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64 lines
2.8 KiB
64 lines
2.8 KiB
8 months ago
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From 22730552442003e81c8c508c3e7ebacf647e4e75 Mon Sep 17 00:00:00 2001
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Fri, 19 Jan 2024 08:57:48 -0500
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Subject: [PATCH 19/22] virtio-blk: always set ioeventfd during startup
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RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
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RH-MergeRequest: 219: virtio-blk: add iothread-vq-mapping parameter
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RH-Jira: RHEL-17369 RHEL-20764 RHEL-7356
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
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RH-Commit: [15/17] 5f7142aeaa54fda41bd5c4fd3222fd8e3e18f370 (stefanha/centos-stream-qemu-kvm)
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When starting ioeventfd it is common practice to set the event notifier
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so that the ioeventfd handler is triggered to run immediately. There may
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be no requests waiting to be processed, but the idea is that if a
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request snuck in then we guarantee that it will be detected.
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One scenario where self-triggering the ioeventfd is necessary is when
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virtio_blk_handle_output() is called from a vCPU thread before the
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VIRTIO Device Status transitions to DRIVER_OK. In that case we need to
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self-trigger the ioeventfd so that the kick handled by the vCPU thread
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causes the vq AioContext thread to take over handling the request(s).
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Fixes: b6948ab01df0 ("virtio-blk: add iothread-vq-mapping parameter")
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Reported-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-ID: <20240119135748.270944-7-stefanha@redhat.com>
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Reviewed-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit d3f6f294aeadd5f88caf0155e4360808c95b3146)
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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hw/block/virtio-blk.c | 12 ++++++------
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1 file changed, 6 insertions(+), 6 deletions(-)
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diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
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index 81de06c9f6..0b9100b746 100644
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--- a/hw/block/virtio-blk.c
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+++ b/hw/block/virtio-blk.c
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@@ -1809,14 +1809,14 @@ static int virtio_blk_start_ioeventfd(VirtIODevice *vdev)
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smp_wmb(); /* paired with aio_notify_accept() on the read side */
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/* Get this show started by hooking up our callbacks */
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- if (!blk_in_drain(s->conf.conf.blk)) {
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- for (i = 0; i < nvqs; i++) {
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- VirtQueue *vq = virtio_get_queue(vdev, i);
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- AioContext *ctx = s->vq_aio_context[i];
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+ for (i = 0; i < nvqs; i++) {
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+ VirtQueue *vq = virtio_get_queue(vdev, i);
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+ AioContext *ctx = s->vq_aio_context[i];
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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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+ /* 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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+ if (!blk_in_drain(s->conf.conf.blk)) {
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virtio_queue_aio_attach_host_notifier(vq, ctx);
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}
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}
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--
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2.39.3
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