Re: [PATCH 1/2] vfio: Do not register any IOMMU_NOTIFIER_DEVIOTLB_UNMAP notifier

[Alex Williamson]

On Tue,  9 Feb 2021 22:32:32 +0100
Eric Auger <eric.auger@redhat.com> wrote:

> In an attempt to fix smmu/virtio-iommu - vhost regression, commit
> 958ec334bca3 ("vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support")
> broke virtio-iommu integration. This is due to the fact VFIO registers
> IOMMU_NOTIFIER_ALL notifiers, which includes IOMMU_NOTIFIER_DEVIOTLB_UNMAP
> and this latter now is rejected by the virtio-iommu. As a consequence,
> the registration fails. VHOST behaves like a device with an ATC cache. The
> VFIO device does not support this scheme yet.
> 
> Let's register only legacy MAP and UNMAP notifiers.
> 
> Fixes: 958ec334bca3 ("vhost: Unbreak SMMU and virtio-iommu on dev-iotlb 
> support")
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
>  hw/vfio/common.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 6ff1daa763..a50b10c801 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -787,7 +787,7 @@ static void vfio_listener_region_add(MemoryListener 
> *listener,
>          iommu_idx = memory_region_iommu_attrs_to_index(iommu_mr,
>                                                         
> MEMTXATTRS_UNSPECIFIED);
>          iommu_notifier_init(&giommu->n, vfio_iommu_map_notify,
> -                            IOMMU_NOTIFIER_ALL,
> +                            IOMMU_NOTIFIER_IOTLB_EVENTS,
>                              section->offset_within_region,
>                              int128_get64(llend),
>                              iommu_idx);

Acked-by: Alex Williamson <alex.williamson@redhat.com>