Re: [PATCH V2 0/5] Fix UNMAP notifier for intel-iommu

[Peter Xu]

On Thu, Feb 23, 2023 at 02:59:19PM +0800, Jason Wang wrote:
> Hi All:
> 
> According to ATS, device should work if ATS is disabled. This is not
> correctly implemented in the current intel-iommu since it doesn't
> handle the UNMAP notifier correctly. This breaks the vhost-net +
> vIOMMU without dt.
> 
> The root casue is that the when there's a device IOTLB miss (note that
> it's not specific to PCI so it can work without ATS), Qemu doesn't
> build the IOVA tree, so when guest start an IOTLB invalidation, Qemu
> won't trigger the UNMAP notifier.
> 
> Fixing this by triggering UNMAP notifier in those cases.

Maybe someday we should start merging different places where we used the
same IOMMU_NOTIFIER_UNMAP event and also taking care of truncation of
notifier ranges within memory.c, but that can definitely be done later.

Reviewed-by: Peter Xu <peterx@redhat.com>

Thanks, Jason!

-- 
Peter Xu