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Block layer patches

Browse source 
- virtio-blk: Multiqueue fixes and cleanups
 - blklogwrites: Fixes for write_zeroes and superblock update races
 - commit/stream: Allow users to request only format driver names in
   backing file format
 - monitor: only run coroutine commands in qemu_aio_context
 - Some iotest fixes
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Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging

Block layer patches

- virtio-blk: Multiqueue fixes and cleanups
- blklogwrites: Fixes for write_zeroes and superblock update races
- commit/stream: Allow users to request only format driver names in
  backing file format
- monitor: only run coroutine commands in qemu_aio_context
- Some iotest fixes

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# gpg:                issuer "kwolf@redhat.com"
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* tag 'for-upstream' of https://repo.or.cz/qemu/kevin:
  iotests/277: Use iotests.sock_dir for socket creation
  iotests/iothreads-stream: Use the right TimeoutError
  tests/unit: Bump test-replication timeout to 60 seconds
  iotests/264: Use iotests.sock_dir for socket creation
  block/blklogwrites: Protect mutable driver state with a mutex.
  virtio-blk: always set ioeventfd during startup
  virtio-blk: tolerate failure to set BlockBackend AioContext
  virtio-blk: restart s->rq reqs in vq AioContexts
  virtio-blk: rename dataplane to ioeventfd
  virtio-blk: rename dataplane create/destroy functions
  virtio-blk: move dataplane code into virtio-blk.c
  monitor: only run coroutine commands in qemu_aio_context
  iotests: port 141 to Python for reliable QMP testing
  iotests: add filter_qmp_generated_node_ids()
  stream: Allow users to request only format driver names in backing file format
  commit: Allow users to request only format driver names in backing file format
  string-output-visitor: Fix (pseudo) struct handling
  block/blklogwrites: Fix a bug when logging "write zeroes" operations.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2024-01-26 13:10:30 +00:00
commit b9c4a2018a
59 changed files with 1001 additions and 1007 deletions
Download patch file Download diff file Expand all files Collapse all files

1
hw/block/dataplane/meson.build
View file

@ -1,2 +1 @@
system_ss.add(when: 'CONFIG_VIRTIO_BLK', if_true: files('virtio-blk.c'))
specific_ss.add(when: 'CONFIG_XEN_BUS', if_true: files('xen-block.c'))

5
hw/block/dataplane/trace-events
View file

@ -1,5 +0,0 @@
# See docs/devel/tracing.rst for syntax documentation.
# virtio-blk.c
virtio_blk_data_plane_start(void *s) "dataplane %p"
virtio_blk_data_plane_stop(void *s) "dataplane %p"

1
hw/block/dataplane/trace.h
View file

@ -1 +0,0 @@
#include "trace/trace-hw_block_dataplane.h"

404
hw/block/dataplane/virtio-blk.c
View file

@ -1,404 +0,0 @@
/*
* Dedicated thread for virtio-blk I/O processing
*
* Copyright 2012 IBM, Corp.
* Copyright 2012 Red Hat, Inc. and/or its affiliates
*
* Authors:
* Stefan Hajnoczi <stefanha@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "trace.h"
#include "qemu/iov.h"
#include "qemu/main-loop.h"
#include "qemu/thread.h"
#include "qemu/error-report.h"
#include "hw/virtio/virtio-blk.h"
#include "virtio-blk.h"
#include "block/aio.h"
#include "hw/virtio/virtio-bus.h"
#include "qom/object_interfaces.h"
struct VirtIOBlockDataPlane {
bool starting;
bool stopping;
VirtIOBlkConf *conf;
VirtIODevice *vdev;
/*
* The AioContext for each virtqueue. The BlockDriverState will use the
* first element as its AioContext.
*/
AioContext **vq_aio_context;
};
/* Raise an interrupt to signal guest, if necessary */
void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq)
{
virtio_notify_irqfd(s->vdev, vq);
}
/* Generate vq:AioContext mappings from a validated iothread-vq-mapping list */
static void
apply_vq_mapping(IOThreadVirtQueueMappingList *iothread_vq_mapping_list,
AioContext **vq_aio_context, uint16_t num_queues)
{
IOThreadVirtQueueMappingList *node;
size_t num_iothreads = 0;
size_t cur_iothread = 0;
for (node = iothread_vq_mapping_list; node; node = node->next) {
num_iothreads++;
}
for (node = iothread_vq_mapping_list; node; node = node->next) {
IOThread *iothread = iothread_by_id(node->value->iothread);
AioContext *ctx = iothread_get_aio_context(iothread);
/* Released in virtio_blk_data_plane_destroy() */
object_ref(OBJECT(iothread));
if (node->value->vqs) {
uint16List *vq;
/* Explicit vq:IOThread assignment */
for (vq = node->value->vqs; vq; vq = vq->next) {
vq_aio_context[vq->value] = ctx;
}
} else {
/* Round-robin vq:IOThread assignment */
for (unsigned i = cur_iothread; i < num_queues;
i += num_iothreads) {
vq_aio_context[i] = ctx;
}
}
cur_iothread++;
}
}
/* Context: BQL held */
bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
VirtIOBlockDataPlane **dataplane,
Error **errp)
{
VirtIOBlockDataPlane *s;
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
*dataplane = NULL;
if (conf->iothread || conf->iothread_vq_mapping_list) {
if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
error_setg(errp,
"device is incompatible with iothread "
"(transport does not support notifiers)");
return false;
}
if (!virtio_device_ioeventfd_enabled(vdev)) {
error_setg(errp, "ioeventfd is required for iothread");
return false;
}
/* If dataplane is (re-)enabled while the guest is running there could
* be block jobs that can conflict.
*/
if (blk_op_is_blocked(conf->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
error_prepend(errp, "cannot start virtio-blk dataplane: ");
return false;
}
}
/* Don't try if transport does not support notifiers. */
if (!virtio_device_ioeventfd_enabled(vdev)) {
return false;
}
s = g_new0(VirtIOBlockDataPlane, 1);
s->vdev = vdev;
s->conf = conf;
s->vq_aio_context = g_new(AioContext *, conf->num_queues);
if (conf->iothread_vq_mapping_list) {
apply_vq_mapping(conf->iothread_vq_mapping_list, s->vq_aio_context,
conf->num_queues);
} else if (conf->iothread) {
AioContext *ctx = iothread_get_aio_context(conf->iothread);
for (unsigned i = 0; i < conf->num_queues; i++) {
s->vq_aio_context[i] = ctx;
}
/* Released in virtio_blk_data_plane_destroy() */
object_ref(OBJECT(conf->iothread));
} else {
AioContext *ctx = qemu_get_aio_context();
for (unsigned i = 0; i < conf->num_queues; i++) {
s->vq_aio_context[i] = ctx;
}
}
*dataplane = s;
return true;
}
/* Context: BQL held */
void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
{
VirtIOBlock *vblk;
VirtIOBlkConf *conf;
if (!s) {
return;
}
vblk = VIRTIO_BLK(s->vdev);
assert(!vblk->dataplane_started);
conf = s->conf;
if (conf->iothread_vq_mapping_list) {
IOThreadVirtQueueMappingList *node;
for (node = conf->iothread_vq_mapping_list; node; node = node->next) {
IOThread *iothread = iothread_by_id(node->value->iothread);
object_unref(OBJECT(iothread));
}
}
if (conf->iothread) {
object_unref(OBJECT(conf->iothread));
}
g_free(s->vq_aio_context);
g_free(s);
}
/* Context: BQL held */
int virtio_blk_data_plane_start(VirtIODevice *vdev)
{
VirtIOBlock *vblk = VIRTIO_BLK(vdev);
VirtIOBlockDataPlane *s = vblk->dataplane;
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vblk)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
unsigned i;
unsigned nvqs = s->conf->num_queues;
Error *local_err = NULL;
int r;
if (vblk->dataplane_started || s->starting) {
return 0;
}
s->starting = true;
/* Set up guest notifier (irq) */
r = k->set_guest_notifiers(qbus->parent, nvqs, true);
if (r != 0) {
error_report("virtio-blk failed to set guest notifier (%d), "
"ensure -accel kvm is set.", r);
goto fail_guest_notifiers;
}
/*
* Batch all the host notifiers in a single transaction to avoid
* quadratic time complexity in address_space_update_ioeventfds().
*/
memory_region_transaction_begin();
/* Set up virtqueue notify */
for (i = 0; i < nvqs; i++) {
r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, true);
if (r != 0) {
int j = i;
fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
while (i--) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
/*
* The transaction expects the ioeventfds to be open when it
* commits. Do it now, before the cleanup loop.
*/
memory_region_transaction_commit();
while (j--) {
virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), j);
}
goto fail_host_notifiers;
}
}
memory_region_transaction_commit();
trace_virtio_blk_data_plane_start(s);
r = blk_set_aio_context(s->conf->conf.blk, s->vq_aio_context[0],
&local_err);
if (r < 0) {
error_report_err(local_err);
goto fail_aio_context;
}
/*
* These fields must be visible to the IOThread when it processes the
* virtqueue, otherwise it will think dataplane has not started yet.
*
* Make sure ->dataplane_started is false when blk_set_aio_context() is
* called above so that draining does not cause the host notifier to be
* detached/attached prematurely.
*/
s->starting = false;
vblk->dataplane_started = true;
smp_wmb(); /* paired with aio_notify_accept() on the read side */
/* Get this show started by hooking up our callbacks */
if (!blk_in_drain(s->conf->conf.blk)) {
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(s->vdev, i);
AioContext *ctx = s->vq_aio_context[i];
/* Kick right away to begin processing requests already in vring */
event_notifier_set(virtio_queue_get_host_notifier(vq));
virtio_queue_aio_attach_host_notifier(vq, ctx);
}
}
return 0;
fail_aio_context:
memory_region_transaction_begin();
for (i = 0; i < nvqs; i++) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
memory_region_transaction_commit();
for (i = 0; i < nvqs; i++) {
virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
}
fail_host_notifiers:
k->set_guest_notifiers(qbus->parent, nvqs, false);
fail_guest_notifiers:
vblk->dataplane_disabled = true;
s->starting = false;
return -ENOSYS;
}
/* Stop notifications for new requests from guest.
*
* Context: BH in IOThread
*/
static void virtio_blk_data_plane_stop_vq_bh(void *opaque)
{
VirtQueue *vq = opaque;
EventNotifier *host_notifier = virtio_queue_get_host_notifier(vq);
virtio_queue_aio_detach_host_notifier(vq, qemu_get_current_aio_context());
/*
* Test and clear notifier after disabling event, in case poll callback
* didn't have time to run.
*/
virtio_queue_host_notifier_read(host_notifier);
}
/* Context: BQL held */
void virtio_blk_data_plane_stop(VirtIODevice *vdev)
{
VirtIOBlock *vblk = VIRTIO_BLK(vdev);
VirtIOBlockDataPlane *s = vblk->dataplane;
BusState *qbus = qdev_get_parent_bus(DEVICE(vblk));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
unsigned i;
unsigned nvqs = s->conf->num_queues;
if (!vblk->dataplane_started || s->stopping) {
return;
}
/* Better luck next time. */
if (vblk->dataplane_disabled) {
vblk->dataplane_disabled = false;
vblk->dataplane_started = false;
return;
}
s->stopping = true;
trace_virtio_blk_data_plane_stop(s);
if (!blk_in_drain(s->conf->conf.blk)) {
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(s->vdev, i);
AioContext *ctx = s->vq_aio_context[i];
aio_wait_bh_oneshot(ctx, virtio_blk_data_plane_stop_vq_bh, vq);
}
}
/*
* Batch all the host notifiers in a single transaction to avoid
* quadratic time complexity in address_space_update_ioeventfds().
*/
memory_region_transaction_begin();
for (i = 0; i < nvqs; i++) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
/*
* The transaction expects the ioeventfds to be open when it
* commits. Do it now, before the cleanup loop.
*/
memory_region_transaction_commit();
for (i = 0; i < nvqs; i++) {
virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
}
/*
* Set ->dataplane_started to false before draining so that host notifiers
* are not detached/attached anymore.
*/
vblk->dataplane_started = false;
/* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
blk_drain(s->conf->conf.blk);
/*
* Try to switch bs back to the QEMU main loop. If other users keep the
* BlockBackend in the iothread, that's ok
*/
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL);
/* Clean up guest notifier (irq) */
k->set_guest_notifiers(qbus->parent, nvqs, false);
s->stopping = false;
}
void virtio_blk_data_plane_detach(VirtIOBlockDataPlane *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s->vdev);
for (uint16_t i = 0; i < s->conf->num_queues; i++) {
VirtQueue *vq = virtio_get_queue(vdev, i);
virtio_queue_aio_detach_host_notifier(vq, s->vq_aio_context[i]);
}
}
void virtio_blk_data_plane_attach(VirtIOBlockDataPlane *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s->vdev);
for (uint16_t i = 0; i < s->conf->num_queues; i++) {
VirtQueue *vq = virtio_get_queue(vdev, i);
virtio_queue_aio_attach_host_notifier(vq, s->vq_aio_context[i]);
}
}

34
hw/block/dataplane/virtio-blk.h
View file

@ -1,34 +0,0 @@
/*
* Dedicated thread for virtio-blk I/O processing
*
* Copyright 2012 IBM, Corp.
* Copyright 2012 Red Hat, Inc. and/or its affiliates
*
* Authors:
* Stefan Hajnoczi <stefanha@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#ifndef HW_DATAPLANE_VIRTIO_BLK_H
#define HW_DATAPLANE_VIRTIO_BLK_H
#include "hw/virtio/virtio.h"
typedef struct VirtIOBlockDataPlane VirtIOBlockDataPlane;
bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
VirtIOBlockDataPlane **dataplane,
Error **errp);
void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq);
int virtio_blk_data_plane_start(VirtIODevice *vdev);
void virtio_blk_data_plane_stop(VirtIODevice *vdev);
void virtio_blk_data_plane_detach(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_attach(VirtIOBlockDataPlane *s);
#endif /* HW_DATAPLANE_VIRTIO_BLK_H */

412
hw/block/virtio-blk.c
View file

@ -27,7 +27,6 @@
#include "sysemu/sysemu.h"
#include "sysemu/runstate.h"
#include "hw/virtio/virtio-blk.h"
#include "dataplane/virtio-blk.h"
#include "scsi/constants.h"
#ifdef __linux__
# include <scsi/sg.h>
@ -65,8 +64,8 @@ static void virtio_blk_req_complete(VirtIOBlockReq *req, unsigned char status)
iov_discard_undo(&req->inhdr_undo);
iov_discard_undo(&req->outhdr_undo);
virtqueue_push(req->vq, &req->elem, req->in_len);
if (s->dataplane_started && !s->dataplane_disabled) {
virtio_blk_data_plane_notify(s->dataplane, req->vq);
if (s->ioeventfd_started && !s->ioeventfd_disabled) {
virtio_notify_irqfd(vdev, req->vq);
} else {
virtio_notify(vdev, req->vq);
}
@ -1142,12 +1141,12 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBlock *s = (VirtIOBlock *)vdev;
if (s->dataplane && !s->dataplane_started) {
if (!s->ioeventfd_disabled && !s->ioeventfd_started) {
/* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
* dataplane here instead of waiting for .set_status().
* ioeventfd here instead of waiting for .set_status().
*/
virtio_device_start_ioeventfd(vdev);
if (!s->dataplane_disabled) {
if (!s->ioeventfd_disabled) {
return;
}
}
@ -1157,16 +1156,11 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
static void virtio_blk_dma_restart_bh(void *opaque)
{
VirtIOBlock *s = opaque;
VirtIOBlockReq *req = opaque;
VirtIOBlock *s = req->dev; /* we're called with at least one request */
VirtIOBlockReq *req;
MultiReqBuffer mrb = {};
WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
req = s->rq;
s->rq = NULL;
}
while (req) {
VirtIOBlockReq *next = req->next;
if (virtio_blk_handle_request(req, &mrb)) {
@ -1196,16 +1190,43 @@ static void virtio_blk_dma_restart_cb(void *opaque, bool running,
RunState state)
{
VirtIOBlock *s = opaque;
uint16_t num_queues = s->conf.num_queues;
if (!running) {
return;
}
/* Paired with dec in virtio_blk_dma_restart_bh() */
blk_inc_in_flight(s->conf.conf.blk);
/* Split the device-wide s->rq request list into per-vq request lists */
g_autofree VirtIOBlockReq **vq_rq = g_new0(VirtIOBlockReq *, num_queues);
VirtIOBlockReq *rq;
aio_bh_schedule_oneshot(blk_get_aio_context(s->conf.conf.blk),
virtio_blk_dma_restart_bh, s);
WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
rq = s->rq;
s->rq = NULL;
}
while (rq) {
VirtIOBlockReq *next = rq->next;
uint16_t idx = virtio_get_queue_index(rq->vq);
rq->next = vq_rq[idx];
vq_rq[idx] = rq;
rq = next;
}
/* Schedule a BH to submit the requests in each vq's AioContext */
for (uint16_t i = 0; i < num_queues; i++) {
if (!vq_rq[i]) {
continue;
}
/* Paired with dec in virtio_blk_dma_restart_bh() */
blk_inc_in_flight(s->conf.conf.blk);
aio_bh_schedule_oneshot(s->vq_aio_context[i],
virtio_blk_dma_restart_bh,
vq_rq[i]);
}
}
static void virtio_blk_reset(VirtIODevice *vdev)
@ -1214,7 +1235,7 @@ static void virtio_blk_reset(VirtIODevice *vdev)
VirtIOBlockReq *req;
/* Dataplane has stopped... */
assert(!s->dataplane_started);
assert(!s->ioeventfd_started);
/* ...but requests may still be in flight. */
blk_drain(s->blk);
@ -1381,7 +1402,7 @@ static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
VirtIOBlock *s = VIRTIO_BLK(vdev);
if (!(status & (VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK))) {
assert(!s->dataplane_started);
assert(!s->ioeventfd_started);
}
if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
@ -1546,16 +1567,34 @@ static void virtio_blk_resize(void *opaque)
aio_bh_schedule_oneshot(qemu_get_aio_context(), virtio_resize_cb, vdev);
}
static void virtio_blk_ioeventfd_detach(VirtIOBlock *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
for (uint16_t i = 0; i < s->conf.num_queues; i++) {
VirtQueue *vq = virtio_get_queue(vdev, i);
virtio_queue_aio_detach_host_notifier(vq, s->vq_aio_context[i]);
}
}
static void virtio_blk_ioeventfd_attach(VirtIOBlock *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
for (uint16_t i = 0; i < s->conf.num_queues; i++) {
VirtQueue *vq = virtio_get_queue(vdev, i);
virtio_queue_aio_attach_host_notifier(vq, s->vq_aio_context[i]);
}
}
/* Suspend virtqueue ioeventfd processing during drain */
static void virtio_blk_drained_begin(void *opaque)
{
VirtIOBlock *s = opaque;
if (!s->dataplane || !s->dataplane_started) {
return;
if (s->ioeventfd_started) {
virtio_blk_ioeventfd_detach(s);
}
virtio_blk_data_plane_detach(s->dataplane);
}
/* Resume virtqueue ioeventfd processing after drain */
@ -1563,11 +1602,9 @@ static void virtio_blk_drained_end(void *opaque)
{
VirtIOBlock *s = opaque;
if (!s->dataplane || !s->dataplane_started) {
return;
if (s->ioeventfd_started) {
virtio_blk_ioeventfd_attach(s);
}
virtio_blk_data_plane_attach(s->dataplane);
}
static const BlockDevOps virtio_block_ops = {
@ -1576,6 +1613,312 @@ static const BlockDevOps virtio_block_ops = {
.drained_end = virtio_blk_drained_end,
};
/* Generate vq:AioContext mappings from a validated iothread-vq-mapping list */
static void
apply_vq_mapping(IOThreadVirtQueueMappingList *iothread_vq_mapping_list,
AioContext **vq_aio_context, uint16_t num_queues)
{
IOThreadVirtQueueMappingList *node;
size_t num_iothreads = 0;
size_t cur_iothread = 0;
for (node = iothread_vq_mapping_list; node; node = node->next) {
num_iothreads++;
}
for (node = iothread_vq_mapping_list; node; node = node->next) {
IOThread *iothread = iothread_by_id(node->value->iothread);
AioContext *ctx = iothread_get_aio_context(iothread);
/* Released in virtio_blk_vq_aio_context_cleanup() */
object_ref(OBJECT(iothread));
if (node->value->vqs) {
uint16List *vq;
/* Explicit vq:IOThread assignment */
for (vq = node->value->vqs; vq; vq = vq->next) {
vq_aio_context[vq->value] = ctx;
}
} else {
/* Round-robin vq:IOThread assignment */
for (unsigned i = cur_iothread; i < num_queues;
i += num_iothreads) {
vq_aio_context[i] = ctx;
}
}
cur_iothread++;
}
}
/* Context: BQL held */
static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
VirtIOBlkConf *conf = &s->conf;
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
if (conf->iothread || conf->iothread_vq_mapping_list) {
if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
error_setg(errp,
"device is incompatible with iothread "
"(transport does not support notifiers)");
return false;
}
if (!virtio_device_ioeventfd_enabled(vdev)) {
error_setg(errp, "ioeventfd is required for iothread");
return false;
}
/*
* If ioeventfd is (re-)enabled while the guest is running there could
* be block jobs that can conflict.
*/
if (blk_op_is_blocked(conf->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
error_prepend(errp, "cannot start virtio-blk ioeventfd: ");
return false;
}
}
s->vq_aio_context = g_new(AioContext *, conf->num_queues);
if (conf->iothread_vq_mapping_list) {
apply_vq_mapping(conf->iothread_vq_mapping_list, s->vq_aio_context,
conf->num_queues);
} else if (conf->iothread) {
AioContext *ctx = iothread_get_aio_context(conf->iothread);
for (unsigned i = 0; i < conf->num_queues; i++) {
s->vq_aio_context[i] = ctx;
}
/* Released in virtio_blk_vq_aio_context_cleanup() */
object_ref(OBJECT(conf->iothread));
} else {
AioContext *ctx = qemu_get_aio_context();
for (unsigned i = 0; i < conf->num_queues; i++) {
s->vq_aio_context[i] = ctx;
}
}
return true;
}
/* Context: BQL held */
static void virtio_blk_vq_aio_context_cleanup(VirtIOBlock *s)
{
VirtIOBlkConf *conf = &s->conf;
assert(!s->ioeventfd_started);
if (conf->iothread_vq_mapping_list) {
IOThreadVirtQueueMappingList *node;
for (node = conf->iothread_vq_mapping_list; node; node = node->next) {
IOThread *iothread = iothread_by_id(node->value->iothread);
object_unref(OBJECT(iothread));
}
}
if (conf->iothread) {
object_unref(OBJECT(conf->iothread));
}
g_free(s->vq_aio_context);
s->vq_aio_context = NULL;
}
/* Context: BQL held */
static int virtio_blk_start_ioeventfd(VirtIODevice *vdev)
{
VirtIOBlock *s = VIRTIO_BLK(vdev);
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
unsigned i;
unsigned nvqs = s->conf.num_queues;
Error *local_err = NULL;
int r;
if (s->ioeventfd_started || s->ioeventfd_starting) {
return 0;
}
s->ioeventfd_starting = true;
/* Set up guest notifier (irq) */
r = k->set_guest_notifiers(qbus->parent, nvqs, true);
if (r != 0) {
error_report("virtio-blk failed to set guest notifier (%d), "
"ensure -accel kvm is set.", r);
goto fail_guest_notifiers;
}
/*
* Batch all the host notifiers in a single transaction to avoid
* quadratic time complexity in address_space_update_ioeventfds().
*/
memory_region_transaction_begin();
/* Set up virtqueue notify */
for (i = 0; i < nvqs; i++) {
r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, true);
if (r != 0) {
int j = i;
fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
while (i--) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
/*
* The transaction expects the ioeventfds to be open when it
* commits. Do it now, before the cleanup loop.
*/
memory_region_transaction_commit();
while (j--) {
virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), j);
}
goto fail_host_notifiers;
}
}
memory_region_transaction_commit();
/*
* Try to change the AioContext so that block jobs and other operations can
* co-locate their activity in the same AioContext. If it fails, nevermind.
*/
r = blk_set_aio_context(s->conf.conf.blk, s->vq_aio_context[0],
&local_err);
if (r < 0) {
warn_report_err(local_err);
}
/*
* These fields must be visible to the IOThread when it processes the
* virtqueue, otherwise it will think ioeventfd has not started yet.
*
* Make sure ->ioeventfd_started is false when blk_set_aio_context() is
* called above so that draining does not cause the host notifier to be
* detached/attached prematurely.
*/
s->ioeventfd_starting = false;
s->ioeventfd_started = true;
smp_wmb(); /* paired with aio_notify_accept() on the read side */
/* Get this show started by hooking up our callbacks */
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(vdev, i);
AioContext *ctx = s->vq_aio_context[i];
/* Kick right away to begin processing requests already in vring */
event_notifier_set(virtio_queue_get_host_notifier(vq));
if (!blk_in_drain(s->conf.conf.blk)) {
virtio_queue_aio_attach_host_notifier(vq, ctx);
}
}
return 0;
fail_host_notifiers:
k->set_guest_notifiers(qbus->parent, nvqs, false);
fail_guest_notifiers:
s->ioeventfd_disabled = true;
s->ioeventfd_starting = false;
return -ENOSYS;
}
/* Stop notifications for new requests from guest.
*
* Context: BH in IOThread
*/
static void virtio_blk_ioeventfd_stop_vq_bh(void *opaque)
{
VirtQueue *vq = opaque;
EventNotifier *host_notifier = virtio_queue_get_host_notifier(vq);
virtio_queue_aio_detach_host_notifier(vq, qemu_get_current_aio_context());
/*
* Test and clear notifier after disabling event, in case poll callback
* didn't have time to run.
*/
virtio_queue_host_notifier_read(host_notifier);
}
/* Context: BQL held */
static void virtio_blk_stop_ioeventfd(VirtIODevice *vdev)
{
VirtIOBlock *s = VIRTIO_BLK(vdev);
BusState *qbus = qdev_get_parent_bus(DEVICE(s));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
unsigned i;
unsigned nvqs = s->conf.num_queues;
if (!s->ioeventfd_started || s->ioeventfd_stopping) {
return;
}
/* Better luck next time. */
if (s->ioeventfd_disabled) {
s->ioeventfd_disabled = false;
s->ioeventfd_started = false;
return;
}
s->ioeventfd_stopping = true;
if (!blk_in_drain(s->conf.conf.blk)) {
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(vdev, i);
AioContext *ctx = s->vq_aio_context[i];
aio_wait_bh_oneshot(ctx, virtio_blk_ioeventfd_stop_vq_bh, vq);
}
}
/*
* Batch all the host notifiers in a single transaction to avoid
* quadratic time complexity in address_space_update_ioeventfds().
*/
memory_region_transaction_begin();
for (i = 0; i < nvqs; i++) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
/*
* The transaction expects the ioeventfds to be open when it
* commits. Do it now, before the cleanup loop.
*/
memory_region_transaction_commit();
for (i = 0; i < nvqs; i++) {
virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
}
/*
* Set ->ioeventfd_started to false before draining so that host notifiers
* are not detached/attached anymore.
*/
s->ioeventfd_started = false;
/* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
blk_drain(s->conf.conf.blk);
/*
* Try to switch bs back to the QEMU main loop. If other users keep the
* BlockBackend in the iothread, that's ok
*/
blk_set_aio_context(s->conf.conf.blk, qemu_get_aio_context(), NULL);
/* Clean up guest notifier (irq) */
k->set_guest_notifiers(qbus->parent, nvqs, false);
s->ioeventfd_stopping = false;
}
static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
@ -1680,7 +2023,13 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
virtio_add_queue(vdev, conf->queue_size, virtio_blk_handle_output);
}
qemu_coroutine_inc_pool_size(conf->num_queues * conf->queue_size / 2);
virtio_blk_data_plane_create(vdev, conf, &s->dataplane, &err);
/* Don't start ioeventfd if transport does not support notifiers. */
if (!virtio_device_ioeventfd_enabled(vdev)) {
s->ioeventfd_disabled = true;
}
virtio_blk_vq_aio_context_init(s, &err);
if (err != NULL) {
error_propagate(errp, err);
for (i = 0; i < conf->num_queues; i++) {
@ -1717,8 +2066,7 @@ static void virtio_blk_device_unrealize(DeviceState *dev)
blk_drain(s->blk);
del_boot_device_lchs(dev, "/disk@0,0");
virtio_blk_data_plane_destroy(s->dataplane);
s->dataplane = NULL;
virtio_blk_vq_aio_context_cleanup(s);
for (i = 0; i < conf->num_queues; i++) {
virtio_del_queue(vdev, i);
}
@ -1802,8 +2150,8 @@ static void virtio_blk_class_init(ObjectClass *klass, void *data)
vdc->reset = virtio_blk_reset;
vdc->save = virtio_blk_save_device;
vdc->load = virtio_blk_load_device;
vdc->start_ioeventfd = virtio_blk_data_plane_start;
vdc->stop_ioeventfd = virtio_blk_data_plane_stop;
vdc->start_ioeventfd = virtio_blk_start_ioeventfd;
vdc->stop_ioeventfd = virtio_blk_stop_ioeventfd;
}
static const TypeInfo virtio_blk_info = {