Add a new driver-type for ARM SMMUv3 to enum iommu_viommu_type. Implement
an arm_vsmmu_alloc() with its viommu op arm_vsmmu_domain_alloc_nested(),
to replace arm_smmu_domain_alloc_nesting(). As an initial step, copy the
VMID from s2_parent. A later cleanup series is required to move the VMID
allocation out of the stage-2 domain allocation routine to this.

After that, replace nested_domain->s2_parent with nested_domain->vsmmu.

Note that the validatting conditions for a nested_domain allocation are
moved from arm_vsmmu_domain_alloc_nested to arm_vsmmu_alloc, since there
is no point in creating a vIOMMU (vsmmu) from the beginning if it would
not support a nested_domain.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   | 26 +++---
 include/uapi/linux/iommufd.h                  |  2 +
 .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c     | 80 ++++++++++++-------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |  9 +--
 4 files changed, 71 insertions(+), 46 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index 956c12637866..5a025d310dbe 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -10,6 +10,7 @@
 
 #include <linux/bitfield.h>
 #include <linux/iommu.h>
+#include <linux/iommufd.h>
 #include <linux/kernel.h>
 #include <linux/mmzone.h>
 #include <linux/sizes.h>
@@ -835,7 +836,7 @@ struct arm_smmu_domain {
 
 struct arm_smmu_nested_domain {
 	struct iommu_domain domain;
-	struct arm_smmu_domain *s2_parent;
+	struct arm_vsmmu *vsmmu;
 
 	__le64 ste[2];
 };
@@ -1005,21 +1006,22 @@ tegra241_cmdqv_probe(struct arm_smmu_device *smmu)
 }
 #endif /* CONFIG_TEGRA241_CMDQV */
 
+struct arm_vsmmu {
+	struct iommufd_viommu core;
+	struct arm_smmu_device *smmu;
+	struct arm_smmu_domain *s2_parent;
+	u16 vmid;
+};
+
 #if IS_ENABLED(CONFIG_ARM_SMMU_V3_IOMMUFD)
 void *arm_smmu_hw_info(struct device *dev, u32 *length, u32 *type);
-struct iommu_domain *
-arm_smmu_domain_alloc_nesting(struct device *dev, u32 flags,
-			      struct iommu_domain *parent,
-			      const struct iommu_user_data *user_data);
+struct iommufd_viommu *arm_vsmmu_alloc(struct device *dev,
+				       struct iommu_domain *parent,
+				       struct iommufd_ctx *ictx,
+				       unsigned int viommu_type);
 #else
 #define arm_smmu_hw_info NULL
-static inline struct iommu_domain *
-arm_smmu_domain_alloc_nesting(struct device *dev, u32 flags,
-			      struct iommu_domain *parent,
-			      const struct iommu_user_data *user_data)
-{
-	return ERR_PTR(-EOPNOTSUPP);
-}
+#define arm_vsmmu_alloc NULL
 #endif /* CONFIG_ARM_SMMU_V3_IOMMUFD */
 
 #endif /* _ARM_SMMU_V3_H */
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 717659b9fdce..56c742106a45 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -859,9 +859,11 @@ struct iommu_fault_alloc {
 /**
  * enum iommu_viommu_type - Virtual IOMMU Type
  * @IOMMU_VIOMMU_TYPE_DEFAULT: Reserved for future use
+ * @IOMMU_VIOMMU_TYPE_ARM_SMMUV3: ARM SMMUv3 driver specific type
  */
 enum iommu_viommu_type {
 	IOMMU_VIOMMU_TYPE_DEFAULT = 0,
+	IOMMU_VIOMMU_TYPE_ARM_SMMUV3 = 1,
 };
 
 /**
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
index 44e1b9bef850..abb6d2868376 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
@@ -34,7 +34,8 @@ static void arm_smmu_make_nested_cd_table_ste(
 	struct arm_smmu_ste *target, struct arm_smmu_master *master,
 	struct arm_smmu_nested_domain *nested_domain, bool ats_enabled)
 {
-	arm_smmu_make_s2_domain_ste(target, master, nested_domain->s2_parent,
+	arm_smmu_make_s2_domain_ste(target, master,
+				    nested_domain->vsmmu->s2_parent,
 				    ats_enabled);
 
 	target->data[0] = cpu_to_le64(STRTAB_STE_0_V |
@@ -75,7 +76,8 @@ static void arm_smmu_make_nested_domain_ste(
 		break;
 	case STRTAB_STE_0_CFG_BYPASS:
 		arm_smmu_make_s2_domain_ste(
-			target, master, nested_domain->s2_parent, ats_enabled);
+			target, master, nested_domain->vsmmu->s2_parent,
+			ats_enabled);
 		break;
 	case STRTAB_STE_0_CFG_ABORT:
 	default:
@@ -100,7 +102,7 @@ static int arm_smmu_attach_dev_nested(struct iommu_domain *domain,
 	struct arm_smmu_ste ste;
 	int ret;
 
-	if (nested_domain->s2_parent->smmu != master->smmu)
+	if (nested_domain->vsmmu->smmu != master->smmu)
 		return -EINVAL;
 	if (arm_smmu_ssids_in_use(&master->cd_table))
 		return -EBUSY;
@@ -151,36 +153,15 @@ static int arm_smmu_validate_vste(struct iommu_hwpt_arm_smmuv3 *arg)
 	return 0;
 }
 
-struct iommu_domain *
-arm_smmu_domain_alloc_nesting(struct device *dev, u32 flags,
-			      struct iommu_domain *parent,
+static struct iommu_domain *
+arm_vsmmu_alloc_domain_nested(struct iommufd_viommu *viommu,
 			      const struct iommu_user_data *user_data)
 {
-	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+	struct arm_vsmmu *vsmmu = container_of(viommu, struct arm_vsmmu, core);
 	struct arm_smmu_nested_domain *nested_domain;
-	struct arm_smmu_domain *smmu_parent;
 	struct iommu_hwpt_arm_smmuv3 arg;
 	int ret;
 
-	if (flags || !(master->smmu->features & ARM_SMMU_FEAT_NESTING))
-		return ERR_PTR(-EOPNOTSUPP);
-
-	/*
-	 * Must support some way to prevent the VM from bypassing the cache
-	 * because VFIO currently does not do any cache maintenance.
-	 */
-	if (!arm_smmu_master_canwbs(master) &&
-	    !(master->smmu->features & ARM_SMMU_FEAT_S2FWB))
-		return ERR_PTR(-EOPNOTSUPP);
-
-	/*
-	 * The core code checks that parent was created with
-	 * IOMMU_HWPT_ALLOC_NEST_PARENT
-	 */
-	smmu_parent = to_smmu_domain(parent);
-	if (smmu_parent->smmu != master->smmu)
-		return ERR_PTR(-EINVAL);
-
 	ret = iommu_copy_struct_from_user(&arg, user_data,
 					  IOMMU_HWPT_DATA_ARM_SMMUV3, ste);
 	if (ret)
@@ -196,9 +177,52 @@ arm_smmu_domain_alloc_nesting(struct device *dev, u32 flags,
 
 	nested_domain->domain.type = IOMMU_DOMAIN_NESTED;
 	nested_domain->domain.ops = &arm_smmu_nested_ops;
-	nested_domain->s2_parent = smmu_parent;
+	nested_domain->vsmmu = vsmmu;
 	nested_domain->ste[0] = arg.ste[0];
 	nested_domain->ste[1] = arg.ste[1] & ~cpu_to_le64(STRTAB_STE_1_EATS);
 
 	return &nested_domain->domain;
 }
+
+
+static const struct iommufd_viommu_ops arm_vsmmu_ops = {
+	.alloc_domain_nested = arm_vsmmu_alloc_domain_nested,
+};
+
+struct iommufd_viommu *arm_vsmmu_alloc(struct device *dev,
+				       struct iommu_domain *parent,
+				       struct iommufd_ctx *ictx,
+				       unsigned int viommu_type)
+{
+	struct arm_smmu_device *smmu =
+		iommu_get_iommu_dev(dev, struct arm_smmu_device, iommu);
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+	struct arm_smmu_domain *s2_parent = to_smmu_domain(parent);
+	struct arm_vsmmu *vsmmu;
+
+	if (viommu_type != IOMMU_VIOMMU_TYPE_ARM_SMMUV3)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	if (!(smmu->features & ARM_SMMU_FEAT_NESTING))
+		return ERR_PTR(-EOPNOTSUPP);
+
+	/*
+	 * Must support some way to prevent the VM from bypassing the cache
+	 * because VFIO currently does not do any cache maintenance.
+	 */
+	if (!arm_smmu_master_canwbs(master) &&
+	    !(smmu->features & ARM_SMMU_FEAT_S2FWB))
+		return ERR_PTR(-EOPNOTSUPP);
+
+	vsmmu = iommufd_viommu_alloc(ictx, struct arm_vsmmu, core,
+				     &arm_vsmmu_ops);
+	if (IS_ERR(vsmmu))
+		return ERR_CAST(vsmmu);
+
+	vsmmu->smmu = smmu;
+	vsmmu->s2_parent = s2_parent;
+	/* FIXME Move VMID allocation from the S2 domain allocation to here */
+	vsmmu->vmid = s2_parent->s2_cfg.vmid;
+
+	return &vsmmu->core;
+}
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 0d79a1bd9049..8215c49d3bac 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2661,7 +2661,7 @@ to_smmu_domain_devices(struct iommu_domain *domain)
 	    domain->type == IOMMU_DOMAIN_SVA)
 		return to_smmu_domain(domain);
 	if (domain->type == IOMMU_DOMAIN_NESTED)
-		return to_smmu_nested_domain(domain)->s2_parent;
+		return to_smmu_nested_domain(domain)->vsmmu->s2_parent;
 	return NULL;
 }
 
@@ -3126,13 +3126,9 @@ arm_smmu_domain_alloc_user(struct device *dev, u32 flags,
 	struct arm_smmu_domain *smmu_domain;
 	int ret;
 
-	if (parent)
-		return arm_smmu_domain_alloc_nesting(dev, flags, parent,
-						     user_data);
-
 	if (flags & ~PAGING_FLAGS)
 		return ERR_PTR(-EOPNOTSUPP);
-	if (user_data)
+	if (parent || user_data)
 		return ERR_PTR(-EOPNOTSUPP);
 
 	smmu_domain = arm_smmu_domain_alloc();
@@ -3541,6 +3537,7 @@ static struct iommu_ops arm_smmu_ops = {
 	.dev_disable_feat	= arm_smmu_dev_disable_feature,
 	.page_response		= arm_smmu_page_response,
 	.def_domain_type	= arm_smmu_def_domain_type,
+	.viommu_alloc		= arm_vsmmu_alloc,
 	.user_pasid_table	= 1,
 	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
 	.owner			= THIS_MODULE,
-- 
2.43.0

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Saturday, October 26, 2024 7:50 AM
> 
> Add a new driver-type for ARM SMMUv3 to enum iommu_viommu_type.
> Implement
> an arm_vsmmu_alloc() with its viommu op
> arm_vsmmu_domain_alloc_nested(),
> to replace arm_smmu_domain_alloc_nesting(). As an initial step, copy the
> VMID from s2_parent. A later cleanup series is required to move the VMID
> allocation out of the stage-2 domain allocation routine to this.
> 
> After that, replace nested_domain->s2_parent with nested_domain->vsmmu.
> 
> Note that the validatting conditions for a nested_domain allocation are
> moved from arm_vsmmu_domain_alloc_nested to arm_vsmmu_alloc, since
> there
> is no point in creating a vIOMMU (vsmmu) from the beginning if it would
> not support a nested_domain.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Reviewed-by: Kevin Tian <kevin.tian@intel.com>