[PATCH v2 09/18] iommu/arm-smmu-v3: Implement set_dev_pasid

[Michael Shavit <mshavit@google.com>]

This change enables the use of the iommu_attach_dev_pasid API for
UNMANAGED domains. The primary use-case is to allow in-kernel users of
the iommu API to manage domains with PASID. This change also allows for
future support of pasid in the DMA api.

Signed-off-by: Michael Shavit <mshavit@google.com>
---
v1->v2: Add missing atc invalidation when detaching with pasid
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 168 +++++++++++++++++---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |   1 +
 2 files changed, 149 insertions(+), 20 deletions(-)

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 176013bb974b8..a6fa56585c219 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2173,6 +2173,10 @@ static int arm_smmu_domain_finalise_s2(struct arm_smmu_domain *smmu_domain,
 	return 0;
 }
 
+/*
+ * master may be null for domain types that are finalized before being attached
+ * to a master.
+ */
 static int arm_smmu_domain_finalise(struct iommu_domain *domain,
 				    struct arm_smmu_master *master)
 {
@@ -2369,6 +2373,11 @@ static int arm_smmu_enable_pasid(struct arm_smmu_master *master)
 	return 0;
 }
 
+static bool arm_smmu_master_has_pasid_domains(struct arm_smmu_master *master)
+{
+	return master->nr_attached_pasid_domains > 0;
+}
+
 static void arm_smmu_disable_pasid(struct arm_smmu_master *master)
 {
 	struct pci_dev *pdev;
@@ -2411,6 +2420,28 @@ static void arm_smmu_detach_dev(struct arm_smmu_master *master)
 	arm_smmu_install_ste_for_dev(master);
 }
 
+/*
+ * Once attached for the first time, a domain can no longer be attached to any
+ * master with a distinct upstream SMMU.
+ */
+static int arm_smmu_prepare_domain_for_smmu(struct arm_smmu_device *smmu,
+					    struct arm_smmu_domain *smmu_domain)
+{
+	int ret = 0;
+
+	mutex_lock(&smmu_domain->init_mutex);
+	if (!smmu_domain->smmu) {
+		smmu_domain->smmu = smmu;
+		ret = arm_smmu_domain_finalise(&smmu_domain->domain, NULL);
+		if (ret)
+			smmu_domain->smmu = NULL;
+	} else if (smmu_domain->smmu != smmu) {
+		ret = -EINVAL;
+	}
+	mutex_unlock(&smmu_domain->init_mutex);
+	return ret;
+}
+
 static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 {
 	int ret = 0;
@@ -2426,6 +2457,10 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	master = dev_iommu_priv_get(dev);
 	smmu = master->smmu;
 
+	ret = arm_smmu_prepare_domain_for_smmu(smmu, smmu_domain);
+	if (ret)
+		return ret;
+
 	/*
 	 * Checking that SVA is disabled ensures that this device isn't bound to
 	 * any mm, and can be safely detached from its old domain. Bonds cannot
@@ -2436,22 +2471,18 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 		return -EBUSY;
 	}
 
-	arm_smmu_detach_dev(master);
-
-	mutex_lock(&smmu_domain->init_mutex);
-
-	if (!smmu_domain->smmu) {
-		smmu_domain->smmu = smmu;
-		ret = arm_smmu_domain_finalise(domain, master);
-		if (ret) {
-			smmu_domain->smmu = NULL;
-			goto out_unlock;
-		}
-	} else if (smmu_domain->smmu != smmu) {
-		ret = -EINVAL;
-		goto out_unlock;
+	/*
+	 * Attaching a bypass or stage 2 domain would break any domains attached
+	 * with pasid. Attaching an S1 domain should be feasible but requires
+	 * more complicated logic to handle.
+	 */
+	if (arm_smmu_master_has_pasid_domains(master)) {
+		dev_err(dev, "cannot attach - domain attached with pasid\n");
+		return -EBUSY;
 	}
 
+	arm_smmu_detach_dev(master);
+
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
 		master->s1_cfg = &master->owned_s1_cfg;
 		ret = arm_smmu_write_ctx_desc(
@@ -2460,8 +2491,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 			0, &smmu_domain->cd);
 		if (ret) {
 			master->s1_cfg = NULL;
-			master->domain = NULL;
-			goto out_unlock;
+			return ret;
 		}
 	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S2 ||
 		   smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED) {
@@ -2490,11 +2520,75 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 
 	arm_smmu_enable_ats(master, smmu_domain);
 
-out_unlock:
-	mutex_unlock(&smmu_domain->init_mutex);
 	return ret;
 }
 
+static int arm_smmu_set_dev_pasid(struct iommu_domain *domain,
+				  struct device *dev, ioasid_t pasid)
+{
+	int ret = 0;
+	unsigned long flags;
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct arm_smmu_device *smmu;
+	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+	struct arm_smmu_attached_domain *attached_domain;
+	struct arm_smmu_master *master;
+
+	if (!fwspec)
+		return -ENOENT;
+
+	master = dev_iommu_priv_get(dev);
+	smmu = master->smmu;
+
+	ret = arm_smmu_prepare_domain_for_smmu(smmu, smmu_domain);
+	if (ret)
+		return ret;
+
+	if (pasid == 0) {
+		dev_err(dev, "pasid 0 is reserved for the device's primary domain\n");
+		return -ENODEV;
+	}
+
+	if (smmu_domain->stage != ARM_SMMU_DOMAIN_S1) {
+		dev_err(dev, "set_dev_pasid only supports stage 1 domains\n");
+		return -EINVAL;
+	}
+
+	if (!master->s1_cfg || master->s2_cfg)
+		return -EBUSY;
+
+	attached_domain = kzalloc(sizeof(*attached_domain), GFP_KERNEL);
+	if (!attached_domain)
+		return -ENOMEM;
+
+	attached_domain->master = master;
+	attached_domain->domain = smmu_domain;
+	attached_domain->ssid = pasid;
+
+	master->nr_attached_pasid_domains += 1;
+	/*
+	 * arm_smmu_share_asid may update the cd's asid value and write the
+	 * ctx_desc for every attached_domains in the list. There's a potential
+	 * race here regardless of whether we first write the ctx_desc or
+	 * first insert into the domain's list. Grabbing the asic_lock prevents
+	 * SVA from changing the cd's ASID while the cd is being attached.
+	 */
+	mutex_lock(&arm_smmu_asid_lock);
+	ret = arm_smmu_write_ctx_desc(master->smmu, master->s1_cfg, master,
+				      pasid, &smmu_domain->cd);
+	if (ret) {
+		mutex_unlock(&arm_smmu_asid_lock);
+		kfree(attached_domain);
+	}
+
+	spin_lock_irqsave(&smmu_domain->attached_domains_lock, flags);
+	list_add(&attached_domain->domain_head, &smmu_domain->attached_domains);
+	spin_unlock_irqrestore(&smmu_domain->attached_domains_lock, flags);
+	mutex_unlock(&arm_smmu_asid_lock);
+
+	return 0;
+}
+
 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)
@@ -2740,6 +2834,15 @@ static void arm_smmu_release_device(struct device *dev)
 
 	if (WARN_ON(arm_smmu_master_sva_enabled(master)))
 		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
+	if (WARN_ON(master->nr_attached_pasid_domains != 0)) {
+		/*
+		 * TODO: Do we need to handle this case?
+		 * This requires a mechanism to obtain all the pasid domains
+		 * that this master is attached to so that we can clean up the
+		 * domain's attached_domain list.
+		 */
+	}
+
 	arm_smmu_detach_dev(master);
 	arm_smmu_free_cd_tables(master->smmu, &master->owned_s1_cfg.cdcfg);
 	arm_smmu_disable_pasid(master);
@@ -2875,12 +2978,36 @@ static int arm_smmu_def_domain_type(struct device *dev)
 static void arm_smmu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
 {
 	struct iommu_domain *domain;
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+	struct arm_smmu_domain *smmu_domain;
+	struct arm_smmu_attached_domain *attached_domain;
+	unsigned long flags;
 
-	domain = iommu_get_domain_for_dev_pasid(dev, pasid, IOMMU_DOMAIN_SVA);
+	if (!master || pasid == 0)
+		return;
+
+	domain = iommu_get_domain_for_dev_pasid(dev, pasid, 0);
 	if (WARN_ON(IS_ERR(domain)) || !domain)
 		return;
+	if (domain->type == IOMMU_DOMAIN_SVA)
+		return arm_smmu_sva_remove_dev_pasid(domain, dev, pasid);
 
-	arm_smmu_sva_remove_dev_pasid(domain, dev, pasid);
+	smmu_domain = to_smmu_domain(domain);
+	mutex_lock(&arm_smmu_asid_lock);
+	spin_lock_irqsave(&smmu_domain->attached_domains_lock, flags);
+	list_for_each_entry(attached_domain, &smmu_domain->attached_domains, domain_head) {
+		if (attached_domain->master != master ||
+		    attached_domain->ssid != pasid)
+			continue;
+		list_del(&attached_domain->domain_head);
+		break;
+	}
+	spin_unlock_irqrestore(&smmu_domain->attached_domains_lock, flags);
+	arm_smmu_write_ctx_desc(master->smmu, master->s1_cfg, master, pasid,
+				NULL);
+	arm_smmu_atc_inv_master_ssid(master, pasid);
+	master->nr_attached_pasid_domains -= 1;
+	mutex_unlock(&arm_smmu_asid_lock);
 }
 
 static struct iommu_ops arm_smmu_ops = {
@@ -2900,6 +3027,7 @@ static struct iommu_ops arm_smmu_ops = {
 	.owner			= THIS_MODULE,
 	.default_domain_ops = &(const struct iommu_domain_ops) {
 		.attach_dev		= arm_smmu_attach_dev,
+		.set_dev_pasid		= arm_smmu_set_dev_pasid,
 		.map_pages		= arm_smmu_map_pages,
 		.unmap_pages		= arm_smmu_unmap_pages,
 		.flush_iotlb_all	= arm_smmu_flush_iotlb_all,
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 6929590530367..48795a7287b69 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -707,6 +707,7 @@ struct arm_smmu_master {
 	bool				iopf_enabled;
 	struct list_head		bonds;
 	unsigned int			ssid_bits;
+	unsigned int			nr_attached_pasid_domains;
 };
 
 /* SMMU private data for an IOMMU domain */
-- 
2.41.0.rc0.172.g3f132b7071-goog