73 lines
2.6 KiB
Diff
73 lines
2.6 KiB
Diff
From f62b56c68d50a149a07e15797bf3605e63b2c501 Mon Sep 17 00:00:00 2001
|
|
From: Stefan Hajnoczi <stefanha@redhat.com>
|
|
Date: Mon, 22 Jan 2024 12:26:25 -0500
|
|
Subject: [PATCH 4/6] virtio-blk: avoid using ioeventfd state in irqfd
|
|
conditional
|
|
|
|
RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
|
|
RH-MergeRequest: 224: virtio-blk: avoid using ioeventfd state in irqfd conditional
|
|
RH-Jira: RHEL-15394
|
|
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
|
|
RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
|
|
RH-Commit: [1/1] 8f24084669db52457e55e2523b9f56f5560dd6ce (stefanha/centos-stream-qemu-kvm)
|
|
|
|
Requests that complete in an IOThread use irqfd to notify the guest
|
|
while requests that complete in the main loop thread use the traditional
|
|
qdev irq code path. The reason for this conditional is that the irq code
|
|
path requires the BQL:
|
|
|
|
if (s->ioeventfd_started && !s->ioeventfd_disabled) {
|
|
virtio_notify_irqfd(vdev, req->vq);
|
|
} else {
|
|
virtio_notify(vdev, req->vq);
|
|
}
|
|
|
|
There is a corner case where the conditional invokes the irq code path
|
|
instead of the irqfd code path:
|
|
|
|
static void virtio_blk_stop_ioeventfd(VirtIODevice *vdev)
|
|
{
|
|
...
|
|
/*
|
|
* 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);
|
|
|
|
During blk_drain() the conditional produces the wrong result because
|
|
ioeventfd_started is false.
|
|
|
|
Use qemu_in_iothread() instead of checking the ioeventfd state.
|
|
|
|
Cc: qemu-stable@nongnu.org
|
|
Buglink: https://issues.redhat.com/browse/RHEL-15394
|
|
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
|
|
Message-ID: <20240122172625.415386-1-stefanha@redhat.com>
|
|
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
|
|
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
|
|
(cherry picked from commit bfa36802d1704fc413c590ebdcc4e5ae0eacf439)
|
|
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
|
|
---
|
|
hw/block/virtio-blk.c | 2 +-
|
|
1 file changed, 1 insertion(+), 1 deletion(-)
|
|
|
|
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
|
|
index 7fdeaf2d12..2ae2f6a823 100644
|
|
--- a/hw/block/virtio-blk.c
|
|
+++ b/hw/block/virtio-blk.c
|
|
@@ -66,7 +66,7 @@ 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->ioeventfd_started && !s->ioeventfd_disabled) {
|
|
+ if (qemu_in_iothread()) {
|
|
virtio_notify_irqfd(vdev, req->vq);
|
|
} else {
|
|
virtio_notify(vdev, req->vq);
|
|
--
|
|
2.39.3
|
|
|