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

[Baolu Lu <baolu.lu@linux.intel.com>]

On 11/6/2026 6:01 AM, Vinicius Costa Gomes wrote:
> Lu Baolu<baolu.lu@linux.intel.com> 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