(dev, pasid);
 }
diff --git a/drivers/iommu/intel/pasid.h b/drivers/iommu/intel/pasid.h
index a771a77d4239c..637373995be80 100644
--- a/drivers/iommu/intel/pasid.h
+++ b/drivers/iommu/intel/pasid.h
@@ -233,9 +233,23 @@ static inline void pasid_set_wpe(struct pasid_entry *pe)
  */
 static inline void pasid_set_present(struct pasid_entry *pe)
 {
+	dma_wmb();
 	pasid_set_bits(&pe->val[0], 1 << 0, 1);
 }
 
+/*
+ * Clear the Present (P) bit (bit 0) of a scalable-mode PASID table entry.
+ * This initiates the transition of the entry's ownership from hardware
+ * to software. The caller is responsible for fulfilling the invalidation
+ * handshake recommended by the VT-d spec, Section 6.5.3.3 (Guidance to
+ * Software for Invalidations).
+ */
+static inline void pasid_clear_present(struct pasid_entry *pe)
+{
+	pasid_set_bits(&pe->val[0], 1 << 0, 0);
+	dma_wmb();
+}
+
 /*
  * Setup Page Walk Snoop bit (Bit 87) of a scalable mode PASID
  * entry.
-- 
2.51.0[PATCH 6.18 267/641] iommu/vt-d: Clear Present bit before tearing down PASID entryGreg Kroah-Hartman <gregkh@linuxfoundation.org> undefinedstable@vger.kernel.org undefined undefined undefined undefined undefined undefined undefined undefined¹K†•&