Re: [PATCH rc] iommu/arm-smmu-v3: Drain in-flight fault handlers

[Will Deacon <will@kernel.org>]

On Tue, Mar 24, 2026 at 11:17:16AM -0300, Jason Gunthorpe wrote:
> On Tue, Mar 24, 2026 at 02:04:03PM +0000, Will Deacon wrote:
> > Sorry, that was sloppy terminology on my part. I'm trying to reason about
> > faults that are generated by accesses that were translated with the
> > page-tables of the old domain being reported once we think we are using
> > the new domain.
> 
> It doesn't matter.
> 
> If a concurrent fault is resolving on the old domain and it completes
> after the STE is in the new domain the device will restart and if the
> IOVA is still non-present it will refault. This is normal and fine.
> 
> If it is resolving on the new domain and the new domain has a present
> PTE so the PRI is spurious then the fault handler should NOP it and
> restart the device.

Hmm, I can see that working out if both domains expect faults, but if
I'm switching to a domain without a handler wouldn't I be better off
draining the outstanding faults generated on the old domain first?
Otherwise, won't we see a bunch of noise from the eventq thread as
it dumps unexpected events to the console?

Will