1 files changed, 23 insertions, 8 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 68d43beccb7e..5ecfaf29933a 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -422,6 +422,14 @@ static int dmar_map_gfx = 1;
 static int dmar_forcedac;
 static int intel_iommu_strict;
 static int intel_iommu_superpage = 1;
+static int intel_iommu_ecs = 1;
+
+/* We only actually use ECS when PASID support (on the new bit 40)
+ * is also advertised. Some early implementations — the ones with
+ * PASID support on bit 28 — have issues even when we *only* use
+ * extended root/context tables. */
+#define ecs_enabled(iommu) (intel_iommu_ecs && ecap_ecs(iommu->ecap) && \
+                            ecap_pasid(iommu->ecap))
 
 int intel_iommu_gfx_mapped;
 EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);
@@ -465,6 +473,10 @@ static int __init intel_iommu_setup(char *str)
                         printk(KERN_INFO
                                 "Intel-IOMMU: disable supported super page\n");
                         intel_iommu_superpage = 0;
+                } else if (!strncmp(str, "ecs_off", 7)) {
+                        printk(KERN_INFO
+                                "Intel-IOMMU: disable extended context table support\n");
+                        intel_iommu_ecs = 0;
                 }
 
                 str += strcspn(str, ",");
@@ -669,7 +681,7 @@ static inline struct context_entry *iommu_context_addr(struct intel_iommu *iommu
         struct context_entry *context;
         u64 *entry;
 
-        if (ecap_ecs(iommu->ecap)) {
+        if (ecs_enabled(iommu)) {
                 if (devfn >= 0x80) {
                         devfn -= 0x80;
                         entry = &root->hi;
@@ -696,6 +708,11 @@ static inline struct context_entry *iommu_context_addr(struct intel_iommu *iommu
         return &context[devfn];
 }
 
+static int iommu_dummy(struct device *dev)
+{
+        return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
+}
+
 static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn)
 {
         struct dmar_drhd_unit *drhd = NULL;
@@ -705,6 +722,9 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf
         u16 segment = 0;
         int i;
 
+        if (iommu_dummy(dev))
+                return NULL;
+
         if (dev_is_pci(dev)) {
                 pdev = to_pci_dev(dev);
                 segment = pci_domain_nr(pdev->bus);
@@ -798,7 +818,7 @@ static void free_context_table(struct intel_iommu *iommu)
                 if (context)
                         free_pgtable_page(context);
 
-                if (!ecap_ecs(iommu->ecap))
+                if (!ecs_enabled(iommu))
                         continue;
 
                 context = iommu_context_addr(iommu, i, 0x80, 0);
@@ -1133,7 +1153,7 @@ static void iommu_set_root_entry(struct intel_iommu *iommu)
         unsigned long flag;
 
         addr = virt_to_phys(iommu->root_entry);
-        if (ecap_ecs(iommu->ecap))
+        if (ecs_enabled(iommu))
                 addr |= DMA_RTADDR_RTT;
 
         raw_spin_lock_irqsave(&iommu->register_lock, flag);
@@ -2969,11 +2989,6 @@ static inline struct dmar_domain *get_valid_domain_for_dev(struct device *dev)
         return __get_valid_domain_for_dev(dev);
 }
 
-static int iommu_dummy(struct device *dev)
-{
-        return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
-}
-
 /* Check if the dev needs to go through non-identity map and unmap process.*/
 static int iommu_no_mapping(struct device *dev)
 {