iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster

Use it to store all vSMMU-related data. The vsid (Virtual Stream ID) will
be the first use case. Since the vsid reader will be the eventq handler
that already holds a streams_mutex, reuse that to fence the vmaster too.

Also add a pair of arm_smmu_attach_prepare/commit_vmaster helpers to set
or unset the master->vmaster pointer. Put the helpers inside the existing
arm_smmu_attach_prepare/commit().

For identity/blocked ops that don't call arm_smmu_attach_prepare/commit(),
add a simpler arm_smmu_master_clear_vmaster helper to unset the vmaster.

Link: https://patch.msgid.link/r/a7f282e1a531279e25f06c651e95d56f6b120886.1741719725.git.nicolinc@nvidia.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

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

@@ -85,6 +85,47 @@ static void arm_smmu_make_nested_domain_ste(
 	}
 }
 
+int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state,
+				    struct arm_smmu_nested_domain *nested_domain)
+{
+	struct arm_smmu_vmaster *vmaster;
+	unsigned long vsid;
+	int ret;
+
+	iommu_group_mutex_assert(state->master->dev);
+
+	ret = iommufd_viommu_get_vdev_id(&nested_domain->vsmmu->core,
+					 state->master->dev, &vsid);
+	if (ret)
+		return ret;
+
+	vmaster = kzalloc(sizeof(*vmaster), GFP_KERNEL);
+	if (!vmaster)
+		return -ENOMEM;
+	vmaster->vsmmu = nested_domain->vsmmu;
+	vmaster->vsid = vsid;
+	state->vmaster = vmaster;
+
+	return 0;
+}
+
+void arm_smmu_attach_commit_vmaster(struct arm_smmu_attach_state *state)
+{
+	struct arm_smmu_master *master = state->master;
+
+	mutex_lock(&master->smmu->streams_mutex);
+	kfree(master->vmaster);
+	master->vmaster = state->vmaster;
+	mutex_unlock(&master->smmu->streams_mutex);
+}
+
+void arm_smmu_master_clear_vmaster(struct arm_smmu_master *master)
+{
+	struct arm_smmu_attach_state state = { .master = master };
+
+	arm_smmu_attach_commit_vmaster(&state);
+}
+
 static int arm_smmu_attach_dev_nested(struct iommu_domain *domain,
 				      struct device *dev)
 {

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

@@ -2803,6 +2803,7 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state,
 	struct arm_smmu_domain *smmu_domain =
 		to_smmu_domain_devices(new_domain);
 	unsigned long flags;
+	int ret;
 
 	/*
 	 * arm_smmu_share_asid() must not see two domains pointing to the same
@@ -2832,9 +2833,18 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state,
 	}
 
 	if (smmu_domain) {
+		if (new_domain->type == IOMMU_DOMAIN_NESTED) {
+			ret = arm_smmu_attach_prepare_vmaster(
+				state, to_smmu_nested_domain(new_domain));
+			if (ret)
+				return ret;
+		}
+
 		master_domain = kzalloc(sizeof(*master_domain), GFP_KERNEL);
-		if (!master_domain)
+		if (!master_domain) {
+			kfree(state->vmaster);
 			return -ENOMEM;
+		}
 		master_domain->master = master;
 		master_domain->ssid = state->ssid;
 		if (new_domain->type == IOMMU_DOMAIN_NESTED)
@@ -2861,6 +2871,7 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state,
 			spin_unlock_irqrestore(&smmu_domain->devices_lock,
 					       flags);
 			kfree(master_domain);
+			kfree(state->vmaster);
 			return -EINVAL;
 		}
 
@@ -2893,6 +2904,8 @@ void arm_smmu_attach_commit(struct arm_smmu_attach_state *state)
 
 	lockdep_assert_held(&arm_smmu_asid_lock);
 
+	arm_smmu_attach_commit_vmaster(state);
+
 	if (state->ats_enabled && !master->ats_enabled) {
 		arm_smmu_enable_ats(master);
 	} else if (state->ats_enabled && master->ats_enabled) {
@@ -3162,6 +3175,7 @@ static int arm_smmu_attach_dev_identity(struct iommu_domain *domain,
 	struct arm_smmu_ste ste;
 	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
 
+	arm_smmu_master_clear_vmaster(master);
 	arm_smmu_make_bypass_ste(master->smmu, &ste);
 	arm_smmu_attach_dev_ste(domain, dev, &ste, STRTAB_STE_1_S1DSS_BYPASS);
 	return 0;
@@ -3180,7 +3194,9 @@ static int arm_smmu_attach_dev_blocked(struct iommu_domain *domain,
 					struct device *dev)
 {
 	struct arm_smmu_ste ste;
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
 
+	arm_smmu_master_clear_vmaster(master);
 	arm_smmu_make_abort_ste(&ste);
 	arm_smmu_attach_dev_ste(domain, dev, &ste,
 				STRTAB_STE_1_S1DSS_TERMINATE);

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

@@ -799,6 +799,11 @@ struct arm_smmu_stream {
 	struct rb_node			node;
 };
 
+struct arm_smmu_vmaster {
+	struct arm_vsmmu		*vsmmu;
+	unsigned long			vsid;
+};
+
 struct arm_smmu_event {
 	u8				stall : 1,
 					ssv : 1,
@@ -824,6 +829,7 @@ struct arm_smmu_master {
 	struct arm_smmu_device		*smmu;
 	struct device			*dev;
 	struct arm_smmu_stream		*streams;
+	struct arm_smmu_vmaster		*vmaster; /* use smmu->streams_mutex */
 	/* Locked by the iommu core using the group mutex */
 	struct arm_smmu_ctx_desc_cfg	cd_table;
 	unsigned int			num_streams;
@@ -972,6 +978,7 @@ struct arm_smmu_attach_state {
 	bool disable_ats;
 	ioasid_t ssid;
 	/* Resulting state */
+	struct arm_smmu_vmaster *vmaster;
 	bool ats_enabled;
 };
 
@@ -1055,9 +1062,30 @@ struct iommufd_viommu *arm_vsmmu_alloc(struct device *dev,
 				       struct iommu_domain *parent,
 				       struct iommufd_ctx *ictx,
 				       unsigned int viommu_type);
+int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state,
+				    struct arm_smmu_nested_domain *nested_domain);
+void arm_smmu_attach_commit_vmaster(struct arm_smmu_attach_state *state);
+void arm_smmu_master_clear_vmaster(struct arm_smmu_master *master);
 #else
 #define arm_smmu_hw_info NULL
 #define arm_vsmmu_alloc NULL
+
+static inline int
+arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state,
+				struct arm_smmu_nested_domain *nested_domain)
+{
+	return 0;
+}
+
+static inline void
+arm_smmu_attach_commit_vmaster(struct arm_smmu_attach_state *state)
+{
+}
+
+static inline void
+arm_smmu_master_clear_vmaster(struct arm_smmu_master *master)
+{
+}
 #endif /* CONFIG_ARM_SMMU_V3_IOMMUFD */
 
 #endif /* _ARM_SMMU_V3_H */