Re: [PATCH v4 07/15] vfio/common: Track whether DMA Translation is enabled on the vIOMMU

[Eric Auger <eauger@redhat.com>]

Hi Joao,

On 6/22/23 23:48, Joao Martins wrote:
> vfio_get_group() allocates and fills the group/container/space on
> success which will store the AddressSpace inside the VFIOSpace struct.
VFIOAddressSpace
> Use the newly added pci_device_iommu_get_attr() to see if DMA
> translation is enabled or not. Assume that by default it is enabled.
> 
> Today, this means only intel-iommu supports it.
> 
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> ---
>  include/hw/vfio/vfio-common.h |  1 +
>  hw/vfio/pci.c                 | 15 ++++++++++++++-
>  2 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index eed244f25f34..f41860988d6b 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -70,6 +70,7 @@ typedef struct VFIOMigration {
>  
>  typedef struct VFIOAddressSpace {
>      AddressSpace *as;
> +    bool no_dma_translation;
>      QLIST_HEAD(, VFIOContainer) containers;
>      QLIST_ENTRY(VFIOAddressSpace) list;
>  } VFIOAddressSpace;
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 73874a94de12..8a98e6ffc480 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -2900,6 +2900,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>      VFIOPCIDevice *vdev = VFIO_PCI(pdev);
>      VFIODevice *vbasedev = &vdev->vbasedev;
>      VFIODevice *vbasedev_iter;
> +    VFIOAddressSpace *space;
>      VFIOGroup *group;
>      char *tmp, *subsys, group_path[PATH_MAX], *group_name;
>      Error *err = NULL;
> @@ -2907,7 +2908,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>      struct stat st;
>      int groupid;
>      int i, ret;
> -    bool is_mdev;
> +    bool is_mdev, dma_translation;
>      char uuid[UUID_FMT_LEN];
>      char *name;
>  
> @@ -2961,6 +2962,18 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>          goto error;
>      }
>  
> +    space = group->container->space;
> +
> +    /*
> +     * Support for toggling DMA translation is optional.
> +     * By default, DMA translation is assumed to be enabled i.e.
> +     * space::no_dma_translation is 0.
> +     */
> +    dma_translation = true;
nit can be set at init.
> +    pci_device_iommu_get_attr(pdev, IOMMU_ATTR_DMA_TRANSLATION,
> +                              &dma_translation);> +    space->no_dma_translation = !dma_translation;
> +
>      QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
>          if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) {
>              error_setg(errp, "device is already attached");

Thanks

Eric