iommu/arm-smmu-v3: Invalidate ATC when detaching a device

We make the invalid assumption in arm_smmu_detach_dev() that the ATC is
clear after calling pci_disable_ats(). For one thing, only enabling the
PCIe ATS capability constitutes an implicit invalidation event, so the
comment was wrong. More importantly, the ATS capability isn't necessarily
disabled by pci_disable_ats() in a PF, if the associated VFs have ATS
enabled. Explicitly invalidate all ATC entries in arm_smmu_detach_dev().
The endpoint cannot form new ATC entries because STE.EATS is clear.

Fixes: 9ce27af ("iommu/arm-smmu-v3: Add support for PCI ATS")
Reported-by: Manoj Kumar <Manoj.Kumar3@arm.com>
Reported-by: Robin Murphy <Robin.Murphy@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/arm-smmu-v3.c

@@ -1892,9 +1892,13 @@ static int arm_smmu_enable_ats(struct arm_smmu_master *master)
 
 static void arm_smmu_disable_ats(struct arm_smmu_master *master)
 {
+	struct arm_smmu_cmdq_ent cmd;
+
 	if (!master->ats_enabled || !dev_is_pci(master->dev))
 		return;
 
+	arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd);
+	arm_smmu_atc_inv_master(master, &cmd);
 	pci_disable_ats(to_pci_dev(master->dev));
 	master->ats_enabled = false;
 }
@@ -1914,7 +1918,6 @@ static void arm_smmu_detach_dev(struct arm_smmu_master *master)
 	master->domain = NULL;
 	arm_smmu_install_ste_for_dev(master);
 
-	/* Disabling ATS invalidates all ATC entries */
 	arm_smmu_disable_ats(master);
 }