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virtio-blk: do not use vring in dataplane
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
Michael S. Tsirkin
parent
2906cddfec
commit
03de2f5274
4 changed files with 19 additions and 146 deletions
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@ -18,8 +18,6 @@
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#include "qemu/thread.h"
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#include "qemu/error-report.h"
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#include "hw/virtio/virtio-access.h"
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#include "hw/virtio/dataplane/vring.h"
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#include "hw/virtio/dataplane/vring-accessors.h"
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#include "sysemu/block-backend.h"
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#include "hw/virtio/virtio-blk.h"
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#include "virtio-blk.h"
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@ -35,7 +33,7 @@ struct VirtIOBlockDataPlane {
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VirtIOBlkConf *conf;
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VirtIODevice *vdev;
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Vring vring; /* virtqueue vring */
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VirtQueue *vq; /* virtqueue vring */
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EventNotifier *guest_notifier; /* irq */
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QEMUBH *bh; /* bh for guest notification */
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@ -48,94 +46,26 @@ struct VirtIOBlockDataPlane {
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*/
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IOThread *iothread;
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AioContext *ctx;
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EventNotifier host_notifier; /* doorbell */
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/* Operation blocker on BDS */
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Error *blocker;
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void (*saved_complete_request)(struct VirtIOBlockReq *req,
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unsigned char status);
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};
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/* Raise an interrupt to signal guest, if necessary */
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static void notify_guest(VirtIOBlockDataPlane *s)
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void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s)
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{
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if (!vring_should_notify(s->vdev, &s->vring)) {
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return;
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}
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event_notifier_set(s->guest_notifier);
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qemu_bh_schedule(s->bh);
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}
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static void notify_guest_bh(void *opaque)
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{
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VirtIOBlockDataPlane *s = opaque;
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notify_guest(s);
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}
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static void complete_request_vring(VirtIOBlockReq *req, unsigned char status)
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{
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VirtIOBlockDataPlane *s = req->dev->dataplane;
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stb_p(&req->in->status, status);
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vring_push(s->vdev, &req->dev->dataplane->vring, &req->elem, req->in_len);
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/* Suppress notification to guest by BH and its scheduled
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* flag because requests are completed as a batch after io
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* plug & unplug is introduced, and the BH can still be
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* executed in dataplane aio context even after it is
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* stopped, so needn't worry about notification loss with BH.
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*/
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qemu_bh_schedule(s->bh);
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}
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static void handle_notify(EventNotifier *e)
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{
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VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
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host_notifier);
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VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
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event_notifier_test_and_clear(&s->host_notifier);
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blk_io_plug(s->conf->conf.blk);
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for (;;) {
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MultiReqBuffer mrb = {};
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/* Disable guest->host notifies to avoid unnecessary vmexits */
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vring_disable_notification(s->vdev, &s->vring);
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for (;;) {
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VirtIOBlockReq *req = vring_pop(s->vdev, &s->vring,
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sizeof(VirtIOBlockReq));
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if (req == NULL) {
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break; /* no more requests */
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}
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virtio_blk_init_request(vblk, req);
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trace_virtio_blk_data_plane_process_request(s, req->elem.out_num,
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req->elem.in_num,
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req->elem.index);
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virtio_blk_handle_request(req, &mrb);
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}
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if (mrb.num_reqs) {
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virtio_blk_submit_multireq(s->conf->conf.blk, &mrb);
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}
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if (likely(!vring_more_avail(s->vdev, &s->vring))) { /* vring emptied */
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/* Re-enable guest->host notifies and stop processing the vring.
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* But if the guest has snuck in more descriptors, keep processing.
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*/
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vring_enable_notification(s->vdev, &s->vring);
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if (!vring_more_avail(s->vdev, &s->vring)) {
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break;
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}
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} else { /* fatal error */
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break;
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}
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if (!virtio_should_notify(s->vdev, s->vq)) {
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return;
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}
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blk_io_unplug(s->conf->conf.blk);
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event_notifier_set(s->guest_notifier);
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}
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static void data_plane_set_up_op_blockers(VirtIOBlockDataPlane *s)
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@ -260,7 +190,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
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BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
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VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
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VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
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VirtQueue *vq;
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int r;
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if (vblk->dataplane_started || s->starting) {
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@ -268,11 +197,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
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}
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s->starting = true;
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vq = virtio_get_queue(s->vdev, 0);
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if (!vring_setup(&s->vring, s->vdev, 0)) {
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goto fail_vring;
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}
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s->vq = virtio_get_queue(s->vdev, 0);
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/* Set up guest notifier (irq) */
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r = k->set_guest_notifiers(qbus->parent, 1, true);
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@ -281,7 +206,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
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"ensure -enable-kvm is set\n", r);
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goto fail_guest_notifiers;
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}
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s->guest_notifier = virtio_queue_get_guest_notifier(vq);
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s->guest_notifier = virtio_queue_get_guest_notifier(s->vq);
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/* Set up virtqueue notify */
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r = k->set_host_notifier(qbus->parent, 0, true);
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@ -289,10 +214,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
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fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
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goto fail_host_notifier;
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}
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s->host_notifier = *virtio_queue_get_host_notifier(vq);
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s->saved_complete_request = vblk->complete_request;
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vblk->complete_request = complete_request_vring;
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s->starting = false;
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vblk->dataplane_started = true;
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@ -301,20 +222,17 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
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blk_set_aio_context(s->conf->conf.blk, s->ctx);
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/* Kick right away to begin processing requests already in vring */
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event_notifier_set(virtio_queue_get_host_notifier(vq));
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event_notifier_set(virtio_queue_get_host_notifier(s->vq));
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/* Get this show started by hooking up our callbacks */
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aio_context_acquire(s->ctx);
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aio_set_event_notifier(s->ctx, &s->host_notifier, true,
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handle_notify);
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virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, true, true);
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aio_context_release(s->ctx);
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return;
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fail_host_notifier:
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k->set_guest_notifiers(qbus->parent, 1, false);
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fail_guest_notifiers:
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vring_teardown(&s->vring, s->vdev, 0);
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fail_vring:
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s->disabled = true;
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s->starting = false;
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vblk->dataplane_started = true;
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@ -338,24 +256,18 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
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return;
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}
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s->stopping = true;
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vblk->complete_request = s->saved_complete_request;
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trace_virtio_blk_data_plane_stop(s);
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aio_context_acquire(s->ctx);
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/* Stop notifications for new requests from guest */
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aio_set_event_notifier(s->ctx, &s->host_notifier, true, NULL);
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virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, false, false);
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/* Drain and switch bs back to the QEMU main loop */
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blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
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aio_context_release(s->ctx);
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/* Sync vring state back to virtqueue so that non-dataplane request
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* processing can continue when we disable the host notifier below.
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*/
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vring_teardown(&s->vring, s->vdev, 0);
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k->set_host_notifier(qbus->parent, 0, false);
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/* Clean up guest notifier (irq) */
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