Re: [PATCH 1/1] OvmfPkg: drop redundant VendorID check in VirtioMmioDeviceLib

["Laszlo Ersek" <lersek@redhat.com>]

Hi Leif,

On 09/12/20 18:40, Leif Lindholm wrote:
> There is a DEBUG warning printout in VirtioMmioDeviceLib if the current
> device's VendorID does not match the traditional 16-bit Red Hat PCIe
> vendor ID used with virtio-pci. The virtio-mmio vendor ID is 32-bit and
> has no connection to the PCIe registry.
> 
> Most specifically, this causes a bunch of noise when booting an AArch64
> QEMU platform, since QEMU's virtio-mmio implementation used 'QEMU' as
> the vendor ID:
> VirtioMmioInit: Warning:
>   The VendorId (0x554D4551) does not match the VirtIo VendorId (0x1AF4).

Good catch -- in QEMU, this has been the case since initial virtio-mmio
commit 4b52530be987 ("virtio: Implement MMIO based virtio transport",
2013-07-19); and indeed neither the virtio-0.9.5 spec, nor the "Legacy
MMIO" part of the 1.0 spec, require this vendor ID to be 0x1AF4.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thanks
Laszlo

> 
> Drop the warning message.
> 
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
> Signed-off-by: Leif Lindholm <leif@nuviainc.com>
> ---
>  .../VirtioMmioDeviceLib/VirtioMmioDevice.c        | 15 ---------------
>  1 file changed, 15 deletions(-)
> 
> diff --git a/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.c b/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.c
> index 2f20272c1445..6dbbba008c75 100644
> --- a/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.c
> +++ b/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.c
> @@ -58,7 +58,6 @@ VirtioMmioInit (
>    )
>  {
>    UINT32     MagicValue;
> -  UINT32     VendorId;
>    UINT32     Version;
>  
>    //
> @@ -84,20 +83,6 @@ VirtioMmioInit (
>      return EFI_UNSUPPORTED;
>    }
>  
> -  //
> -  // Double-check MMIO-specific values
> -  //
> -  VendorId = VIRTIO_CFG_READ (Device, VIRTIO_MMIO_OFFSET_VENDOR_ID);
> -  if (VendorId != VIRTIO_VENDOR_ID) {
> -    //
> -    // The ARM Base and Foundation Models do not report a valid VirtIo VendorId.
> -    // They return a value of 0x0 for the VendorId.
> -    //
> -    DEBUG((DEBUG_WARN, "VirtioMmioInit: Warning: The VendorId (0x%X) does not "
> -                       "match the VirtIo VendorId (0x%X).\n",
> -                       VendorId, VIRTIO_VENDOR_ID));
> -  }
> -
>    return EFI_SUCCESS;
>  }
>  
>