[PATCH v2 1/1] Revert "iommu/vt-d: Gracefully handle DMAR units with no supported address widths"

[Andrea Righi]

BugLink: https://bugs.launchpad.net/bugs/1918590

This reverts commit 561ef22a7d396289a1c5a1d18057ccdf9bb59826.

It seems that this patch is addressing the problem correctly only with
kernels >4.4. For now it is probably safer to simply drop this patch and
revert this change in 4.4 to avoid introducing potential regressions.

Signed-off-by: Andrea Righi <andrea.righi at canonical.com>
---
 drivers/iommu/dmar.c | 45 ++++++++++++++------------------------------
 1 file changed, 14 insertions(+), 31 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 78174f2f9fafb..00169c9eb3eed 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1012,8 +1012,8 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
 {
 	struct intel_iommu *iommu;
 	u32 ver, sts;
-	int agaw = -1;
-	int msagaw = -1;
+	int agaw = 0;
+	int msagaw = 0;
 	int err;
 
 	if (!drhd->reg_base_addr) {
@@ -1038,28 +1038,17 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
 	}
 
 	err = -EINVAL;
-	if (cap_sagaw(iommu->cap) == 0) {
-		pr_info("%s: No supported address widths. Not attempting DMA translation.\n",
-			iommu->name);
-		drhd->ignored = 1;
+	agaw = iommu_calculate_agaw(iommu);
+	if (agaw < 0) {
+		pr_err("Cannot get a valid agaw for iommu (seq_id = %d)\n",
+			iommu->seq_id);
+		goto err_unmap;
 	}
-
-	if (!drhd->ignored) {
-		agaw = iommu_calculate_agaw(iommu);
-		if (agaw < 0) {
-			pr_err("Cannot get a valid agaw for iommu (seq_id = %d)\n",
-			       iommu->seq_id);
-			drhd->ignored = 1;
-		}
-	}
-	if (!drhd->ignored) {
-		msagaw = iommu_calculate_max_sagaw(iommu);
-		if (msagaw < 0) {
-			pr_err("Cannot get a valid max agaw for iommu (seq_id = %d)\n",
-			       iommu->seq_id);
-			drhd->ignored = 1;
-			agaw = -1;
-		}
+	msagaw = iommu_calculate_max_sagaw(iommu);
+	if (msagaw < 0) {
+		pr_err("Cannot get a valid max agaw for iommu (seq_id = %d)\n",
+			iommu->seq_id);
+		goto err_unmap;
 	}
 	iommu->agaw = agaw;
 	iommu->msagaw = msagaw;
@@ -1088,12 +1077,7 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
 
 	drhd->iommu = iommu;
 
-	/*
-	 * This is only for hotplug; at boot time intel_iommu_enabled won't
-	 * be set yet. When intel_iommu_init() runs, it registers the units
-	 * present at boot time, then sets intel_iommu_enabled.
-	 */
-	if (intel_iommu_enabled && !drhd->ignored)
+	if (intel_iommu_enabled)
 		iommu->iommu_dev = iommu_device_create(NULL, iommu,
 						       intel_iommu_groups,
 						       "%s", iommu->name);
@@ -1111,8 +1095,7 @@ error:
 
 static void free_iommu(struct intel_iommu *iommu)
 {
-	if (intel_iommu_enabled && iommu->iommu_dev)
-		iommu_device_destroy(iommu->iommu_dev);
+	iommu_device_destroy(iommu->iommu_dev);
 
 	if (iommu->irq) {
 		if (iommu->pr_irq) {
-- 
2.30.1