Re: [PATCH 1/2] iommu/vt-d: Set FPD when tearing down a PASID entry with fault_ignore

[Baolu Lu]

On 11/6/2026 6:01 AM, Vinicius Costa Gomes wrote:
> Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx> writes:
>
> >   static void
> >   pasid_cache_invalidation_with_pasid(struct intel_iommu *iommu,
> >   				    u16 did, u32 pasid)
> > @@ -253,7 +238,6 @@ void intel_pasid_tear_down_entry(struct intel_iommu *iommu, struct device *dev,
> >   
> >   	if (!pasid_pte_is_present(pte)) {
> >   		if (!pasid_pte_is_fault_disabled(pte)) {
> > -			WARN_ON(READ_ONCE(pte->val[0]) != 0);
> >   			spin_unlock(&iommu->lock);
> >   			return;
> >   		}
> > @@ -266,6 +250,8 @@ void intel_pasid_tear_down_entry(struct intel_iommu *iommu, struct device *dev,
> >   		 */
> >   		pasid_clear_entry(pte);
> >   		spin_unlock(&iommu->lock);
> > +		if (!ecap_coherent(iommu->ecap))
> > +			clflush_cache_range(pte, sizeof(*pte));
> >   		intel_iommu_drain_pasid_prq(dev, pasid);
> I think it's worth documenting in the commit message why both of these
> are needed, removing the warning and adding the flush.

Yes. I will add the following to the commit message:

 Also drop the WARN_ON() for a non-present entry without FPD. Since
 commit 75ed00055c05 a concurrent teardown can see such an entry before
 it is zeroed. Flush the cache after clearing an FPD-only entry, as
 other PASID entry updates do on non-coherent hardware.

Thanks,
baolu