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virtio-blk: do not use vring in dataplane

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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-02-14 18:17:09 +01:00 committed by Michael S. Tsirkin
parent 2906cddfec
commit 03de2f5274
4 changed files with 19 additions and 146 deletions
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112
hw/block/dataplane/virtio-blk.c
View File

@ -18,8 +18,6 @@
#include "qemu/thread.h"
#include "qemu/error-report.h"
#include "hw/virtio/virtio-access.h"
#include "hw/virtio/dataplane/vring.h"
#include "hw/virtio/dataplane/vring-accessors.h"
#include "sysemu/block-backend.h"
#include "hw/virtio/virtio-blk.h"
#include "virtio-blk.h"
@ -35,7 +33,7 @@ struct VirtIOBlockDataPlane {
VirtIOBlkConf *conf;
VirtIODevice *vdev;
Vring vring; /* virtqueue vring */
VirtQueue *vq; /* virtqueue vring */
EventNotifier *guest_notifier; /* irq */
QEMUBH *bh; /* bh for guest notification */
@ -48,94 +46,26 @@ struct VirtIOBlockDataPlane {
*/
IOThread *iothread;
AioContext *ctx;
EventNotifier host_notifier; /* doorbell */
/* Operation blocker on BDS */
Error *blocker;
void (*saved_complete_request)(struct VirtIOBlockReq *req,
unsigned char status);
};
/* Raise an interrupt to signal guest, if necessary */
static void notify_guest(VirtIOBlockDataPlane *s)
void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s)
{
if (!vring_should_notify(s->vdev, &s->vring)) {
return;
}
event_notifier_set(s->guest_notifier);
qemu_bh_schedule(s->bh);
}
static void notify_guest_bh(void *opaque)
{
VirtIOBlockDataPlane *s = opaque;
notify_guest(s);
}
static void complete_request_vring(VirtIOBlockReq *req, unsigned char status)
{
VirtIOBlockDataPlane *s = req->dev->dataplane;
stb_p(&req->in->status, status);
vring_push(s->vdev, &req->dev->dataplane->vring, &req->elem, req->in_len);
/* Suppress notification to guest by BH and its scheduled
* flag because requests are completed as a batch after io
* plug & unplug is introduced, and the BH can still be
* executed in dataplane aio context even after it is
* stopped, so needn't worry about notification loss with BH.
*/
qemu_bh_schedule(s->bh);
}
static void handle_notify(EventNotifier *e)
{
VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
host_notifier);
VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
event_notifier_test_and_clear(&s->host_notifier);
blk_io_plug(s->conf->conf.blk);
for (;;) {
MultiReqBuffer mrb = {};
/* Disable guest->host notifies to avoid unnecessary vmexits */
vring_disable_notification(s->vdev, &s->vring);
for (;;) {
VirtIOBlockReq *req = vring_pop(s->vdev, &s->vring,
sizeof(VirtIOBlockReq));
if (req == NULL) {
break; /* no more requests */
}
virtio_blk_init_request(vblk, req);
trace_virtio_blk_data_plane_process_request(s, req->elem.out_num,
req->elem.in_num,
req->elem.index);
virtio_blk_handle_request(req, &mrb);
}
if (mrb.num_reqs) {
virtio_blk_submit_multireq(s->conf->conf.blk, &mrb);
}
if (likely(!vring_more_avail(s->vdev, &s->vring))) { /* vring emptied */
/* Re-enable guest->host notifies and stop processing the vring.
* But if the guest has snuck in more descriptors, keep processing.
*/
vring_enable_notification(s->vdev, &s->vring);
if (!vring_more_avail(s->vdev, &s->vring)) {
break;
}
} else { /* fatal error */
break;
}
if (!virtio_should_notify(s->vdev, s->vq)) {
return;
}
blk_io_unplug(s->conf->conf.blk);
event_notifier_set(s->guest_notifier);
}
static void data_plane_set_up_op_blockers(VirtIOBlockDataPlane *s)
@ -260,7 +190,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
VirtQueue *vq;
int r;
if (vblk->dataplane_started || s->starting) {
@ -268,11 +197,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
}
s->starting = true;
vq = virtio_get_queue(s->vdev, 0);
if (!vring_setup(&s->vring, s->vdev, 0)) {
goto fail_vring;
}
s->vq = virtio_get_queue(s->vdev, 0);
/* Set up guest notifier (irq) */
r = k->set_guest_notifiers(qbus->parent, 1, true);
@ -281,7 +206,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
"ensure -enable-kvm is set\n", r);
goto fail_guest_notifiers;
}
s->guest_notifier = virtio_queue_get_guest_notifier(vq);
s->guest_notifier = virtio_queue_get_guest_notifier(s->vq);
/* Set up virtqueue notify */
r = k->set_host_notifier(qbus->parent, 0, true);
@ -289,10 +214,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
goto fail_host_notifier;
}
s->host_notifier = *virtio_queue_get_host_notifier(vq);
s->saved_complete_request = vblk->complete_request;
vblk->complete_request = complete_request_vring;
s->starting = false;
vblk->dataplane_started = true;
@ -301,20 +222,17 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
blk_set_aio_context(s->conf->conf.blk, s->ctx);
/* Kick right away to begin processing requests already in vring */
event_notifier_set(virtio_queue_get_host_notifier(vq));
event_notifier_set(virtio_queue_get_host_notifier(s->vq));
/* Get this show started by hooking up our callbacks */
aio_context_acquire(s->ctx);
aio_set_event_notifier(s->ctx, &s->host_notifier, true,
handle_notify);
virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, true, true);
aio_context_release(s->ctx);
return;
fail_host_notifier:
k->set_guest_notifiers(qbus->parent, 1, false);
fail_guest_notifiers:
vring_teardown(&s->vring, s->vdev, 0);
fail_vring:
s->disabled = true;
s->starting = false;
vblk->dataplane_started = true;
@ -338,24 +256,18 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
return;
}
s->stopping = true;
vblk->complete_request = s->saved_complete_request;
trace_virtio_blk_data_plane_stop(s);
aio_context_acquire(s->ctx);
/* Stop notifications for new requests from guest */
aio_set_event_notifier(s->ctx, &s->host_notifier, true, NULL);
virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, false, false);
/* Drain and switch bs back to the QEMU main loop */
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
aio_context_release(s->ctx);
/* Sync vring state back to virtqueue so that non-dataplane request
* processing can continue when we disable the host notifier below.
*/
vring_teardown(&s->vring, s->vdev, 0);
k->set_host_notifier(qbus->parent, 0, false);
/* Clean up guest notifier (irq) */

1
hw/block/dataplane/virtio-blk.h
View File

@ -26,5 +26,6 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s);
#endif /* HW_DATAPLANE_VIRTIO_BLK_H */

49
hw/block/virtio-blk.c
View File

@ -21,7 +21,6 @@
#include "sysemu/blockdev.h"
#include "hw/virtio/virtio-blk.h"
#include "dataplane/virtio-blk.h"
#include "migration/migration.h"
#include "block/scsi.h"
#ifdef __linux__
# include <scsi/sg.h>
@ -45,8 +44,7 @@ void virtio_blk_free_request(VirtIOBlockReq *req)
}
}
static void virtio_blk_complete_request(VirtIOBlockReq *req,
unsigned char status)
static void virtio_blk_req_complete(VirtIOBlockReq *req, unsigned char status)
{
VirtIOBlock *s = req->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(s);
@ -55,12 +53,11 @@ static void virtio_blk_complete_request(VirtIOBlockReq *req,
stb_p(&req->in->status, status);
virtqueue_push(s->vq, &req->elem, req->in_len);
virtio_notify(vdev, s->vq);
}
static void virtio_blk_req_complete(VirtIOBlockReq *req, unsigned char status)
{
req->dev->complete_request(req, status);
if (s->dataplane) {
virtio_blk_data_plane_notify(s->dataplane);
} else {
virtio_notify(vdev, s->vq);
}
}
static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
@ -852,36 +849,6 @@ static const BlockDevOps virtio_block_ops = {
.resize_cb = virtio_blk_resize,
};
/* Disable dataplane thread during live migration since it does not
* update the dirty memory bitmap yet.
*/
static void virtio_blk_migration_state_changed(Notifier *notifier, void *data)
{
VirtIOBlock *s = container_of(notifier, VirtIOBlock,
migration_state_notifier);
MigrationState *mig = data;
Error *err = NULL;
if (migration_in_setup(mig)) {
if (!s->dataplane) {
return;
}
virtio_blk_data_plane_destroy(s->dataplane);
s->dataplane = NULL;
} else if (migration_has_finished(mig) ||
migration_has_failed(mig)) {
if (s->dataplane) {
return;
}
blk_drain_all(); /* complete in-flight non-dataplane requests */
virtio_blk_data_plane_create(VIRTIO_DEVICE(s), &s->conf,
&s->dataplane, &err);
if (err != NULL) {
error_report_err(err);
}
}
}
static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
@ -916,15 +883,12 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
s->sector_mask = (s->conf.conf.logical_block_size / BDRV_SECTOR_SIZE) - 1;
s->vq = virtio_add_queue(vdev, 128, virtio_blk_handle_output);
s->complete_request = virtio_blk_complete_request;
virtio_blk_data_plane_create(vdev, conf, &s->dataplane, &err);
if (err != NULL) {
error_propagate(errp, err);
virtio_cleanup(vdev);
return;
}
s->migration_state_notifier.notify = virtio_blk_migration_state_changed;
add_migration_state_change_notifier(&s->migration_state_notifier);
s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
register_savevm(dev, "virtio-blk", virtio_blk_id++, 2,
@ -940,7 +904,6 @@ static void virtio_blk_device_unrealize(DeviceState *dev, Error **errp)
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOBlock *s = VIRTIO_BLK(dev);
remove_migration_state_change_notifier(&s->migration_state_notifier);
virtio_blk_data_plane_destroy(s->dataplane);
s->dataplane = NULL;
qemu_del_vm_change_state_handler(s->change);

3
include/hw/virtio/virtio-blk.h
View File

@ -53,9 +53,6 @@ typedef struct VirtIOBlock {
unsigned short sector_mask;
bool original_wce;
VMChangeStateEntry *change;
/* Function to push to vq and notify guest */
void (*complete_request)(struct VirtIOBlockReq *req, unsigned char status);
Notifier migration_state_notifier;
bool dataplane_started;
struct VirtIOBlockDataPlane *dataplane;
} VirtIOBlock;