Re: [PATCH v2 2/2] virtio-iommu-pci: force virtio version 1

[Cornelia Huck <cohuck@redhat.com>]

On Tue,  8 Sep 2020 21:33:09 +0200
Eric Auger <eric.auger@redhat.com> wrote:

> Commit 9b3a35ec82 ("virtio: verify that legacy support is not
> accidentally on") added a safety check that requires to set
> 'disable-legacy=on' on virtio-iommu-pci:
> 
> qemu-system-aarch64: -device virtio-iommu-pci: device is modern-only,
> use disable-legacy=on
> 
> virtio-iommu was introduced after the release of VIRTIO 1.0
> specifications, so it should be 'modern-only'.
> 
> This patch forces virtio version 1 and removes the 'transitional_name'
> property removing the need to specify 'disable-legacy=on' on
> virtio-iommu-pci device.

Not sure whether this patch has been queued already, and how much we
care about migration compatibility for virtio-iommu, but would it make
sense to force modern on 5.1+ compat machines only? (see
https://lore.kernel.org/qemu-devel/20200918074710.27810-1-sgarzare@redhat.com/)

> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> 
> ---
> v1 -> v2:
> - Added Connie's R-b
> ---
>  hw/virtio/virtio-iommu-pci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/virtio-iommu-pci.c b/hw/virtio/virtio-iommu-pci.c
> index ba62d60a0a..3b6f7a11c6 100644
> --- a/hw/virtio/virtio-iommu-pci.c
> +++ b/hw/virtio/virtio-iommu-pci.c
> @@ -68,6 +68,7 @@ static void virtio_iommu_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
>      object_property_set_link(OBJECT(dev), "primary-bus",
>                               OBJECT(pci_get_bus(&vpci_dev->pci_dev)),
>                               &error_abort);
> +    virtio_pci_force_virtio_1(vpci_dev);
>      qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
>  }
>  
> @@ -97,7 +98,6 @@ static void virtio_iommu_pci_instance_init(Object *obj)
>  static const VirtioPCIDeviceTypeInfo virtio_iommu_pci_info = {
>      .base_name             = TYPE_VIRTIO_IOMMU_PCI,
>      .generic_name          = "virtio-iommu-pci",
> -    .transitional_name     = "virtio-iommu-pci-transitional",
>      .non_transitional_name = "virtio-iommu-pci-non-transitional",
>      .instance_size = sizeof(VirtIOIOMMUPCI),
>      .instance_init = virtio_iommu_pci_instance_init,