Re: [PATCH 1/2] s390x/pci: bypass vfio DMA counting when using cdev

[Philippe Mathieu-Daudé]

On 9/11/23 23:53, Matthew Rosato wrote:
> The current code assumes that there is always a vfio group, but
> that's no longer guaranteed with the iommufd backend when using
> cdev.  In this case, we don't need to track the vfio dma limit
> anyway.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
>   hw/s390x/s390-pci-vfio.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
> index 59a2e03873..7218583883 100644
> --- a/hw/s390x/s390-pci-vfio.c
> +++ b/hw/s390x/s390-pci-vfio.c
> @@ -66,7 +66,11 @@ S390PCIDMACount *s390_pci_start_dma_count(S390pciState *s,
>   
>       assert(vpdev);
>   

Matter of taste, simpler as:

       if (!vpdev->vbasedev.group) {
           return NULL;
       }

> -    id = vpdev->vbasedev.group->container->fd;

and this line isn't changed.

> +    if (vpdev->vbasedev.group) {
> +        id = vpdev->vbasedev.group->container->fd;
> +    } else {
> +        return NULL;
> +    }
>   
>       if (!s390_pci_update_dma_avail(id, &avail)) {
>           return NULL;