iommu/vt-d: Fix incomplete cache flush in intel_pasid_tear_down_entry()

This fixes improper iotlb invalidation in intel_pasid_tear_down_entry().
When a PASID was used as nested mode, released and reused, the following
error message will appear:

[  180.187556] Unexpected page request in Privilege Mode
[  180.187565] Unexpected page request in Privilege Mode
[  180.279933] Unexpected page request in Privilege Mode
[  180.279937] Unexpected page request in Privilege Mode

Per chapter 6.5.3.3 of VT-d spec 3.3, when tear down a pasid entry, the
software should use Domain selective IOTLB flush if the PGTT of the pasid
entry is SL only or Nested, while for the pasid entries whose PGTT is FL
only or PT using PASID-based IOTLB flush is enough.

Fixes: 2cd1311a ("iommu/vt-d: Add set domain DOMAIN_ATTR_NESTING attr")
Signed-off-by: Kumar Sanjay K <sanjay.k.kumar@intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Tested-by: Yi Sun <yi.y.sun@intel.com>
Link: https://lore.kernel.org/r/20210817042425.1784279-1-yi.l.liu@intel.comSigned-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210817124321.1517985-3-baolu.lu@linux.intel.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/pasid.c

@@ -511,7 +511,7 @@ void intel_pasid_tear_down_entry(struct intel_iommu *iommu, struct device *dev,
 				 u32 pasid, bool fault_ignore)
 {
 	struct pasid_entry *pte;
-	u16 did;
+	u16 did, pgtt;
 
 	pte = intel_pasid_get_entry(dev, pasid);
 	if (WARN_ON(!pte))
@@ -521,13 +521,19 @@ void intel_pasid_tear_down_entry(struct intel_iommu *iommu, struct device *dev,
 		return;
 
 	did = pasid_get_domain_id(pte);
+	pgtt = pasid_pte_get_pgtt(pte);
+
 	intel_pasid_clear_entry(dev, pasid, fault_ignore);
 
 	if (!ecap_coherent(iommu->ecap))
 		clflush_cache_range(pte, sizeof(*pte));
 
 	pasid_cache_invalidation_with_pasid(iommu, did, pasid);
-	qi_flush_piotlb(iommu, did, pasid, 0, -1, 0);
+
+	if (pgtt == PASID_ENTRY_PGTT_PT || pgtt == PASID_ENTRY_PGTT_FL_ONLY)
+		qi_flush_piotlb(iommu, did, pasid, 0, -1, 0);
+	else
+		iommu->flush.flush_iotlb(iommu, did, 0, 0, DMA_TLB_DSI_FLUSH);
 
 	/* Device IOTLB doesn't need to be flushed in caching mode. */
 	if (!cap_caching_mode(iommu->cap))

drivers/iommu/intel/pasid.h

@@ -99,6 +99,12 @@ static inline bool pasid_pte_is_present(struct pasid_entry *pte)
 	return READ_ONCE(pte->val[0]) & PASID_PTE_PRESENT;
 }
 
+/* Get PGTT field of a PASID table entry */
+static inline u16 pasid_pte_get_pgtt(struct pasid_entry *pte)
+{
+	return (u16)((READ_ONCE(pte->val[0]) >> 6) & 0x7);
+}
+
 extern unsigned int intel_pasid_max_id;
 int intel_pasid_alloc_table(struct device *dev);
 void intel_pasid_free_table(struct device *dev);