On Tue, Aug 27, 2024 at 01:12:27PM -0700, Nicolin Chen wrote:

quoted

@@ -2693,6 +2718,15 @@ static int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state,
 		 * one of them.
 		 */
 		spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+		if (smmu_domain->enforce_cache_coherency &&
+		    !(dev_iommu_fwspec_get(master->dev)->flags &
+		      IOMMU_FWSPEC_PCI_RC_CANWBS)) {

How about a small dev_enforce_cache_coherency() helper?

I added a

+static bool arm_smmu_master_canwbs(struct arm_smmu_master *master)
+{
+       return dev_iommu_fwspec_get(master->dev)->flags &
+              IOMMU_FWSPEC_PCI_RC_CANWBS;
+}
+

quoted

+			kfree(master_domain);
+			spin_unlock_irqrestore(&smmu_domain->devices_lock,
+					       flags);
+			return -EINVAL;

kfree() doesn't need to be locked.

Yep

Thanks,
Jason