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authorStefan Hajnoczi <stefanha@redhat.com>2023-09-13 16:00:45 -0400
committerKevin Wolf <kwolf@redhat.com>2023-10-31 15:42:17 +0100
commit073458da5619c8914a91440ef243d1e2b888c1b7 (patch)
tree52885acd863d0df51f2f0e17231c0d0f3684b547 /hw/block
parent84d61e5f36a73ed24742b7c7cf7b811e456dd024 (diff)
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virtio-blk: remove batch notification BH
There is a batching mechanism for virtio-blk Used Buffer Notifications that is no longer needed because the previous commit added batching to virtio_notify_irqfd(). Note that this mechanism was rarely used in practice because it is only enabled when EVENT_IDX is not negotiated by the driver. Modern drivers enable EVENT_IDX. Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-ID: <20230913200045.1024233-5-stefanha@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'hw/block')
-rw-r--r--hw/block/dataplane/virtio-blk.c48
1 files changed, 1 insertions, 47 deletions
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index da36fcf..f83bb0f 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -31,9 +31,6 @@ struct VirtIOBlockDataPlane {
VirtIOBlkConf *conf;
VirtIODevice *vdev;
- QEMUBH *bh; /* bh for guest notification */
- unsigned long *batch_notify_vqs;
- bool batch_notifications;
/* Note that these EventNotifiers are assigned by value. This is
* fine as long as you do not call event_notifier_cleanup on them
@@ -47,36 +44,7 @@ struct VirtIOBlockDataPlane {
/* Raise an interrupt to signal guest, if necessary */
void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq)
{
- if (s->batch_notifications) {
- set_bit(virtio_get_queue_index(vq), s->batch_notify_vqs);
- qemu_bh_schedule(s->bh);
- } else {
- virtio_notify_irqfd(s->vdev, vq);
- }
-}
-
-static void notify_guest_bh(void *opaque)
-{
- VirtIOBlockDataPlane *s = opaque;
- unsigned nvqs = s->conf->num_queues;
- unsigned long bitmap[BITS_TO_LONGS(nvqs)];
- unsigned j;
-
- memcpy(bitmap, s->batch_notify_vqs, sizeof(bitmap));
- memset(s->batch_notify_vqs, 0, sizeof(bitmap));
-
- for (j = 0; j < nvqs; j += BITS_PER_LONG) {
- unsigned long bits = bitmap[j / BITS_PER_LONG];
-
- while (bits != 0) {
- unsigned i = j + ctzl(bits);
- VirtQueue *vq = virtio_get_queue(s->vdev, i);
-
- virtio_notify_irqfd(s->vdev, vq);
-
- bits &= bits - 1; /* clear right-most bit */
- }
- }
+ virtio_notify_irqfd(s->vdev, vq);
}
/* Context: QEMU global mutex held */
@@ -126,9 +94,6 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
} else {
s->ctx = qemu_get_aio_context();
}
- s->bh = aio_bh_new_guarded(s->ctx, notify_guest_bh, s,
- &DEVICE(vdev)->mem_reentrancy_guard);
- s->batch_notify_vqs = bitmap_new(conf->num_queues);
*dataplane = s;
@@ -146,8 +111,6 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
vblk = VIRTIO_BLK(s->vdev);
assert(!vblk->dataplane_started);
- g_free(s->batch_notify_vqs);
- qemu_bh_delete(s->bh);
if (s->iothread) {
object_unref(OBJECT(s->iothread));
}
@@ -173,12 +136,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
s->starting = true;
- if (!virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
- s->batch_notifications = true;
- } else {
- s->batch_notifications = false;
- }
-
/* Set up guest notifier (irq) */
r = k->set_guest_notifiers(qbus->parent, nvqs, true);
if (r != 0) {
@@ -370,9 +327,6 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
aio_context_release(s->ctx);
- qemu_bh_cancel(s->bh);
- notify_guest_bh(s); /* final chance to notify guest */
-
/* Clean up guest notifier (irq) */
k->set_guest_notifiers(qbus->parent, nvqs, false);