Re: [PATCH V5 17/25] vfio-pci: cpr part 2

[Alex Williamson]

On Wed,  7 Jul 2021 10:20:26 -0700
Steve Sistare <steven.sistare@oracle.com> wrote:

> Finish cpr for vfio-pci by preserving eventfd's and vector state.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  hw/vfio/pci.c | 118 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 116 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 0f5c542..07bd360 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
...
> @@ -3295,14 +3329,91 @@ static void vfio_merge_config(VFIOPCIDevice
*vdev)
>      g_free(phys_config);
>  }
>  
> +static int vfio_pci_pre_save(void *opaque)
> +{
> +    VFIOPCIDevice *vdev = opaque;
> +    PCIDevice *pdev = &vdev->pdev;
> +    int i;
> +
> +    if (vfio_pci_read_config(pdev, PCI_INTERRUPT_PIN, 1)) {
> +        error_report("%s: cpr does not support vfio-pci INTX",
> +                     vdev->vbasedev.name);
> +    }

You're not only not supporting INTx, but devices that support INTx, so
this only works on VFs.  Why?  Is this just out of scope or is there
something fundamentally difficult about it?

This makes me suspect there's a gap in INTx routing setup if it's more
than just another eventfd to store and setup.  If we hot-add a device
using INTx after cpr restart, are we going to find problems?  Thanks,

Alex