[PATCH] virtio: update queue size on guest write

[PATCH] virtio: update queue size on guest write

[Michael S. Tsirkin]

Some guests read back queue size after writing it.
Update the size immediatly upon write otherwise
they get confused.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-pci.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index c6b47a9c73..e5c759e19e 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1256,6 +1256,8 @@ static void virtio_pci_common_write(void *opaque, hwaddr addr,
         break;
     case VIRTIO_PCI_COMMON_Q_SIZE:
         proxy->vqs[vdev->queue_sel].num = val;
+        virtio_queue_set_num(vdev, vdev->queue_sel,
+                             proxy->vqs[vdev->queue_sel].num);
         break;
     case VIRTIO_PCI_COMMON_Q_MSIX:
         msix_vector_unuse(&proxy->pci_dev,
-- 
MST

Re: [PATCH] virtio: update queue size on guest write

[Stefano Garzarella]

On Fri, Dec 13, 2019 at 09:24:03AM -0500, Michael S. Tsirkin wrote:
> Some guests read back queue size after writing it.
> Update the size immediatly upon write otherwise
> they get confused.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/virtio/virtio-pci.c | 2 ++
>  1 file changed, 2 insertions(+)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>


Just a question, should we do the same in virtio-mmio?

Maybe doing virtio_queue_set_num() in any case (legacy and non-legacy)
during VIRTIO_MMIO_QUEUE_NUM writing.

Thanks,
Stefano

> 
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index c6b47a9c73..e5c759e19e 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1256,6 +1256,8 @@ static void virtio_pci_common_write(void *opaque, hwaddr addr,
>          break;
>      case VIRTIO_PCI_COMMON_Q_SIZE:
>          proxy->vqs[vdev->queue_sel].num = val;
> +        virtio_queue_set_num(vdev, vdev->queue_sel,
> +                             proxy->vqs[vdev->queue_sel].num);
>          break;
>      case VIRTIO_PCI_COMMON_Q_MSIX:
>          msix_vector_unuse(&proxy->pci_dev,
> -- 
> MST
> 
> 

-- 

Re: [PATCH] virtio: update queue size on guest write

[Michael S. Tsirkin]

On Mon, Dec 16, 2019 at 09:50:13AM +0100, Stefano Garzarella wrote:
> On Fri, Dec 13, 2019 at 09:24:03AM -0500, Michael S. Tsirkin wrote:
> > Some guests read back queue size after writing it.
> > Update the size immediatly upon write otherwise
> > they get confused.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  hw/virtio/virtio-pci.c | 2 ++
> >  1 file changed, 2 insertions(+)
> 
> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
> 
> 
> Just a question, should we do the same in virtio-mmio?
> 
> Maybe doing virtio_queue_set_num() in any case (legacy and non-legacy)
> during VIRTIO_MMIO_QUEUE_NUM writing.
> 
> Thanks,
> Stefano

I guess it makes sense ...

> > 
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index c6b47a9c73..e5c759e19e 100644
> > --- a/hw/virtio/virtio-pci.c
> > +++ b/hw/virtio/virtio-pci.c
> > @@ -1256,6 +1256,8 @@ static void virtio_pci_common_write(void *opaque, hwaddr addr,
> >          break;
> >      case VIRTIO_PCI_COMMON_Q_SIZE:
> >          proxy->vqs[vdev->queue_sel].num = val;
> > +        virtio_queue_set_num(vdev, vdev->queue_sel,
> > +                             proxy->vqs[vdev->queue_sel].num);
> >          break;
> >      case VIRTIO_PCI_COMMON_Q_MSIX:
> >          msix_vector_unuse(&proxy->pci_dev,
> > -- 
> > MST
> > 
> > 
> 
> --