iommu/arm-smmu-v3: Add SVA device feature

Implement the IOMMU device feature callbacks to support the SVA feature.
At the moment dev_has_feat() returns false since I/O Page Faults and BTM
aren't yet implemented.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20200918101852.582559-12-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>

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

@@ -10,6 +10,8 @@
 #include "arm-smmu-v3.h"
 #include "../../io-pgtable-arm.h"
 
+static DEFINE_MUTEX(sva_lock);
+
 /*
  * Check if the CPU ASID is available on the SMMU side. If a private context
  * descriptor is using it, try to replace it.
@@ -197,3 +199,50 @@ bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
 
 	return true;
 }
+
+static bool arm_smmu_iopf_supported(struct arm_smmu_master *master)
+{
+	return false;
+}
+
+bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
+{
+	if (!(master->smmu->features & ARM_SMMU_FEAT_SVA))
+		return false;
+
+	/* SSID and IOPF support are mandatory for the moment */
+	return master->ssid_bits && arm_smmu_iopf_supported(master);
+}
+
+bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
+{
+	bool enabled;
+
+	mutex_lock(&sva_lock);
+	enabled = master->sva_enabled;
+	mutex_unlock(&sva_lock);
+	return enabled;
+}
+
+int arm_smmu_master_enable_sva(struct arm_smmu_master *master)
+{
+	mutex_lock(&sva_lock);
+	master->sva_enabled = true;
+	mutex_unlock(&sva_lock);
+
+	return 0;
+}
+
+int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
+{
+	mutex_lock(&sva_lock);
+	if (!list_empty(&master->bonds)) {
+		dev_err(master->dev, "cannot disable SVA, device is bound\n");
+		mutex_unlock(&sva_lock);
+		return -EBUSY;
+	}
+	master->sva_enabled = false;
+	mutex_unlock(&sva_lock);
+
+	return 0;
+}

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

@@ -2176,6 +2176,16 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	master = dev_iommu_priv_get(dev);
 	smmu = master->smmu;
 
+	/*
+	 * 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
+	 * be removed concurrently since we're holding the group mutex.
+	 */
+	if (arm_smmu_master_sva_enabled(master)) {
+		dev_err(dev, "cannot attach - SVA enabled\n");
+		return -EBUSY;
+	}
+
 	arm_smmu_detach_dev(master);
 
 	mutex_lock(&smmu_domain->init_mutex);
@@ -2323,6 +2333,7 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 	master->smmu = smmu;
 	master->sids = fwspec->ids;
 	master->num_sids = fwspec->num_ids;
+	INIT_LIST_HEAD(&master->bonds);
 	dev_iommu_priv_set(dev, master);
 
 	/* Check the SIDs are in range of the SMMU and our stream table */
@@ -2375,6 +2386,7 @@ static void arm_smmu_release_device(struct device *dev)
 		return;
 
 	master = dev_iommu_priv_get(dev);
+	WARN_ON(arm_smmu_master_sva_enabled(master));
 	arm_smmu_detach_dev(master);
 	arm_smmu_disable_pasid(master);
 	kfree(master);
@@ -2492,6 +2504,69 @@ static void arm_smmu_get_resv_regions(struct device *dev,
 	iommu_dma_get_resv_regions(dev, head);
 }
 
+static bool arm_smmu_dev_has_feature(struct device *dev,
+				     enum iommu_dev_features feat)
+{
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
+	if (!master)
+		return false;
+
+	switch (feat) {
+	case IOMMU_DEV_FEAT_SVA:
+		return arm_smmu_master_sva_supported(master);
+	default:
+		return false;
+	}
+}
+
+static bool arm_smmu_dev_feature_enabled(struct device *dev,
+					 enum iommu_dev_features feat)
+{
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
+	if (!master)
+		return false;
+
+	switch (feat) {
+	case IOMMU_DEV_FEAT_SVA:
+		return arm_smmu_master_sva_enabled(master);
+	default:
+		return false;
+	}
+}
+
+static int arm_smmu_dev_enable_feature(struct device *dev,
+				       enum iommu_dev_features feat)
+{
+	if (!arm_smmu_dev_has_feature(dev, feat))
+		return -ENODEV;
+
+	if (arm_smmu_dev_feature_enabled(dev, feat))
+		return -EBUSY;
+
+	switch (feat) {
+	case IOMMU_DEV_FEAT_SVA:
+		return arm_smmu_master_enable_sva(dev_iommu_priv_get(dev));
+	default:
+		return -EINVAL;
+	}
+}
+
+static int arm_smmu_dev_disable_feature(struct device *dev,
+					enum iommu_dev_features feat)
+{
+	if (!arm_smmu_dev_feature_enabled(dev, feat))
+		return -EINVAL;
+
+	switch (feat) {
+	case IOMMU_DEV_FEAT_SVA:
+		return arm_smmu_master_disable_sva(dev_iommu_priv_get(dev));
+	default:
+		return -EINVAL;
+	}
+}
+
 static struct iommu_ops arm_smmu_ops = {
 	.capable		= arm_smmu_capable,
 	.domain_alloc		= arm_smmu_domain_alloc,
@@ -2510,6 +2585,10 @@ static struct iommu_ops arm_smmu_ops = {
 	.of_xlate		= arm_smmu_of_xlate,
 	.get_resv_regions	= arm_smmu_get_resv_regions,
 	.put_resv_regions	= generic_iommu_put_resv_regions,
+	.dev_has_feat		= arm_smmu_dev_has_feature,
+	.dev_feat_enabled	= arm_smmu_dev_feature_enabled,
+	.dev_enable_feat	= arm_smmu_dev_enable_feature,
+	.dev_disable_feat	= arm_smmu_dev_disable_feature,
 	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
 };
 

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

@@ -647,6 +647,8 @@ struct arm_smmu_master {
 	u32				*sids;
 	unsigned int			num_sids;
 	bool				ats_enabled;
+	bool				sva_enabled;
+	struct list_head		bonds;
 	unsigned int			ssid_bits;
 };
 
@@ -688,10 +690,34 @@ bool arm_smmu_free_asid(struct arm_smmu_ctx_desc *cd);
 
 #ifdef CONFIG_ARM_SMMU_V3_SVA
 bool arm_smmu_sva_supported(struct arm_smmu_device *smmu);
+bool arm_smmu_master_sva_supported(struct arm_smmu_master *master);
+bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master);
+int arm_smmu_master_enable_sva(struct arm_smmu_master *master);
+int arm_smmu_master_disable_sva(struct arm_smmu_master *master);
 #else /* CONFIG_ARM_SMMU_V3_SVA */
 static inline bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
 {
 	return false;
 }
+
+static inline bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
+{
+	return false;
+}
+
+static inline bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
+{
+	return false;
+}
+
+static inline int arm_smmu_master_enable_sva(struct arm_smmu_master *master)
+{
+	return -ENODEV;
+}
+
+static inline int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
+{
+	return -ENODEV;
+}
 #endif /* CONFIG_ARM_SMMU_V3_SVA */
 #endif /* _ARM_SMMU_V3_H */