {
250 /* Physical parameters of the comms window. */
251 unsigned int irq;
252 union blkif_back_rings blk_rings;
253 void *blk_ring;
254 /* Private fields. */
255 spinlock_t blk_ring_lock;
256
257 wait_queue_head_t wq;
258 atomic_t inflight;
259 bool active;
260 /* One thread per blkif ring. */
261 struct task_struct *xenblkd;
262 unsigned int waiting_reqs;
263
264 /* List of all 'pending_req' available */
265 struct list_head pending_free;
266 /* And its spinlock. */
267 spinlock_t pending_free_lock;
268 wait_queue_head_t pending_free_wq;
269
270 /* Tree to store persistent grants. */
271 struct rb_root persistent_gnts;
272 unsigned int persistent_gnt_c;
273 atomic_t persistent_gnt_in_use;
274 unsigned long next_lru;
275
276 /* Statistics. */
277 unsigned long st_print;
278 unsigned long long st_rd_req;
279 unsigned long long st_wr_req;
280 unsigned long long st_oo_req;
281 unsigned long long st_f_req;
282 unsigned long long st_ds_req;
283 unsigned long long st_rd_sect;
284 unsigned long long st_wr_sect;
285
286 /* Used by the kworker that offload work from the persistent purge. */
287 struct list_head persistent_purge_list;
288 struct work_struct persistent_purge_work;
289
290 /* Buffer of free pages to map grant refs. */
291 struct gnttab_page_cache free_pages;
292
293 struct work_struct free_work;
294 /* Thread shutdown wait queue. */
295 wait_queue_head_t shutdown_wq;
296 struct xen_blkif *blkif;
297 };
298
299 struct xen_blkif {
300 /* Unique identifier for this interface. */
301 domid_t domid;
302 unsigned int handle;
303 /* Comms information. */
304 enum blkif_protocol blk_protocol;
305 /* The VBD attached to this interface. */
306 struct xen_vbd vbd;
307 /* Back pointer to the backend_info. */
308 struct backend_info *be;
309 atomic_t refcnt;
310 /* for barrier (drain) requests */
311 struct completion drain_complete;
312 atomic_t drain;
313
314 struct work_struct free_work;
315 unsigned int nr_ring_pages;
316 /* All rings for this device. */
317 struct xen_blkif_ring *rings;
318 unsigned int nr_rings;
319 unsigned long buffer_squeeze_end;
320 };
321
322 struct seg_buf {
323 unsigned long offset;
324 unsigned int nsec;
325 };
326
327 struct grant_page {
328 struct page *page;
329 struct persistent_gnt *persistent_gnt;
330 grant_handle_t handle;
331 grant_ref_t gref;
332 };
333
334 /*
335 * Each outstanding request that we've passed to the lower device layers has a
336 * 'pending_req' allocated to it. Each buffer_head that completes decrements
337 * the pendcnt towards zero. When it hits zero, the specified domain has a
338 * response queued for it, with the saved 'id' passed back.
339 */
340 struct pending_req {
341 struct xen_blkif_ring *ring;
342 u64 id;
343 int nr_segs;
344 atomic_t pendcnt;
345 unsigned short operation;
346 int status;
347 struct list_head free_list;
348 struct grant_page *segments[MAX_INDIRECT_SEGMENTS];
349 /* Indirect descriptors */
350 struct grant_page *indirect_pages[MAX_INDIRECT_PAGES];
351 struct seg_buf seg[MAX_INDIRECT_SEGMENTS];
352 struct bio *biolist[MAX_INDIRECT_SEGMENTS];
353 struct gnttab_unmap_grant_ref unmap[MAX_INDIRECT_SEGMENTS];
354 struct page *unmap_pages[MAX_INDIRECT_SEGMENTS];
355 struct gntab_unmap_queue_data gnttab_unmap_data;
356 };
357
358
359 #define vbd_sz(_v) ((_v)->bdev->bd_part ? \
360 (_v)->bdev->bd_part->nr_sects : \
361 get_capacity((_v)->bdev->bd_disk))
362
363 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
364 #define xen_blkif_put(_b) \
365 do { \
366 if (atomic_dec_and_test(&(_b)->refcnt)) \
367 schedule_work(&(_b)->free_work);\
368 } while (0)
369
370 struct phys_req {
371 unsigned short dev;
372 blkif_sector_t nr_sects;
373 struct block_device *bdev;
374 blkif_sector_t sector_number;
375 };
376
377 int xen_blkif_interface_init(void);
378 void xen_blkif_interface_fini(void);
379
380 int xen_blkif_xenbus_init(void);
381 void xen_blkif_xenbus_fini(void);
382
383 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
384 int xen_blkif_schedule(void *arg);
385 int xen_blkif_purge_persistent(void *arg);
386 void xen_blkbk_free_caches(struct xen_blkif_ring *ring);
387
388 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
389 struct backend_info *be, int state);
390
391 int xen_blkbk_barrier(struct xenbus_transaction xbt,
392 struct backend_info *be, int state);
393 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
394 void xen_blkbk_unmap_purged_grants(struct work_struct *work);
395
blkif_get_x86_32_req(struct blkif_request * dst,struct blkif_x86_32_request * src)396 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
397 struct blkif_x86_32_request *src)
398 {
399 int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
400 dst->operation = READ_ONCE(src->operation);
401 switch (dst->operation) {
402 case BLKIF_OP_READ:
403 case BLKIF_OP_WRITE:
404 case BLKIF_OP_WRITE_BARRIER:
405 case BLKIF_OP_FLUSH_DISKCACHE:
406 dst->u.rw.nr_segments = src->u.rw.nr_segments;
407 dst->u.rw.handle = src->u.rw.handle;
408 dst->u.rw.id = src->u.rw.id;
409 dst->u.rw.sector_number = src->u.rw.sector_number;
410 barrier();
411 if (n > dst->u.rw.nr_segments)
412 n = dst->u.rw.nr_segments;
413 for (i = 0; i < n; i++)
414 dst->u.rw.seg[i] = src->u.rw.seg[i];
415 break;
416 case BLKIF_OP_DISCARD:
417 dst->u.discard.flag = src->u.discard.flag;
418 dst->u.discard.id = src->u.discard.id;
419 dst->u.discard.sector_number = src->u.discard.sector_number;
420 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
421 break;
422 case BLKIF_OP_INDIRECT:
423 dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
424 dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
425 dst->u.indirect.handle = src->u.indirect.handle;
426 dst->u.indirect.id = src->u.indirect.id;
427 dst->u.indirect.sector_number = src->u.indirect.sector_number;
428 barrier();
429 j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
430 for (i = 0; i < j; i++)
431 dst->u.indirect.indirect_grefs[i] =
432 src->u.indirect.indirect_grefs[i];
433 break;
434 default:
435 /*
436 * Don't know how to translate this op. Only get the
437 * ID so failure can be reported to the frontend.
438 */
439 dst->u.other.id = src->u.other.id;
440 break;
441 }
442 }
443
blkif_get_x86_64_req(struct blkif_request * dst,struct blkif_x86_64_request * src)444 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
445 struct blkif_x86_64_request *src)
446 {
447 int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
448 dst->operation = READ_ONCE(src->operation);
449 switch (dst->operation) {
450 case BLKIF_OP_READ:
451 case BLKIF_OP_WRITE:
452 case BLKIF_OP_WRITE_BARRIER:
453 case BLKIF_OP_FLUSH_DISKCACHE:
454 dst->u.rw.nr_segments = src->u.rw.nr_segments;
455 dst->u.rw.handle = src->u.rw.handle;
456 dst->u.rw.id = src->u.rw.id;
457 dst->u.rw.sector_number = src->u.rw.sector_number;
458 barrier();
459 if (n > dst->u.rw.nr_segments)
460 n = dst->u.rw.nr_segments;
461 for (i = 0; i < n; i++)
462 dst->u.rw.seg[i] = src->u.rw.seg[i];
463 break;
464 case BLKIF_OP_DISCARD:
465 dst->u.discard.flag = src->u.discard.flag;
466 dst->u.discard.id = src->u.discard.id;
467 dst->u.discard.sector_number = src->u.discard.sector_number;
468 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
469 break;
470 case BLKIF_OP_INDIRECT:
471 dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
472 dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
473 dst->u.indirect.handle = src->u.indirect.handle;
474 dst->u.indirect.id = src->u.indirect.id;
475 dst->u.indirect.sector_number = src->u.indirect.sector_number;
476 barrier();
477 j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
478 for (i = 0; i < j; i++)
479 dst->u.indirect.indirect_grefs[i] =
480 src->u.indirect.indirect_grefs[i];
481 break;
482 default:
483 /*
484 * Don't know how to translate this op. Only get the
485 * ID so failure can be reported to the frontend.
486 */
487 dst->u.other.id = src->u.other.id;
488 break;
489 }
490 }
491
492 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */
493
