* [Qemu-devel] [PATCH v2] vhost-user-blk: start vhost when guest kicks
@ 2018-06-06 13:24 Yongji Xie
2018-06-07 12:50 ` Stefan Hajnoczi
0 siblings, 1 reply; 2+ messages in thread
From: Yongji Xie @ 2018-06-06 13:24 UTC (permalink / raw)
To: mst, stefanha, changpeng.liu; +Cc: qemu-devel, chaiwen, nixun, elohimes
Some old guests (before commit 7a11370e5: "virtio_blk: enable VQs early")
kick virtqueue before setting VIRTIO_CONFIG_S_DRIVER_OK. This violates
the virtio spec. But virtio 1.0 transitional devices support this behaviour.
So we should start vhost when guest kicks in this case.
Signed-off-by: Yongji Xie <xieyongji@baidu.com>
Signed-off-by: Chai Wen <chaiwen@baidu.com>
Signed-off-by: Ni Xun <nixun@baidu.com>
---
hw/block/vhost-user-blk.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index d755223..1451940 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -217,7 +217,32 @@ static uint64_t vhost_user_blk_get_features(VirtIODevice *vdev,
static void vhost_user_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
+ VHostUserBlk *s = VHOST_USER_BLK(vdev);
+ int i;
+
+ if (!(virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1) &&
+ !virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1))) {
+ return;
+ }
+
+ if (s->dev.started) {
+ return;
+ }
+
+ /* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
+ * vhost here instead of waiting for .set_status().
+ */
+ vhost_user_blk_start(vdev);
+ /* Kick right away to begin processing requests already in vring */
+ for (i = 0; i < s->dev.nvqs; i++) {
+ VirtQueue *kick_vq = virtio_get_queue(vdev, i);
+
+ if (!virtio_queue_get_desc_addr(vdev, i)) {
+ continue;
+ }
+ event_notifier_set(virtio_queue_get_host_notifier(kick_vq));
+ }
}
static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
--
1.7.9.5
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [PATCH v2] vhost-user-blk: start vhost when guest kicks
2018-06-06 13:24 [Qemu-devel] [PATCH v2] vhost-user-blk: start vhost when guest kicks Yongji Xie
@ 2018-06-07 12:50 ` Stefan Hajnoczi
0 siblings, 0 replies; 2+ messages in thread
From: Stefan Hajnoczi @ 2018-06-07 12:50 UTC (permalink / raw)
To: Yongji Xie; +Cc: mst, stefanha, changpeng.liu, nixun, qemu-devel, chaiwen
[-- Attachment #1: Type: text/plain, Size: 657 bytes --]
On Wed, Jun 06, 2018 at 09:24:48PM +0800, Yongji Xie wrote:
> Some old guests (before commit 7a11370e5: "virtio_blk: enable VQs early")
> kick virtqueue before setting VIRTIO_CONFIG_S_DRIVER_OK. This violates
> the virtio spec. But virtio 1.0 transitional devices support this behaviour.
> So we should start vhost when guest kicks in this case.
>
> Signed-off-by: Yongji Xie <xieyongji@baidu.com>
> Signed-off-by: Chai Wen <chaiwen@baidu.com>
> Signed-off-by: Ni Xun <nixun@baidu.com>
> ---
> hw/block/vhost-user-blk.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-06-06 13:24 [Qemu-devel] [PATCH v2] vhost-user-blk: start vhost when guest kicks Yongji Xie
2018-06-07 12:50 ` Stefan Hajnoczi
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