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Re: [Qemu-devel] [PATCH] vhost-user-blk: start vhost when guest kicks
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH] vhost-user-blk: start vhost when guest kicks |
Date: |
Tue, 5 Jun 2018 17:23:15 +0300 |
On Tue, Jun 05, 2018 at 09:56:10PM +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 would cause
> that those old guests fail to boot with vhost-user-blk device.
>
> To fix it, start vhost when guest kicks instead of waiting for .set_status().
>
> Signed-off-by: Yongji Xie <address@hidden>
> Signed-off-by: Chai Wen <address@hidden>
> Signed-off-by: Ni Xun <address@hidden>
Can we at least limit this to when virtio 1.0 has not
been negotiated?
> ---
> hw/block/vhost-user-blk.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
> index d755223..8fd0e6f 100644
> --- a/hw/block/vhost-user-blk.c
> +++ b/hw/block/vhost-user-blk.c
> @@ -217,7 +217,27 @@ 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 (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