Re: [PATCH] virtio-vga: fix virtio-vga bar ordering

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Apr 21, 2020 at 11:48:53PM +0200, Anthoine Bourgeois wrote:
> With virtio-vga, pci bar are reordered. Bar #2 is used for compatibility
> with stdvga. By default, bar #2 is used by virtio modern io bar.
> This bar is the last one introduce in the virtio pci bar layout and it's
> crushed by the virtio-vga reordering. So virtio-vga and
> modern-pio-notify are incompatible because virtio-vga failed to
> initialize with this option.
> 
> This fix exchange the modern io bar with the modern memory bar,
> replacing the msix bar that is never impacted anyway.
> 
> Signed-off-by: Anthoine Bourgeois <anthoine.bourgeois@gmail.com>

Such changes generally need to be tied to machine version.


> ---
>  hw/display/virtio-vga.c | 2 +-
>  hw/virtio/virtio-pci.c  | 1 +
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/display/virtio-vga.c b/hw/display/virtio-vga.c
> index 2b4c2aa126..f5f8737c60 100644
> --- a/hw/display/virtio-vga.c
> +++ b/hw/display/virtio-vga.c
> @@ -113,7 +113,7 @@ static void virtio_vga_base_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
>       * the stdvga mmio registers at the start of bar #2.
>       */
>      vpci_dev->modern_mem_bar_idx = 2;
> -    vpci_dev->msix_bar_idx = 4;
> +    vpci_dev->modern_io_bar_idx = 4;
>  
>      if (!(vpci_dev->flags & VIRTIO_PCI_FLAG_PAGE_PER_VQ)) {
>          /*
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 4cb784389c..9c5efaa06e 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1705,6 +1705,7 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
>       *
>       *   region 0   --  virtio legacy io bar
>       *   region 1   --  msi-x bar
> +     *   region 2   --  virtio modern io bar
>       *   region 4+5 --  virtio modern memory (64bit) bar
>       *
>       */
> -- 
> 2.20.1