iommu/vt-d: Add a helper to flush cache for updating present pasid entry

Generalize the logic for flushing pasid-related cache upon changes to
bits other than SSADE and P which requires a different flow according
to VT-d spec.

No functional change is intended.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20241107122234.7424-3-yi.l.liu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: yiliu1765

drivers/iommu/intel/pasid.c

@@ -287,6 +287,39 @@ static void pasid_flush_caches(struct intel_iommu *iommu,
 	}
 }
 
+/*
+ * This function is supposed to be used after caller updates the fields
+ * except for the SSADE and P bit of a pasid table entry. It does the
+ * below:
+ * - Flush cacheline if needed
+ * - Flush the caches per Table 28 ”Guidance to Software for Invalidations“
+ *   of VT-d spec 5.0.
+ */
+static void intel_pasid_flush_present(struct intel_iommu *iommu,
+				      struct device *dev,
+				      u32 pasid, u16 did,
+				      struct pasid_entry *pte)
+{
+	if (!ecap_coherent(iommu->ecap))
+		clflush_cache_range(pte, sizeof(*pte));
+
+	/*
+	 * VT-d spec 5.0 table28 states guides for cache invalidation:
+	 *
+	 * - PASID-selective-within-Domain PASID-cache invalidation
+	 * - PASID-selective PASID-based IOTLB invalidation
+	 * - If (pasid is RID_PASID)
+	 *    - Global Device-TLB invalidation to affected functions
+	 *   Else
+	 *    - PASID-based Device-TLB invalidation (with S=1 and
+	 *      Addr[63:12]=0x7FFFFFFF_FFFFF) to affected functions
+	 */
+	pasid_cache_invalidation_with_pasid(iommu, did, pasid);
+	qi_flush_piotlb(iommu, did, pasid, 0, -1, 0);
+
+	devtlb_invalidation_with_pasid(iommu, dev, pasid);
+}
+
 /*
  * Set up the scalable mode pasid table entry for first only
  * translation type.
@@ -526,24 +559,7 @@ void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
 	did = pasid_get_domain_id(pte);
 	spin_unlock(&iommu->lock);
 
-	if (!ecap_coherent(iommu->ecap))
-		clflush_cache_range(pte, sizeof(*pte));
-
-	/*
-	 * VT-d spec 3.4 table23 states guides for cache invalidation:
-	 *
-	 * - PASID-selective-within-Domain PASID-cache invalidation
-	 * - PASID-selective PASID-based IOTLB invalidation
-	 * - If (pasid is RID_PASID)
-	 *    - Global Device-TLB invalidation to affected functions
-	 *   Else
-	 *    - PASID-based Device-TLB invalidation (with S=1 and
-	 *      Addr[63:12]=0x7FFFFFFF_FFFFF) to affected functions
-	 */
-	pasid_cache_invalidation_with_pasid(iommu, did, pasid);
-	qi_flush_piotlb(iommu, did, pasid, 0, -1, 0);
-
-	devtlb_invalidation_with_pasid(iommu, dev, pasid);
+	intel_pasid_flush_present(iommu, dev, pasid, did, pte);
 }
 
 /**