Re: [PATCH 2/2] s390x/pci: indicate QEMU supports relaxed translation for passthrough

[Thomas Huth]

On 09/12/2024 20.29, Matthew Rosato wrote:
> Specifying this bit in the guest CLP response indicates that the guest
> can optionally choose to skip translation and instead use
> identity-mapped operations.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
>   hw/s390x/s390-pci-vfio.c        | 4 +++-
>   include/hw/s390x/s390-pci-clp.h | 1 +
>   2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
> index 7dbbc76823..51ac5ff3eb 100644
> --- a/hw/s390x/s390-pci-vfio.c
> +++ b/hw/s390x/s390-pci-vfio.c
> @@ -224,7 +224,9 @@ static void s390_pci_read_group(S390PCIBusDevice *pbdev,
>   
>           resgrp = &pbdev->pci_group->zpci_group;
>           if (cap->flags & VFIO_DEVICE_INFO_ZPCI_FLAG_REFRESH) {
> -            resgrp->fr = 1;
> +            resgrp->fr = (CLP_RSP_QPCIG_MASK_RTR | CLP_RSP_QPCIG_MASK_REFRESH);
> +        } else {
> +            resgrp->fr = CLP_RSP_QPCIG_MASK_RTR;
>           }

Just a matter of taste, but maybe easier to write it like this:

        resgrp->fr = CLP_RSP_QPCIG_MASK_RTR;
        if (cap->flags & VFIO_DEVICE_INFO_ZPCI_FLAG_REFRESH) {
            resgrp->fr |= CLP_RSP_QPCIG_MASK_REFRESH;
        }

?

 Thomas