1 files changed, 90 insertions, 20 deletions

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 217581469f79..7a80f710ba2d 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -404,9 +404,16 @@ struct arm_smmu_cfg {
 #define ARM_SMMU_CB_ASID(cfg)           ((cfg)->cbndx)
 #define ARM_SMMU_CB_VMID(cfg)           ((cfg)->cbndx + 1)
 
+enum arm_smmu_domain_stage {
+        ARM_SMMU_DOMAIN_S1 = 0,
+        ARM_SMMU_DOMAIN_S2,
+        ARM_SMMU_DOMAIN_NESTED,
+};
+
 struct arm_smmu_domain {
         struct arm_smmu_device          *smmu;
         struct arm_smmu_cfg             cfg;
+        enum arm_smmu_domain_stage      stage;
         spinlock_t                      lock;
 };
 
@@ -906,19 +913,46 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
         if (smmu_domain->smmu)
                 goto out_unlock;
 
-        if (smmu->features & ARM_SMMU_FEAT_TRANS_NESTED) {
+        /*
+         * Mapping the requested stage onto what we support is surprisingly
+         * complicated, mainly because the spec allows S1+S2 SMMUs without
+         * support for nested translation. That means we end up with the
+         * following table:
+         *
+         * Requested        Supported        Actual
+         *     S1               N              S1
+         *     S1             S1+S2            S1
+         *     S1               S2             S2
+         *     S1               S1             S1
+         *     N                N              N
+         *     N              S1+S2            S2
+         *     N                S2             S2
+         *     N                S1             S1
+         *
+         * Note that you can't actually request stage-2 mappings.
+         */
+        if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1))
+                smmu_domain->stage = ARM_SMMU_DOMAIN_S2;
+        if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S2))
+                smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
+
+        switch (smmu_domain->stage) {
+        case ARM_SMMU_DOMAIN_S1:
+                cfg->cbar = CBAR_TYPE_S1_TRANS_S2_BYPASS;
+                start = smmu->num_s2_context_banks;
+                break;
+        case ARM_SMMU_DOMAIN_NESTED:
                 /*
                  * We will likely want to change this if/when KVM gets
                  * involved.
                  */
-                cfg->cbar = CBAR_TYPE_S1_TRANS_S2_BYPASS;
-                start = smmu->num_s2_context_banks;
-        } else if (smmu->features & ARM_SMMU_FEAT_TRANS_S1) {
-                cfg->cbar = CBAR_TYPE_S1_TRANS_S2_BYPASS;
-                start = smmu->num_s2_context_banks;
-        } else {
+        case ARM_SMMU_DOMAIN_S2:
                 cfg->cbar = CBAR_TYPE_S2_TRANS;
                 start = 0;
+                break;
+        default:
+                ret = -EINVAL;
+                goto out_unlock;
         }
 
         ret = __arm_smmu_alloc_bitmap(smmu->context_map, start,
@@ -1647,20 +1681,56 @@ static void arm_smmu_remove_device(struct device *dev)
         iommu_group_remove_device(dev);
 }
 
+static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
+                                    enum iommu_attr attr, void *data)
+{
+        struct arm_smmu_domain *smmu_domain = domain->priv;
+
+        switch (attr) {
+        case DOMAIN_ATTR_NESTING:
+                *(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
+                return 0;
+        default:
+                return -ENODEV;
+        }
+}
+
+static int arm_smmu_domain_set_attr(struct iommu_domain *domain,
+                                    enum iommu_attr attr, void *data)
+{
+        struct arm_smmu_domain *smmu_domain = domain->priv;
+
+        switch (attr) {
+        case DOMAIN_ATTR_NESTING:
+                if (smmu_domain->smmu)
+                        return -EPERM;
+                if (*(int *)data)
+                        smmu_domain->stage = ARM_SMMU_DOMAIN_NESTED;
+                else
+                        smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
+
+                return 0;
+        default:
+                return -ENODEV;
+        }
+}
+
 static const struct iommu_ops arm_smmu_ops = {
-        .capable        = arm_smmu_capable,
-        .domain_init    = arm_smmu_domain_init,
-        .domain_destroy = arm_smmu_domain_destroy,
-        .attach_dev     = arm_smmu_attach_dev,
-        .detach_dev     = arm_smmu_detach_dev,
-        .map            = arm_smmu_map,
-        .unmap          = arm_smmu_unmap,
-        .iova_to_phys   = arm_smmu_iova_to_phys,
-        .add_device     = arm_smmu_add_device,
-        .remove_device  = arm_smmu_remove_device,
-        .pgsize_bitmap  = (SECTION_SIZE |
-                           ARM_SMMU_PTE_CONT_SIZE |
-                           PAGE_SIZE),
+        .capable                = arm_smmu_capable,
+        .domain_init            = arm_smmu_domain_init,
+        .domain_destroy         = arm_smmu_domain_destroy,
+        .attach_dev             = arm_smmu_attach_dev,
+        .detach_dev             = arm_smmu_detach_dev,
+        .map                    = arm_smmu_map,
+        .unmap                  = arm_smmu_unmap,
+        .iova_to_phys           = arm_smmu_iova_to_phys,
+        .add_device             = arm_smmu_add_device,
+        .remove_device          = arm_smmu_remove_device,
+        .domain_get_attr        = arm_smmu_domain_get_attr,
+        .domain_set_attr        = arm_smmu_domain_set_attr,
+        .pgsize_bitmap          = (SECTION_SIZE |
+                                   ARM_SMMU_PTE_CONT_SIZE |
+                                   PAGE_SIZE),
 };
 
 static void arm_smmu_device_reset(struct arm_smmu_device *smmu)