Re: [PATCH RFC 12/19] vfio-user: probe remote device's BARs

[Alex Williamson]

On Sun, 18 Jul 2021 23:27:51 -0700
Elena Ufimtseva <elena.ufimtseva@oracle.com> wrote:
> @@ -3442,6 +3448,22 @@ static void vfio_user_pci_realize(PCIDevice *pdev, 
> Error **errp)
>      /* QEMU can also add or extend BARs */
>      memset(vdev->emulated_config_bits + PCI_BASE_ADDRESS_0, 0xff, 6 * 4);
>  
> +    /*
> +     * Local QEMU overrides aren't allowed
> +     * They must be done in the device process
> +     */
> +    if (pdev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION) {
> +        error_setg(errp, "Multi-function must be specified by device 
> process");
> +        goto error;
> +    }
> +    if (pdev->romfile) {
> +        error_setg(errp, "Romfile must be specified by device process");
> +        goto error;
> +    }

For what reason?  PCI functions can operate completely independently,
there could be different servers for different functions, a QEMU user
may wish to apply a different option ROM image than provided by the
server.  This all creates unnecessary incompatibilities.  Thanks,

Alex