Re: [PATCH v1 2/2] iommu/arm-smmu-v3: Recover ATC invalidate timeouts

Jason Gunthorpe
2026-03-11T12:12:50Z

On Tue, Mar 10, 2026 at 08:00:45PM +0000, Samiullah Khawaja wrote:
> On Fri, Mar 06, 2026 at 04:26:52PM -0400, Jason Gunthorpe wrote:
> > On Fri, Mar 06, 2026 at 08:22:08PM +0000, Samiullah Khawaja wrote:
> >
> > > But do you think doing the timeout logic without fencing would be good
> > > enough?
> >
> > It is what ARM and AMD do, so I wouldn't object to it.
>
> I think without any back pressure to the caller, a device will be able
> to fill the invalidation queue with device IOTLB invalidations that get
> stuck until the HW timeout occurs.

Yes, all drivers have this problem currently.

Jason