1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index d06a6d9edbca..bf4959f4225b 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1020,6 +1020,34 @@ static void amd_iommu_erratum_746_workaround(struct amd_iommu *iommu)
 }
 
 /*
+ * Family15h Model 30h-3fh (IOMMU Mishandles ATS Write Permission)
+ * Workaround:
+ *     BIOS should enable ATS write permission check by setting
+ *     L2_DEBUG_3[AtsIgnoreIWDis](D0F2xF4_x47[0]) = 1b
+ */
+static void amd_iommu_ats_write_check_workaround(struct amd_iommu *iommu)
+{
+        u32 value;
+
+        if ((boot_cpu_data.x86 != 0x15) ||
+            (boot_cpu_data.x86_model < 0x30) ||
+            (boot_cpu_data.x86_model > 0x3f))
+                return;
+
+        /* Test L2_DEBUG_3[AtsIgnoreIWDis] == 1 */
+        value = iommu_read_l2(iommu, 0x47);
+
+        if (value & BIT(0))
+                return;
+
+        /* Set L2_DEBUG_3[AtsIgnoreIWDis] = 1 */
+        iommu_write_l2(iommu, 0x47, value | BIT(0));
+
+        pr_info("AMD-Vi: Applying ATS write check workaround for IOMMU at %s\n",
+                dev_name(&iommu->dev->dev));
+}
+
+/*
  * This function clues the initialization function for one IOMMU
  * together and also allocates the command buffer and programs the
  * hardware. It does NOT enable the IOMMU. This is done afterwards.
@@ -1288,6 +1316,7 @@ static int iommu_init_pci(struct amd_iommu *iommu)
         }
 
         amd_iommu_erratum_746_workaround(iommu);
+        amd_iommu_ats_write_check_workaround(iommu);
 
         iommu->iommu_dev = iommu_device_create(&iommu->dev->dev, iommu,
                                                amd_iommu_groups, "ivhd%d",