iommu/arm-smmu-v3: Add a global static IDENTITY domain

Move to the new static global for identity domains. Move all the logic out
of arm_smmu_attach_dev into an identity only function.

Reviewed-by: Michael Shavit <mshavit@google.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Moritz Fischer <moritzf@google.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/12-v6-96275f25c39d+2d4-smmuv3_newapi_p1_jgg@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>

Author: jgunthorpe

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2200,8 +2200,7 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
 		return arm_smmu_sva_domain_alloc();
 
 	if (type != IOMMU_DOMAIN_UNMANAGED &&
-	    type != IOMMU_DOMAIN_DMA &&
-	    type != IOMMU_DOMAIN_IDENTITY)
+	    type != IOMMU_DOMAIN_DMA)
 		return NULL;
 
 	/*
@@ -2309,11 +2308,6 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain)
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 
-	if (domain->type == IOMMU_DOMAIN_IDENTITY) {
-		smmu_domain->stage = ARM_SMMU_DOMAIN_BYPASS;
-		return 0;
-	}
-
 	/* Restrict the stage to what we can actually support */
 	if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1))
 		smmu_domain->stage = ARM_SMMU_DOMAIN_S2;
@@ -2511,7 +2505,7 @@ static void arm_smmu_detach_dev(struct arm_smmu_master *master)
 	struct arm_smmu_domain *smmu_domain;
 	unsigned long flags;
 
-	if (!domain)
+	if (!domain || !(domain->type & __IOMMU_DOMAIN_PAGING))
 		return;
 
 	smmu_domain = to_smmu_domain(domain);
@@ -2574,15 +2568,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 
 	arm_smmu_detach_dev(master);
 
-	/*
-	 * The SMMU does not support enabling ATS with bypass. When the STE is
-	 * in bypass (STE.Config[2:0] == 0b100), ATS Translation Requests and
-	 * Translated transactions are denied as though ATS is disabled for the
-	 * stream (STE.EATS == 0b00), causing F_BAD_ATS_TREQ and
-	 * F_TRANSL_FORBIDDEN events (IHI0070Ea 5.2 Stream Table Entry).
-	 */
-	if (smmu_domain->stage != ARM_SMMU_DOMAIN_BYPASS)
-		master->ats_enabled = arm_smmu_ats_supported(master);
+	master->ats_enabled = arm_smmu_ats_supported(master);
 
 	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
 	list_add(&master->domain_head, &smmu_domain->devices);
@@ -2619,13 +2605,6 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 			arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID,
 						      NULL);
 		break;
-	case ARM_SMMU_DOMAIN_BYPASS:
-		arm_smmu_make_bypass_ste(&target);
-		arm_smmu_install_ste_for_dev(master, &target);
-		if (master->cd_table.cdtab)
-			arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID,
-						      NULL);
-		break;
 	}
 
 	arm_smmu_enable_ats(master, smmu_domain);
@@ -2641,6 +2620,60 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	return ret;
 }
 
+static int arm_smmu_attach_dev_ste(struct device *dev,
+				   struct arm_smmu_ste *ste)
+{
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
+	if (arm_smmu_master_sva_enabled(master))
+		return -EBUSY;
+
+	/*
+	 * Do not allow any ASID to be changed while are working on the STE,
+	 * otherwise we could miss invalidations.
+	 */
+	mutex_lock(&arm_smmu_asid_lock);
+
+	/*
+	 * The SMMU does not support enabling ATS with bypass/abort. When the
+	 * STE is in bypass (STE.Config[2:0] == 0b100), ATS Translation Requests
+	 * and Translated transactions are denied as though ATS is disabled for
+	 * the stream (STE.EATS == 0b00), causing F_BAD_ATS_TREQ and
+	 * F_TRANSL_FORBIDDEN events (IHI0070Ea 5.2 Stream Table Entry).
+	 */
+	arm_smmu_detach_dev(master);
+
+	arm_smmu_install_ste_for_dev(master, ste);
+	mutex_unlock(&arm_smmu_asid_lock);
+
+	/*
+	 * This has to be done after removing the master from the
+	 * arm_smmu_domain->devices to avoid races updating the same context
+	 * descriptor from arm_smmu_share_asid().
+	 */
+	if (master->cd_table.cdtab)
+		arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID, NULL);
+	return 0;
+}
+
+static int arm_smmu_attach_dev_identity(struct iommu_domain *domain,
+					struct device *dev)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_make_bypass_ste(&ste);
+	return arm_smmu_attach_dev_ste(dev, &ste);
+}
+
+static const struct iommu_domain_ops arm_smmu_identity_ops = {
+	.attach_dev = arm_smmu_attach_dev_identity,
+};
+
+static struct iommu_domain arm_smmu_identity_domain = {
+	.type = IOMMU_DOMAIN_IDENTITY,
+	.ops = &arm_smmu_identity_ops,
+};
+
 static int arm_smmu_map_pages(struct iommu_domain *domain, unsigned long iova,
 			      phys_addr_t paddr, size_t pgsize, size_t pgcount,
 			      int prot, gfp_t gfp, size_t *mapped)
@@ -3030,6 +3063,7 @@ static void arm_smmu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
 }
 
 static struct iommu_ops arm_smmu_ops = {
+	.identity_domain	= &arm_smmu_identity_domain,
 	.capable		= arm_smmu_capable,
 	.domain_alloc		= arm_smmu_domain_alloc,
 	.probe_device		= arm_smmu_probe_device,

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

@@ -712,7 +712,6 @@ struct arm_smmu_master {
 enum arm_smmu_domain_stage {
 	ARM_SMMU_DOMAIN_S1 = 0,
 	ARM_SMMU_DOMAIN_S2,
-	ARM_SMMU_DOMAIN_BYPASS,
 };
 
 struct arm_smmu_domain {