[PATCH v6 16/25] iommu/arm-smmu-v3: Add SVA device feature

Jean-Philippe Brucker
2020-04-30T14:41:02Z

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

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
drivers/iommu/arm-smmu-v3.c | 125 ++++++++++++++++++++++++++++++++++++
1 file changed, 125 insertions(+)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 9b90cc57a609b..c7942d0540599 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -700,6 +700,8 @@ struct arm_smmu_master {
u32 *sids;
unsigned int num_sids;
bool ats_enabled;
+ bool sva_enabled;
+ struct list_head bonds;
unsigned int ssid_bits;
};

@@ -738,6 +740,7 @@ struct arm_smmu_option_prop {

static DEFINE_XARRAY_ALLOC1(asid_xa);
static DEFINE_SPINLOCK(contexts_lock);
+static DEFINE_MUTEX(arm_smmu_sva_lock);

static struct arm_smmu_option_prop arm_smmu_options[] = {
{ ARM_SMMU_OPT_SKIP_PREFETCH, "hisilicon,broken-prefetch-cmd" },
@@ -3003,6 +3006,19 @@ 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.
+ */
+ mutex_lock(&arm_smmu_sva_lock);
+ if (master->sva_enabled) {
+ mutex_unlock(&arm_smmu_sva_lock);
+ dev_err(dev, "cannot attach - SVA enabled\n");
+ return -EBUSY;
+ }
+ mutex_unlock(&arm_smmu_sva_lock);
+
arm_smmu_detach_dev(master);

mutex_lock(&smmu_domain->init_mutex);
@@ -3151,6 +3167,7 @@ static int arm_smmu_add_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 */
@@ -3220,6 +3237,7 @@ static void arm_smmu_remove_device(struct device *dev)

master = dev_iommu_priv_get(dev);
smmu = master->smmu;
+ WARN_ON(master->sva_enabled);
arm_smmu_detach_dev(master);
iommu_group_remove_device(dev);
iommu_device_unlink(&smmu->iommu, dev);
@@ -3339,6 +3357,109 @@ static void arm_smmu_get_resv_regions(struct device *dev,
iommu_dma_get_resv_regions(dev, head);
}

+static bool arm_smmu_iopf_supported(struct arm_smmu_master *master)
+{
+ return false;
+}
+
+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:
+ 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);
+ default:
+ return false;
+ }
+}
+
+static bool arm_smmu_dev_feature_enabled(struct device *dev,
+ enum iommu_dev_features feat)
+{
+ bool enabled = false;
+ struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
+ if (!master)
+ return false;
+
+ switch (feat) {
+ case IOMMU_DEV_FEAT_SVA:
+ mutex_lock(&arm_smmu_sva_lock);
+ enabled = master->sva_enabled;
+ mutex_unlock(&arm_smmu_sva_lock);
+ return enabled;
+ default:
+ return false;
+ }
+}
+
+static int arm_smmu_dev_enable_sva(struct device *dev)
+{
+ struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
+ mutex_lock(&arm_smmu_sva_lock);
+ master->sva_enabled = true;
+ mutex_unlock(&arm_smmu_sva_lock);
+
+ return 0;
+}
+
+static int arm_smmu_dev_disable_sva(struct device *dev)
+{
+ struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
+ mutex_lock(&arm_smmu_sva_lock);
+ if (!list_empty(&master->bonds)) {
+ dev_err(dev, "cannot disable SVA, device is bound\n");
+ mutex_unlock(&arm_smmu_sva_lock);
+ return -EBUSY;
+ }
+ master->sva_enabled = false;
+ mutex_unlock(&arm_smmu_sva_lock);
+
+ return 0;
+}
+
+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_dev_enable_sva(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_dev_disable_sva(dev);
+ default:
+ return -EINVAL;
+ }
+}
+
static struct iommu_ops arm_smmu_ops = {
.capable = arm_smmu_capable,
.domain_alloc = arm_smmu_domain_alloc,
@@ -3357,6 +3478,10 @@ 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 */
};

--
2.26.2