79 lines
3.3 KiB
Diff
79 lines
3.3 KiB
Diff
|
From da3a5afa41790ae913d41cfcdc3c6a8731ae3fe8 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Hanna Czenczek <hreitz@redhat.com>
|
||
|
|
Date: Fri, 2 Feb 2024 16:31:56 +0100
|
||
|
|
Subject: [PATCH 1/6] virtio-scsi: Attach event vq notifier with no_poll
|
||
|
|
|
||
|
|
RH-Author: Hanna Czenczek <hreitz@redhat.com>
|
||
|
|
RH-MergeRequest: 223: virtio: Re-enable notifications after drain
|
||
|
|
RH-Jira: RHEL-3934
|
||
|
|
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
|
||
|
|
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
|
||
|
|
RH-Commit: [1/3] d29b461a0a4b584af0ee80fb3f9e45c92ea88eb0 (hreitz/qemu-kvm-c-9-s)
|
||
|
|
|
||
|
|
As of commit 38738f7dbbda90fbc161757b7f4be35b52205552 ("virtio-scsi:
|
||
|
|
don't waste CPU polling the event virtqueue"), we only attach an io_read
|
||
|
|
notifier for the virtio-scsi event virtqueue instead, and no polling
|
||
|
|
notifiers. During operation, the event virtqueue is typically
|
||
|
|
non-empty, but none of the buffers are intended to be used immediately.
|
||
|
|
Instead, they only get used when certain events occur. Therefore, it
|
||
|
|
makes no sense to continuously poll it when non-empty, because it is
|
||
|
|
supposed to be and stay non-empty.
|
||
|
|
|
||
|
|
We do this by using virtio_queue_aio_attach_host_notifier_no_poll()
|
||
|
|
instead of virtio_queue_aio_attach_host_notifier() for the event
|
||
|
|
virtqueue.
|
||
|
|
|
||
|
|
Commit 766aa2de0f29b657148e04599320d771c36fd126 ("virtio-scsi: implement
|
||
|
|
BlockDevOps->drained_begin()") however has virtio_scsi_drained_end() use
|
||
|
|
virtio_queue_aio_attach_host_notifier() for all virtqueues, including
|
||
|
|
the event virtqueue. This can lead to it being polled again, undoing
|
||
|
|
the benefit of commit 38738f7dbbda90fbc161757b7f4be35b52205552.
|
||
|
|
|
||
|
|
Fix it by using virtio_queue_aio_attach_host_notifier_no_poll() for the
|
||
|
|
event virtqueue.
|
||
|
|
|
||
|
|
Reported-by: Fiona Ebner <f.ebner@proxmox.com>
|
||
|
|
Fixes: 766aa2de0f29b657148e04599320d771c36fd126
|
||
|
|
("virtio-scsi: implement BlockDevOps->drained_begin()")
|
||
|
|
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
|
||
|
|
Tested-by: Fiona Ebner <f.ebner@proxmox.com>
|
||
|
|
Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>
|
||
|
|
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
|
||
|
|
Message-ID: <20240202153158.788922-2-hreitz@redhat.com>
|
||
|
|
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
|
||
|
|
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
|
||
|
|
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
|
||
|
|
(cherry picked from commit c42c3833e0cfdf2b80fb3ca410acfd392b6874ab)
|
||
|
|
---
|
||
|
|
hw/scsi/virtio-scsi.c | 7 ++++++-
|
||
|
|
1 file changed, 6 insertions(+), 1 deletion(-)
|
||
|
|
|
||
|
|
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
|
||
|
|
index ca365a70e9..9943186917 100644
|
||
|
|
--- a/hw/scsi/virtio-scsi.c
|
||
|
|
+++ b/hw/scsi/virtio-scsi.c
|
||
|
|
@@ -1149,6 +1149,7 @@ static void virtio_scsi_drained_begin(SCSIBus *bus)
|
||
|
|
static void virtio_scsi_drained_end(SCSIBus *bus)
|
||
|
|
{
|
||
|
|
VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
|
||
|
|
+ VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
|
||
|
|
VirtIODevice *vdev = VIRTIO_DEVICE(s);
|
||
|
|
uint32_t total_queues = VIRTIO_SCSI_VQ_NUM_FIXED +
|
||
|
|
s->parent_obj.conf.num_queues;
|
||
|
|
@@ -1166,7 +1167,11 @@ static void virtio_scsi_drained_end(SCSIBus *bus)
|
||
|
|
|
||
|
|
for (uint32_t i = 0; i < total_queues; i++) {
|
||
|
|
VirtQueue *vq = virtio_get_queue(vdev, i);
|
||
|
|
- virtio_queue_aio_attach_host_notifier(vq, s->ctx);
|
||
|
|
+ if (vq == vs->event_vq) {
|
||
|
|
+ virtio_queue_aio_attach_host_notifier_no_poll(vq, s->ctx);
|
||
|
|
+ } else {
|
||
|
|
+ virtio_queue_aio_attach_host_notifier(vq, s->ctx);
|
||
|
|
+ }
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
--
|
||
|
|
2.39.3
|
||
|
|
|