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[Qemu-block] [PATCH 14/40] virtio-blk: do not use vring in dataplane
From: |
Paolo Bonzini |
Subject: |
[Qemu-block] [PATCH 14/40] virtio-blk: do not use vring in dataplane |
Date: |
Tue, 24 Nov 2015 19:01:05 +0100 |
Signed-off-by: Paolo Bonzini <address@hidden>
---
hw/block/dataplane/virtio-blk.c | 112 +++++-----------------------------------
hw/block/dataplane/virtio-blk.h | 1 +
hw/block/virtio-blk.c | 48 +++--------------
include/hw/virtio/virtio-blk.h | 3 --
4 files changed, 19 insertions(+), 145 deletions(-)
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 8d417e2..f2482eb 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -17,8 +17,6 @@
#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"
@@ -34,7 +32,7 @@ struct VirtIOBlockDataPlane {
VirtIOBlkConf *conf;
VirtIODevice *vdev;
- Vring vring; /* virtqueue vring */
+ VirtQueue *vq; /* virtqueue vring */
EventNotifier *guest_notifier; /* irq */
QEMUBH *bh; /* bh for guest notification */
@@ -46,94 +44,26 @@ struct VirtIOBlockDataPlane {
IOThread *iothread;
IOThread internal_iothread_obj;
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);
}
/* Context: QEMU global mutex held */
@@ -233,7 +163,6 @@ 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) {
@@ -241,11 +170,7 @@ 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);
@@ -254,7 +179,7 @@ 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);
@@ -262,10 +187,6 @@ 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;
@@ -274,20 +195,17 @@ 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;
@@ -311,24 +229,18 @@ 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) */
diff --git a/hw/block/dataplane/virtio-blk.h b/hw/block/dataplane/virtio-blk.h
index c88d40e..0714c11 100644
--- a/hw/block/dataplane/virtio-blk.h
+++ b/hw/block/dataplane/virtio-blk.h
@@ -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 */
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 062d57e..e83d823 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -44,8 +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);
@@ -54,12 +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,
@@ -859,36 +857,6 @@ 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);
@@ -923,15 +891,12 @@ 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,
@@ -947,7 +912,6 @@ 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);
diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index e720934..4c72021 100644
--- a/include/hw/virtio/virtio-blk.h
+++ b/include/hw/virtio/virtio-blk.h
@@ -54,9 +54,6 @@ 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;
--
1.8.3.1
- [Qemu-block] [PATCH 03/40] virtio: move allocation to virtqueue_pop/vring_pop, (continued)
- [Qemu-block] [PATCH 03/40] virtio: move allocation to virtqueue_pop/vring_pop, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 06/40] virtio: introduce virtqueue_alloc_element, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 04/40] virtio: introduce qemu_get/put_virtqueue_element, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 07/40] virtio: slim down allocation of VirtQueueElements, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 09/40] vring: make vring_enable_notification return void, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 08/40] vring: slim down allocation of VirtQueueElements, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 05/40] virtio: read/write the VirtQueueElement a field at a time, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 10/40] virtio: combine the read of a descriptor, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 12/40] virtio: export vring_notify as virtio_should_notify, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 13/40] virtio-blk: fix "disabled data plane" mode, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 14/40] virtio-blk: do not use vring in dataplane,
Paolo Bonzini <=
- [Qemu-block] [PATCH 11/40] virtio: add AioContext-specific function for host notifiers, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 15/40] virtio-scsi: do not use vring in dataplane, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 16/40] vring: remove, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 18/40] qemu-thread: introduce QemuRecMutex, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 17/40] iothread: release AioContext around aio_poll, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 20/40] aio: rename bh_lock to list_lock, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 19/40] aio: convert from RFifoLock to QemuRecMutex, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 22/40] aio: make ctx->list_lock a QemuLockCnt, subsuming ctx->walking_bh, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 21/40] qemu-thread: introduce QemuLockCnt, Paolo Bonzini, 2015/11/24
- [Qemu-block] [PATCH 23/40] qemu-thread: optimize QemuLockCnt with futexes on Linux, Paolo Bonzini, 2015/11/24