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/pgalloc.h>
40 #include <asm/hypervisor.h>
41 #include <xen/grant_table.h>
42 #include <xen/page.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>
47
48 extern unsigned int xen_blkif_max_ring_order;
49 extern unsigned int xenblk_max_queues;
50 /*
51 * This is the maximum number of segments that would be allowed in indirect
52 * requests. This value will also be passed to the frontend.
53 */
54 #define MAX_INDIRECT_SEGMENTS 256
55
56 /*
57 * Xen use 4K pages. The guest may use different page size (4K or 64K)
58 * Number of Xen pages per segment
59 */
60 #define XEN_PAGES_PER_SEGMENT (PAGE_SIZE / XEN_PAGE_SIZE)
61
62 #define XEN_PAGES_PER_INDIRECT_FRAME \
63 (XEN_PAGE_SIZE/sizeof(struct blkif_request_segment))
64 #define SEGS_PER_INDIRECT_FRAME \
65 (XEN_PAGES_PER_INDIRECT_FRAME / XEN_PAGES_PER_SEGMENT)
66
67 #define MAX_INDIRECT_PAGES \
68 ((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
69 #define INDIRECT_PAGES(_segs) DIV_ROUND_UP(_segs, XEN_PAGES_PER_INDIRECT_FRAME)
70
71 /* Not a real protocol. Used to generate ring structs which contain
72 * the elements common to all protocols only. This way we get a
73 * compiler-checkable way to use common struct elements, so we can
74 * avoid using switch(protocol) in a number of places. */
75 struct blkif_common_request {
76 char dummy;
77 };
78
79 /* i386 protocol version */
80
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__));
88
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) */
94 uint64_t nr_sectors;
95 } __attribute__((__packed__));
96
97 struct blkif_x86_32_request_other {
98 uint8_t _pad1;
99 blkif_vdev_t _pad2;
100 uint64_t id; /* private guest value, echoed in resp */
101 } __attribute__((__packed__));
102
103 struct blkif_x86_32_request_indirect {
104 uint8_t indirect_op;
105 uint16_t nr_segments;
106 uint64_t id;
107 blkif_sector_t sector_number;
108 blkif_vdev_t handle;
109 uint16_t _pad1;
110 grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
111 /*
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.
117 */
118 uint64_t _pad2; /* make it 64 byte aligned */
119 } __attribute__((__packed__));
120
121 struct blkif_x86_32_request {
122 uint8_t operation; /* BLKIF_OP_??? */
123 union {
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;
128 } u;
129 } __attribute__((__packed__));
130
131 /* x86_64 protocol version */
132
133 struct blkif_x86_64_request_rw {
134 uint8_t nr_segments; /* number of segments */
135 blkif_vdev_t handle; /* only for read/write requests */
136 uint32_t _pad1; /* offsetof(blkif_reqest..,u.rw.id)==8 */
137 uint64_t id;
138 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
139 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
140 } __attribute__((__packed__));
141
142 struct blkif_x86_64_request_discard {
143 uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
144 blkif_vdev_t _pad1; /* was "handle" for read/write requests */
145 uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */
146 uint64_t id;
147 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
148 uint64_t nr_sectors;
149 } __attribute__((__packed__));
150
151 struct blkif_x86_64_request_other {
152 uint8_t _pad1;
153 blkif_vdev_t _pad2;
154 uint32_t _pad3; /* offsetof(blkif_..,u.discard.id)==8 */
155 uint64_t id; /* private guest value, echoed in resp */
156 } __attribute__((__packed__));
157
158 struct blkif_x86_64_request_indirect {
159 uint8_t indirect_op;
160 uint16_t nr_segments;
161 uint32_t _pad1; /* offsetof(blkif_..,u.indirect.id)==8 */
162 uint64_t id;
163 blkif_sector_t sector_number;
164 blkif_vdev_t handle;
165 uint16_t _pad2;
166 grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
167 /*
168 * The maximum number of indirect segments (and pages) that will
169 * be used is determined by MAX_INDIRECT_SEGMENTS, this value
170 * is also exported to the guest (via xenstore
171 * feature-max-indirect-segments entry), so the frontend knows how
172 * many indirect segments the backend supports.
173 */
174 uint32_t _pad3; /* make it 64 byte aligned */
175 } __attribute__((__packed__));
176
177 struct blkif_x86_64_request {
178 uint8_t operation; /* BLKIF_OP_??? */
179 union {
180 struct blkif_x86_64_request_rw rw;
181 struct blkif_x86_64_request_discard discard;
182 struct blkif_x86_64_request_other other;
183 struct blkif_x86_64_request_indirect indirect;
184 } u;
185 } __attribute__((__packed__));
186
187 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
188 struct blkif_response);
189 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
190 struct blkif_response __packed);
191 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
192 struct blkif_response);
193
194 union blkif_back_rings {
195 struct blkif_back_ring native;
196 struct blkif_common_back_ring common;
197 struct blkif_x86_32_back_ring x86_32;
198 struct blkif_x86_64_back_ring x86_64;
199 };
200
201 enum blkif_protocol {
202 BLKIF_PROTOCOL_NATIVE = 1,
203 BLKIF_PROTOCOL_X86_32 = 2,
204 BLKIF_PROTOCOL_X86_64 = 3,
205 };
206
207 /*
208 * Default protocol if the frontend doesn't specify one.
209 */
210 #ifdef CONFIG_X86
211 # define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_X86_32
212 #else
213 # define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_NATIVE
214 #endif
215
216 struct xen_vbd {
217 /* What the domain refers to this vbd as. */
218 blkif_vdev_t handle;
219 /* Non-zero -> read-only */
220 unsigned char readonly;
221 /* VDISK_xxx */
222 unsigned char type;
223 /* phys device that this vbd maps to. */
224 u32 pdevice;
225 struct block_device *bdev;
226 /* Cached size parameter. */
227 sector_t size;
228 unsigned int flush_support:1;
229 unsigned int discard_secure:1;
230 unsigned int feature_gnt_persistent:1;
231 unsigned int overflow_max_grants:1;
232 };
233
234 struct backend_info;
235
236 /* Number of requests that we can fit in a ring */
237 #define XEN_BLKIF_REQS_PER_PAGE 32
238
239 struct persistent_gnt {
240 struct page *page;
241 grant_ref_t gnt;
242 grant_handle_t handle;
243 unsigned long last_used;
244 bool active;
245 struct rb_node node;
246 struct list_head remove_node;
247 };
248
249 /* Per-ring information. */
250 struct xen_blkif_ring {
251 /* Physical parameters of the comms window. */
252 unsigned int irq;
253 union blkif_back_rings blk_rings;
254 void *blk_ring;
255 /* Private fields. */
256 spinlock_t blk_ring_lock;
257
258 wait_queue_head_t wq;
259 atomic_t inflight;
260 bool active;
261 /* One thread per blkif ring. */
262 struct task_struct *xenblkd;
263 unsigned int waiting_reqs;
264
265 /* List of all 'pending_req' available */
266 struct list_head pending_free;
267 /* And its spinlock. */
268 spinlock_t pending_free_lock;
269 wait_queue_head_t pending_free_wq;
270
271 /* Tree to store persistent grants. */
272 struct rb_root persistent_gnts;
273 unsigned int persistent_gnt_c;
274 atomic_t persistent_gnt_in_use;
275 unsigned long next_lru;
276
277 /* Statistics. */
278 unsigned long st_print;
279 unsigned long long st_rd_req;
280 unsigned long long st_wr_req;
281 unsigned long long st_oo_req;
282 unsigned long long st_f_req;
283 unsigned long long st_ds_req;
284 unsigned long long st_rd_sect;
285 unsigned long long st_wr_sect;
286
287 /* Used by the kworker that offload work from the persistent purge. */
288 struct list_head persistent_purge_list;
289 struct work_struct persistent_purge_work;
290
291 /* Buffer of free pages to map grant refs. */
292 spinlock_t free_pages_lock;
293 int free_pages_num;
294 struct list_head free_pages;
295
296 struct work_struct free_work;
297 /* Thread shutdown wait queue. */
298 wait_queue_head_t shutdown_wq;
299 struct xen_blkif *blkif;
300 };
301
302 struct xen_blkif {
303 /* Unique identifier for this interface. */
304 domid_t domid;
305 unsigned int handle;
306 /* Comms information. */
307 enum blkif_protocol blk_protocol;
308 /* The VBD attached to this interface. */
309 struct xen_vbd vbd;
310 /* Back pointer to the backend_info. */
311 struct backend_info *be;
312 atomic_t refcnt;
313 /* for barrier (drain) requests */
314 struct completion drain_complete;
315 atomic_t drain;
316
317 struct work_struct free_work;
318 unsigned int nr_ring_pages;
319 /* All rings for this device. */
320 struct xen_blkif_ring *rings;
321 unsigned int nr_rings;
322 };
323
324 struct seg_buf {
325 unsigned long offset;
326 unsigned int nsec;
327 };
328
329 struct grant_page {
330 struct page *page;
331 struct persistent_gnt *persistent_gnt;
332 grant_handle_t handle;
333 grant_ref_t gref;
334 };
335
336 /*
337 * Each outstanding request that we've passed to the lower device layers has a
338 * 'pending_req' allocated to it. Each buffer_head that completes decrements
339 * the pendcnt towards zero. When it hits zero, the specified domain has a
340 * response queued for it, with the saved 'id' passed back.
341 */
342 struct pending_req {
343 struct xen_blkif_ring *ring;
344 u64 id;
345 int nr_segs;
346 atomic_t pendcnt;
347 unsigned short operation;
348 int status;
349 struct list_head free_list;
350 struct grant_page *segments[MAX_INDIRECT_SEGMENTS];
351 /* Indirect descriptors */
352 struct grant_page *indirect_pages[MAX_INDIRECT_PAGES];
353 struct seg_buf seg[MAX_INDIRECT_SEGMENTS];
354 struct bio *biolist[MAX_INDIRECT_SEGMENTS];
355 struct gnttab_unmap_grant_ref unmap[MAX_INDIRECT_SEGMENTS];
356 struct page *unmap_pages[MAX_INDIRECT_SEGMENTS];
357 struct gntab_unmap_queue_data gnttab_unmap_data;
358 };
359
360
361 #define vbd_sz(_v) ((_v)->bdev->bd_part ? \
362 (_v)->bdev->bd_part->nr_sects : \
363 get_capacity((_v)->bdev->bd_disk))
364
365 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
366 #define xen_blkif_put(_b) \
367 do { \
368 if (atomic_dec_and_test(&(_b)->refcnt)) \
369 schedule_work(&(_b)->free_work);\
370 } while (0)
371
372 struct phys_req {
373 unsigned short dev;
374 blkif_sector_t nr_sects;
375 struct block_device *bdev;
376 blkif_sector_t sector_number;
377 };
378 int xen_blkif_interface_init(void);
379
380 int xen_blkif_xenbus_init(void);
381
382 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
383 int xen_blkif_schedule(void *arg);
384 int xen_blkif_purge_persistent(void *arg);
385 void xen_blkbk_free_caches(struct xen_blkif_ring *ring);
386
387 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
388 struct backend_info *be, int state);
389
390 int xen_blkbk_barrier(struct xenbus_transaction xbt,
391 struct backend_info *be, int state);
392 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
393 void xen_blkbk_unmap_purged_grants(struct work_struct *work);
394
blkif_get_x86_32_req(struct blkif_request * dst,struct blkif_x86_32_request * src)395 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
396 struct blkif_x86_32_request *src)
397 {
398 int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
399 dst->operation = READ_ONCE(src->operation);
400 switch (dst->operation) {
401 case BLKIF_OP_READ:
402 case BLKIF_OP_WRITE:
403 case BLKIF_OP_WRITE_BARRIER:
404 case BLKIF_OP_FLUSH_DISKCACHE:
405 dst->u.rw.nr_segments = src->u.rw.nr_segments;
406 dst->u.rw.handle = src->u.rw.handle;
407 dst->u.rw.id = src->u.rw.id;
408 dst->u.rw.sector_number = src->u.rw.sector_number;
409 barrier();
410 if (n > dst->u.rw.nr_segments)
411 n = dst->u.rw.nr_segments;
412 for (i = 0; i < n; i++)
413 dst->u.rw.seg[i] = src->u.rw.seg[i];
414 break;
415 case BLKIF_OP_DISCARD:
416 dst->u.discard.flag = src->u.discard.flag;
417 dst->u.discard.id = src->u.discard.id;
418 dst->u.discard.sector_number = src->u.discard.sector_number;
419 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
420 break;
421 case BLKIF_OP_INDIRECT:
422 dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
423 dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
424 dst->u.indirect.handle = src->u.indirect.handle;
425 dst->u.indirect.id = src->u.indirect.id;
426 dst->u.indirect.sector_number = src->u.indirect.sector_number;
427 barrier();
428 j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
429 for (i = 0; i < j; i++)
430 dst->u.indirect.indirect_grefs[i] =
431 src->u.indirect.indirect_grefs[i];
432 break;
433 default:
434 /*
435 * Don't know how to translate this op. Only get the
436 * ID so failure can be reported to the frontend.
437 */
438 dst->u.other.id = src->u.other.id;
439 break;
440 }
441 }
442
blkif_get_x86_64_req(struct blkif_request * dst,struct blkif_x86_64_request * src)443 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
444 struct blkif_x86_64_request *src)
445 {
446 int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
447 dst->operation = READ_ONCE(src->operation);
448 switch (dst->operation) {
449 case BLKIF_OP_READ:
450 case BLKIF_OP_WRITE:
451 case BLKIF_OP_WRITE_BARRIER:
452 case BLKIF_OP_FLUSH_DISKCACHE:
453 dst->u.rw.nr_segments = src->u.rw.nr_segments;
454 dst->u.rw.handle = src->u.rw.handle;
455 dst->u.rw.id = src->u.rw.id;
456 dst->u.rw.sector_number = src->u.rw.sector_number;
457 barrier();
458 if (n > dst->u.rw.nr_segments)
459 n = dst->u.rw.nr_segments;
460 for (i = 0; i < n; i++)
461 dst->u.rw.seg[i] = src->u.rw.seg[i];
462 break;
463 case BLKIF_OP_DISCARD:
464 dst->u.discard.flag = src->u.discard.flag;
465 dst->u.discard.id = src->u.discard.id;
466 dst->u.discard.sector_number = src->u.discard.sector_number;
467 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
468 break;
469 case BLKIF_OP_INDIRECT:
470 dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
471 dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
472 dst->u.indirect.handle = src->u.indirect.handle;
473 dst->u.indirect.id = src->u.indirect.id;
474 dst->u.indirect.sector_number = src->u.indirect.sector_number;
475 barrier();
476 j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
477 for (i = 0; i < j; i++)
478 dst->u.indirect.indirect_grefs[i] =
479 src->u.indirect.indirect_grefs[i];
480 break;
481 default:
482 /*
483 * Don't know how to translate this op. Only get the
484 * ID so failure can be reported to the frontend.
485 */
486 dst->u.other.id = src->u.other.id;
487 break;
488 }
489 }
490
491 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */
492
