2 * Copyright (c) 2018 Citrix Systems Inc.
3 * (c) Gerd Hoffmann <kraxel@redhat.com>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; under version 2 of the License.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, see <http://www.gnu.org/licenses/>.
17 * Contributions after 2012-01-13 are licensed under the terms of the
18 * GNU GPL, version 2 or (at your option) any later version.
21 #include "qemu/osdep.h"
22 #include "qemu/error-report.h"
23 #include "qapi/error.h"
25 #include "hw/xen/xen_common.h"
26 #include "hw/block/xen_blkif.h"
27 #include "sysemu/block-backend.h"
28 #include "sysemu/iothread.h"
29 #include "xen-block.h"
31 typedef struct XenBlockRequest
{
41 XenBlockDataPlane
*dataplane
;
42 QLIST_ENTRY(XenBlockRequest
) list
;
46 struct XenBlockDataPlane
{
48 XenEventChannel
*event_channel
;
49 unsigned int *ring_ref
;
50 unsigned int nr_ring_ref
;
54 blkif_back_rings_t rings
;
56 QLIST_HEAD(inflight_head
, XenBlockRequest
) inflight
;
57 QLIST_HEAD(freelist_head
, XenBlockRequest
) freelist
;
59 int requests_inflight
;
60 unsigned int max_requests
;
67 static void reset_request(XenBlockRequest
*request
)
69 memset(&request
->req
, 0, sizeof(request
->req
));
75 request
->aio_inflight
= 0;
76 request
->aio_errors
= 0;
78 request
->dataplane
= NULL
;
79 memset(&request
->list
, 0, sizeof(request
->list
));
80 memset(&request
->acct
, 0, sizeof(request
->acct
));
82 qemu_iovec_reset(&request
->v
);
85 static XenBlockRequest
*xen_block_start_request(XenBlockDataPlane
*dataplane
)
87 XenBlockRequest
*request
= NULL
;
89 if (QLIST_EMPTY(&dataplane
->freelist
)) {
90 if (dataplane
->requests_total
>= dataplane
->max_requests
) {
93 /* allocate new struct */
94 request
= g_malloc0(sizeof(*request
));
95 request
->dataplane
= dataplane
;
97 * We cannot need more pages per requests than this, and since we
98 * re-use requests, allocate the memory once here. It will be freed
99 * xen_block_dataplane_destroy() when the request list is freed.
101 request
->buf
= qemu_memalign(XC_PAGE_SIZE
,
102 BLKIF_MAX_SEGMENTS_PER_REQUEST
*
104 dataplane
->requests_total
++;
105 qemu_iovec_init(&request
->v
, 1);
107 /* get one from freelist */
108 request
= QLIST_FIRST(&dataplane
->freelist
);
109 QLIST_REMOVE(request
, list
);
111 QLIST_INSERT_HEAD(&dataplane
->inflight
, request
, list
);
112 dataplane
->requests_inflight
++;
118 static void xen_block_finish_request(XenBlockRequest
*request
)
120 XenBlockDataPlane
*dataplane
= request
->dataplane
;
122 QLIST_REMOVE(request
, list
);
123 dataplane
->requests_inflight
--;
126 static void xen_block_release_request(XenBlockRequest
*request
)
128 XenBlockDataPlane
*dataplane
= request
->dataplane
;
130 QLIST_REMOVE(request
, list
);
131 reset_request(request
);
132 request
->dataplane
= dataplane
;
133 QLIST_INSERT_HEAD(&dataplane
->freelist
, request
, list
);
134 dataplane
->requests_inflight
--;
138 * translate request into iovec + start offset
139 * do sanity checks along the way
141 static int xen_block_parse_request(XenBlockRequest
*request
)
143 XenBlockDataPlane
*dataplane
= request
->dataplane
;
147 switch (request
->req
.operation
) {
150 case BLKIF_OP_FLUSH_DISKCACHE
:
151 request
->presync
= 1;
152 if (!request
->req
.nr_segments
) {
158 case BLKIF_OP_DISCARD
:
161 error_report("error: unknown operation (%d)", request
->req
.operation
);
165 if (request
->req
.operation
!= BLKIF_OP_READ
&&
166 blk_is_read_only(dataplane
->blk
)) {
167 error_report("error: write req for ro device");
171 request
->start
= request
->req
.sector_number
* dataplane
->file_blk
;
172 for (i
= 0; i
< request
->req
.nr_segments
; i
++) {
173 if (i
== BLKIF_MAX_SEGMENTS_PER_REQUEST
) {
174 error_report("error: nr_segments too big");
177 if (request
->req
.seg
[i
].first_sect
> request
->req
.seg
[i
].last_sect
) {
178 error_report("error: first > last sector");
181 if (request
->req
.seg
[i
].last_sect
* dataplane
->file_blk
>=
183 error_report("error: page crossing");
187 len
= (request
->req
.seg
[i
].last_sect
-
188 request
->req
.seg
[i
].first_sect
+ 1) * dataplane
->file_blk
;
189 request
->size
+= len
;
191 if (request
->start
+ request
->size
> blk_getlength(dataplane
->blk
)) {
192 error_report("error: access beyond end of file");
198 request
->status
= BLKIF_RSP_ERROR
;
202 static int xen_block_copy_request(XenBlockRequest
*request
)
204 XenBlockDataPlane
*dataplane
= request
->dataplane
;
205 XenDevice
*xendev
= dataplane
->xendev
;
206 XenDeviceGrantCopySegment segs
[BLKIF_MAX_SEGMENTS_PER_REQUEST
];
208 int64_t file_blk
= dataplane
->file_blk
;
209 bool to_domain
= (request
->req
.operation
== BLKIF_OP_READ
);
210 void *virt
= request
->buf
;
211 Error
*local_err
= NULL
;
213 if (request
->req
.nr_segments
== 0) {
217 count
= request
->req
.nr_segments
;
219 for (i
= 0; i
< count
; i
++) {
221 segs
[i
].dest
.foreign
.ref
= request
->req
.seg
[i
].gref
;
222 segs
[i
].dest
.foreign
.offset
= request
->req
.seg
[i
].first_sect
*
224 segs
[i
].source
.virt
= virt
;
226 segs
[i
].source
.foreign
.ref
= request
->req
.seg
[i
].gref
;
227 segs
[i
].source
.foreign
.offset
= request
->req
.seg
[i
].first_sect
*
229 segs
[i
].dest
.virt
= virt
;
231 segs
[i
].len
= (request
->req
.seg
[i
].last_sect
-
232 request
->req
.seg
[i
].first_sect
+ 1) * file_blk
;
236 xen_device_copy_grant_refs(xendev
, to_domain
, segs
, count
, &local_err
);
239 error_reportf_err(local_err
, "failed to copy data: ");
241 request
->aio_errors
++;
248 static int xen_block_do_aio(XenBlockRequest
*request
);
249 static int xen_block_send_response(XenBlockRequest
*request
);
251 static void xen_block_complete_aio(void *opaque
, int ret
)
253 XenBlockRequest
*request
= opaque
;
254 XenBlockDataPlane
*dataplane
= request
->dataplane
;
256 aio_context_acquire(dataplane
->ctx
);
259 error_report("%s I/O error",
260 request
->req
.operation
== BLKIF_OP_READ
?
262 request
->aio_errors
++;
265 request
->aio_inflight
--;
266 if (request
->presync
) {
267 request
->presync
= 0;
268 xen_block_do_aio(request
);
271 if (request
->aio_inflight
> 0) {
275 switch (request
->req
.operation
) {
277 /* in case of failure request->aio_errors is increased */
279 xen_block_copy_request(request
);
283 case BLKIF_OP_FLUSH_DISKCACHE
:
284 if (!request
->req
.nr_segments
) {
292 request
->status
= request
->aio_errors
? BLKIF_RSP_ERROR
: BLKIF_RSP_OKAY
;
293 xen_block_finish_request(request
);
295 switch (request
->req
.operation
) {
297 case BLKIF_OP_FLUSH_DISKCACHE
:
298 if (!request
->req
.nr_segments
) {
302 if (request
->status
== BLKIF_RSP_OKAY
) {
303 block_acct_done(blk_get_stats(dataplane
->blk
), &request
->acct
);
305 block_acct_failed(blk_get_stats(dataplane
->blk
), &request
->acct
);
308 case BLKIF_OP_DISCARD
:
312 if (xen_block_send_response(request
)) {
313 Error
*local_err
= NULL
;
315 xen_device_notify_event_channel(dataplane
->xendev
,
316 dataplane
->event_channel
,
319 error_report_err(local_err
);
322 xen_block_release_request(request
);
324 qemu_bh_schedule(dataplane
->bh
);
327 aio_context_release(dataplane
->ctx
);
330 static bool xen_block_split_discard(XenBlockRequest
*request
,
331 blkif_sector_t sector_number
,
334 XenBlockDataPlane
*dataplane
= request
->dataplane
;
337 uint64_t byte_remaining
, limit
;
338 uint64_t sec_start
= sector_number
;
339 uint64_t sec_count
= nr_sectors
;
341 /* Wrap around, or overflowing byte limit? */
342 if (sec_start
+ sec_count
< sec_count
||
343 sec_start
+ sec_count
> INT64_MAX
/ dataplane
->file_blk
) {
347 limit
= BDRV_REQUEST_MAX_SECTORS
* dataplane
->file_blk
;
348 byte_offset
= sec_start
* dataplane
->file_blk
;
349 byte_remaining
= sec_count
* dataplane
->file_blk
;
352 byte_chunk
= byte_remaining
> limit
? limit
: byte_remaining
;
353 request
->aio_inflight
++;
354 blk_aio_pdiscard(dataplane
->blk
, byte_offset
, byte_chunk
,
355 xen_block_complete_aio
, request
);
356 byte_remaining
-= byte_chunk
;
357 byte_offset
+= byte_chunk
;
358 } while (byte_remaining
> 0);
363 static int xen_block_do_aio(XenBlockRequest
*request
)
365 XenBlockDataPlane
*dataplane
= request
->dataplane
;
367 if (request
->req
.nr_segments
&&
368 (request
->req
.operation
== BLKIF_OP_WRITE
||
369 request
->req
.operation
== BLKIF_OP_FLUSH_DISKCACHE
) &&
370 xen_block_copy_request(request
)) {
374 request
->aio_inflight
++;
375 if (request
->presync
) {
376 blk_aio_flush(request
->dataplane
->blk
, xen_block_complete_aio
,
381 switch (request
->req
.operation
) {
383 qemu_iovec_add(&request
->v
, request
->buf
, request
->size
);
384 block_acct_start(blk_get_stats(dataplane
->blk
), &request
->acct
,
385 request
->v
.size
, BLOCK_ACCT_READ
);
386 request
->aio_inflight
++;
387 blk_aio_preadv(dataplane
->blk
, request
->start
, &request
->v
, 0,
388 xen_block_complete_aio
, request
);
391 case BLKIF_OP_FLUSH_DISKCACHE
:
392 if (!request
->req
.nr_segments
) {
396 qemu_iovec_add(&request
->v
, request
->buf
, request
->size
);
397 block_acct_start(blk_get_stats(dataplane
->blk
), &request
->acct
,
399 request
->req
.operation
== BLKIF_OP_WRITE
?
400 BLOCK_ACCT_WRITE
: BLOCK_ACCT_FLUSH
);
401 request
->aio_inflight
++;
402 blk_aio_pwritev(dataplane
->blk
, request
->start
, &request
->v
, 0,
403 xen_block_complete_aio
, request
);
405 case BLKIF_OP_DISCARD
:
407 struct blkif_request_discard
*req
= (void *)&request
->req
;
408 if (!xen_block_split_discard(request
, req
->sector_number
,
415 /* unknown operation (shouldn't happen -- parse catches this) */
419 xen_block_complete_aio(request
, 0);
424 xen_block_finish_request(request
);
425 request
->status
= BLKIF_RSP_ERROR
;
429 static int xen_block_send_response(XenBlockRequest
*request
)
431 XenBlockDataPlane
*dataplane
= request
->dataplane
;
433 int have_requests
= 0;
434 blkif_response_t
*resp
;
436 /* Place on the response ring for the relevant domain. */
437 switch (dataplane
->protocol
) {
438 case BLKIF_PROTOCOL_NATIVE
:
439 resp
= (blkif_response_t
*)RING_GET_RESPONSE(
440 &dataplane
->rings
.native
,
441 dataplane
->rings
.native
.rsp_prod_pvt
);
443 case BLKIF_PROTOCOL_X86_32
:
444 resp
= (blkif_response_t
*)RING_GET_RESPONSE(
445 &dataplane
->rings
.x86_32_part
,
446 dataplane
->rings
.x86_32_part
.rsp_prod_pvt
);
448 case BLKIF_PROTOCOL_X86_64
:
449 resp
= (blkif_response_t
*)RING_GET_RESPONSE(
450 &dataplane
->rings
.x86_64_part
,
451 dataplane
->rings
.x86_64_part
.rsp_prod_pvt
);
457 resp
->id
= request
->req
.id
;
458 resp
->operation
= request
->req
.operation
;
459 resp
->status
= request
->status
;
461 dataplane
->rings
.common
.rsp_prod_pvt
++;
463 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&dataplane
->rings
.common
,
465 if (dataplane
->rings
.common
.rsp_prod_pvt
==
466 dataplane
->rings
.common
.req_cons
) {
468 * Tail check for pending requests. Allows frontend to avoid
469 * notifications if requests are already in flight (lower
470 * overheads and promotes batching).
472 RING_FINAL_CHECK_FOR_REQUESTS(&dataplane
->rings
.common
,
474 } else if (RING_HAS_UNCONSUMED_REQUESTS(&dataplane
->rings
.common
)) {
479 dataplane
->more_work
++;
484 static int xen_block_get_request(XenBlockDataPlane
*dataplane
,
485 XenBlockRequest
*request
, RING_IDX rc
)
487 switch (dataplane
->protocol
) {
488 case BLKIF_PROTOCOL_NATIVE
: {
489 blkif_request_t
*req
=
490 RING_GET_REQUEST(&dataplane
->rings
.native
, rc
);
492 memcpy(&request
->req
, req
, sizeof(request
->req
));
495 case BLKIF_PROTOCOL_X86_32
: {
496 blkif_x86_32_request_t
*req
=
497 RING_GET_REQUEST(&dataplane
->rings
.x86_32_part
, rc
);
499 blkif_get_x86_32_req(&request
->req
, req
);
502 case BLKIF_PROTOCOL_X86_64
: {
503 blkif_x86_64_request_t
*req
=
504 RING_GET_REQUEST(&dataplane
->rings
.x86_64_part
, rc
);
506 blkif_get_x86_64_req(&request
->req
, req
);
510 /* Prevent the compiler from accessing the on-ring fields instead. */
516 * Threshold of in-flight requests above which we will start using
517 * blk_io_plug()/blk_io_unplug() to batch requests.
519 #define IO_PLUG_THRESHOLD 1
521 static void xen_block_handle_requests(XenBlockDataPlane
*dataplane
)
524 XenBlockRequest
*request
;
525 int inflight_atstart
= dataplane
->requests_inflight
;
528 dataplane
->more_work
= 0;
530 rc
= dataplane
->rings
.common
.req_cons
;
531 rp
= dataplane
->rings
.common
.sring
->req_prod
;
532 xen_rmb(); /* Ensure we see queued requests up to 'rp'. */
535 * If there was more than IO_PLUG_THRESHOLD requests in flight
536 * when we got here, this is an indication that there the bottleneck
537 * is below us, so it's worth beginning to batch up I/O requests
538 * rather than submitting them immediately. The maximum number
539 * of requests we're willing to batch is the number already in
540 * flight, so it can grow up to max_requests when the bottleneck
543 if (inflight_atstart
> IO_PLUG_THRESHOLD
) {
544 blk_io_plug(dataplane
->blk
);
547 /* pull request from ring */
548 if (RING_REQUEST_CONS_OVERFLOW(&dataplane
->rings
.common
, rc
)) {
551 request
= xen_block_start_request(dataplane
);
552 if (request
== NULL
) {
553 dataplane
->more_work
++;
556 xen_block_get_request(dataplane
, request
, rc
);
557 dataplane
->rings
.common
.req_cons
= ++rc
;
560 if (xen_block_parse_request(request
) != 0) {
561 switch (request
->req
.operation
) {
563 block_acct_invalid(blk_get_stats(dataplane
->blk
),
567 block_acct_invalid(blk_get_stats(dataplane
->blk
),
570 case BLKIF_OP_FLUSH_DISKCACHE
:
571 block_acct_invalid(blk_get_stats(dataplane
->blk
),
577 if (xen_block_send_response(request
)) {
578 Error
*local_err
= NULL
;
580 xen_device_notify_event_channel(dataplane
->xendev
,
581 dataplane
->event_channel
,
584 error_report_err(local_err
);
587 xen_block_release_request(request
);
591 if (inflight_atstart
> IO_PLUG_THRESHOLD
&&
592 batched
>= inflight_atstart
) {
593 blk_io_unplug(dataplane
->blk
);
595 xen_block_do_aio(request
);
596 if (inflight_atstart
> IO_PLUG_THRESHOLD
) {
597 if (batched
>= inflight_atstart
) {
598 blk_io_plug(dataplane
->blk
);
605 if (inflight_atstart
> IO_PLUG_THRESHOLD
) {
606 blk_io_unplug(dataplane
->blk
);
609 if (dataplane
->more_work
&&
610 dataplane
->requests_inflight
< dataplane
->max_requests
) {
611 qemu_bh_schedule(dataplane
->bh
);
615 static void xen_block_dataplane_bh(void *opaque
)
617 XenBlockDataPlane
*dataplane
= opaque
;
619 aio_context_acquire(dataplane
->ctx
);
620 xen_block_handle_requests(dataplane
);
621 aio_context_release(dataplane
->ctx
);
624 static void xen_block_dataplane_event(void *opaque
)
626 XenBlockDataPlane
*dataplane
= opaque
;
628 qemu_bh_schedule(dataplane
->bh
);
631 XenBlockDataPlane
*xen_block_dataplane_create(XenDevice
*xendev
,
635 XenBlockDataPlane
*dataplane
= g_new0(XenBlockDataPlane
, 1);
637 dataplane
->xendev
= xendev
;
638 dataplane
->file_blk
= conf
->logical_block_size
;
639 dataplane
->blk
= conf
->blk
;
641 QLIST_INIT(&dataplane
->inflight
);
642 QLIST_INIT(&dataplane
->freelist
);
645 dataplane
->iothread
= iothread
;
646 object_ref(OBJECT(dataplane
->iothread
));
647 dataplane
->ctx
= iothread_get_aio_context(dataplane
->iothread
);
649 dataplane
->ctx
= qemu_get_aio_context();
651 dataplane
->bh
= aio_bh_new(dataplane
->ctx
, xen_block_dataplane_bh
,
657 void xen_block_dataplane_destroy(XenBlockDataPlane
*dataplane
)
659 XenBlockRequest
*request
;
665 while (!QLIST_EMPTY(&dataplane
->freelist
)) {
666 request
= QLIST_FIRST(&dataplane
->freelist
);
667 QLIST_REMOVE(request
, list
);
668 qemu_iovec_destroy(&request
->v
);
669 qemu_vfree(request
->buf
);
673 qemu_bh_delete(dataplane
->bh
);
674 if (dataplane
->iothread
) {
675 object_unref(OBJECT(dataplane
->iothread
));
681 void xen_block_dataplane_stop(XenBlockDataPlane
*dataplane
)
689 aio_context_acquire(dataplane
->ctx
);
690 blk_set_aio_context(dataplane
->blk
, qemu_get_aio_context());
691 aio_context_release(dataplane
->ctx
);
693 xendev
= dataplane
->xendev
;
695 if (dataplane
->event_channel
) {
696 Error
*local_err
= NULL
;
698 xen_device_unbind_event_channel(xendev
, dataplane
->event_channel
,
700 dataplane
->event_channel
= NULL
;
703 error_report_err(local_err
);
707 if (dataplane
->sring
) {
708 Error
*local_err
= NULL
;
710 xen_device_unmap_grant_refs(xendev
, dataplane
->sring
,
711 dataplane
->nr_ring_ref
, &local_err
);
712 dataplane
->sring
= NULL
;
715 error_report_err(local_err
);
719 g_free(dataplane
->ring_ref
);
720 dataplane
->ring_ref
= NULL
;
723 void xen_block_dataplane_start(XenBlockDataPlane
*dataplane
,
724 const unsigned int ring_ref
[],
725 unsigned int nr_ring_ref
,
726 unsigned int event_channel
,
727 unsigned int protocol
,
730 XenDevice
*xendev
= dataplane
->xendev
;
731 Error
*local_err
= NULL
;
732 unsigned int ring_size
;
735 dataplane
->nr_ring_ref
= nr_ring_ref
;
736 dataplane
->ring_ref
= g_new(unsigned int, nr_ring_ref
);
738 for (i
= 0; i
< nr_ring_ref
; i
++) {
739 dataplane
->ring_ref
[i
] = ring_ref
[i
];
742 dataplane
->protocol
= protocol
;
744 ring_size
= XC_PAGE_SIZE
* dataplane
->nr_ring_ref
;
745 switch (dataplane
->protocol
) {
746 case BLKIF_PROTOCOL_NATIVE
:
748 dataplane
->max_requests
= __CONST_RING_SIZE(blkif
, ring_size
);
751 case BLKIF_PROTOCOL_X86_32
:
753 dataplane
->max_requests
= __CONST_RING_SIZE(blkif_x86_32
, ring_size
);
756 case BLKIF_PROTOCOL_X86_64
:
758 dataplane
->max_requests
= __CONST_RING_SIZE(blkif_x86_64
, ring_size
);
762 error_setg(errp
, "unknown protocol %u", dataplane
->protocol
);
766 xen_device_set_max_grant_refs(xendev
, dataplane
->nr_ring_ref
,
769 error_propagate(errp
, local_err
);
773 dataplane
->sring
= xen_device_map_grant_refs(xendev
,
775 dataplane
->nr_ring_ref
,
776 PROT_READ
| PROT_WRITE
,
779 error_propagate(errp
, local_err
);
783 switch (dataplane
->protocol
) {
784 case BLKIF_PROTOCOL_NATIVE
:
786 blkif_sring_t
*sring_native
= dataplane
->sring
;
788 BACK_RING_INIT(&dataplane
->rings
.native
, sring_native
, ring_size
);
791 case BLKIF_PROTOCOL_X86_32
:
793 blkif_x86_32_sring_t
*sring_x86_32
= dataplane
->sring
;
795 BACK_RING_INIT(&dataplane
->rings
.x86_32_part
, sring_x86_32
,
799 case BLKIF_PROTOCOL_X86_64
:
801 blkif_x86_64_sring_t
*sring_x86_64
= dataplane
->sring
;
803 BACK_RING_INIT(&dataplane
->rings
.x86_64_part
, sring_x86_64
,
809 dataplane
->event_channel
=
810 xen_device_bind_event_channel(xendev
, event_channel
,
811 xen_block_dataplane_event
, dataplane
,
814 error_propagate(errp
, local_err
);
818 aio_context_acquire(dataplane
->ctx
);
819 blk_set_aio_context(dataplane
->blk
, dataplane
->ctx
);
820 aio_context_release(dataplane
->ctx
);
824 xen_block_dataplane_stop(dataplane
);