iommu/arm-smmu: add support for multi-master iommu groups

Whilst the driver currently creates one IOMMU group per device, this
will soon change when we start supporting non-transparent PCI bridges
which require all upstream masters to be assigned to the same address
space.

This patch reworks our IOMMU group code so that we can easily support
multi-master groups. The master configuration (streamids and smrs) is
stored as private iommudata on the group, whilst the low-level attach/detach
code is updated to avoid double alloc/free when dealing with multiple
masters sharing the same SMMU configuration. This unifies device
handling, regardless of whether the device sits on the platform or pci
bus.

Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 39 insertions, 26 deletions

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 958ae8194afe..38f8d670afb3 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -431,17 +431,17 @@ static void parse_driver_options(struct arm_smmu_device *smmu)
         } while (arm_smmu_options[++i].opt);
 }
 
-static struct device *dev_get_master_dev(struct device *dev)
+static struct device_node *dev_get_dev_node(struct device *dev)
 {
         if (dev_is_pci(dev)) {
                 struct pci_bus *bus = to_pci_dev(dev)->bus;
 
                 while (!pci_is_root_bus(bus))
                         bus = bus->parent;
-                return bus->bridge->parent;
+                return bus->bridge->parent->of_node;
         }
 
-        return dev;
+        return dev->of_node;
 }
 
 static struct arm_smmu_master *find_smmu_master(struct arm_smmu_device *smmu,
@@ -466,15 +466,17 @@ static struct arm_smmu_master *find_smmu_master(struct arm_smmu_device *smmu,
 }
 
 static struct arm_smmu_master_cfg *
-find_smmu_master_cfg(struct arm_smmu_device *smmu, struct device *dev)
+find_smmu_master_cfg(struct device *dev)
 {
-        struct arm_smmu_master *master;
+        struct arm_smmu_master_cfg *cfg = NULL;
+        struct iommu_group *group = iommu_group_get(dev);
 
-        if (dev_is_pci(dev))
-                return dev->archdata.iommu;
+        if (group) {
+                cfg = iommu_group_get_iommudata(group);
+                iommu_group_put(group);
+        }
 
-        master = find_smmu_master(smmu, dev->of_node);
-        return master ? &master->cfg : NULL;
+        return cfg;
 }
 
 static int insert_smmu_master(struct arm_smmu_device *smmu,
@@ -550,7 +552,7 @@ static struct arm_smmu_device *find_smmu_for_device(struct device *dev)
 {
         struct arm_smmu_device *smmu;
         struct arm_smmu_master *master = NULL;
-        struct device_node *dev_node = dev_get_master_dev(dev)->of_node;
+        struct device_node *dev_node = dev_get_dev_node(dev);
 
         spin_lock(&arm_smmu_devices_lock);
         list_for_each_entry(smmu, &arm_smmu_devices, list) {
@@ -1156,9 +1158,10 @@ static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain,
         struct arm_smmu_device *smmu = smmu_domain->smmu;
         void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
 
+        /* Devices in an IOMMU group may already be configured */
         ret = arm_smmu_master_configure_smrs(smmu, cfg);
         if (ret)
-                return ret;
+                return ret == -EEXIST ? 0 : ret;
 
         for (i = 0; i < cfg->num_streamids; ++i) {
                 u32 idx, s2cr;
@@ -1179,6 +1182,10 @@ static void arm_smmu_domain_remove_master(struct arm_smmu_domain *smmu_domain,
         struct arm_smmu_device *smmu = smmu_domain->smmu;
         void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
 
+        /* An IOMMU group is torn down by the first device to be removed */
+        if ((smmu->features & ARM_SMMU_FEAT_STREAM_MATCH) && !cfg->smrs)
+                return;
+
         /*
          * We *must* clear the S2CR first, because freeing the SMR means
          * that it can be re-allocated immediately.
@@ -1200,7 +1207,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
         struct arm_smmu_device *smmu, *dom_smmu;
         struct arm_smmu_master_cfg *cfg;
 
-        smmu = dev_get_master_dev(dev)->archdata.iommu;
+        smmu = find_smmu_for_device(dev);
         if (!smmu) {
                 dev_err(dev, "cannot attach to SMMU, is it on the same bus?\n");
                 return -ENXIO;
@@ -1228,7 +1235,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
         }
 
         /* Looks ok, so add the device to the domain */
-        cfg = find_smmu_master_cfg(smmu_domain->smmu, dev);
+        cfg = find_smmu_master_cfg(dev);
         if (!cfg)
                 return -ENODEV;
 
@@ -1240,7 +1247,7 @@ static void arm_smmu_detach_dev(struct iommu_domain *domain, struct device *dev)
         struct arm_smmu_domain *smmu_domain = domain->priv;
         struct arm_smmu_master_cfg *cfg;
 
-        cfg = find_smmu_master_cfg(smmu_domain->smmu, dev);
+        cfg = find_smmu_master_cfg(dev);
         if (cfg)
                 arm_smmu_domain_remove_master(smmu_domain, cfg);
 }
@@ -1554,17 +1561,19 @@ static int __arm_smmu_get_pci_sid(struct pci_dev *pdev, u16 alias, void *data)
         return 0; /* Continue walking */
 }
 
+static void __arm_smmu_release_pci_iommudata(void *data)
+{
+        kfree(data);
+}
+
 static int arm_smmu_add_device(struct device *dev)
 {
         struct arm_smmu_device *smmu;
+        struct arm_smmu_master_cfg *cfg;
         struct iommu_group *group;
+        void (*releasefn)(void *) = NULL;
         int ret;
 
-        if (dev->archdata.iommu) {
-                dev_warn(dev, "IOMMU driver already assigned to device\n");
-                return -EINVAL;
-        }
-
         smmu = find_smmu_for_device(dev);
         if (!smmu)
                 return -ENODEV;
@@ -1576,7 +1585,6 @@ static int arm_smmu_add_device(struct device *dev)
         }
 
         if (dev_is_pci(dev)) {
-                struct arm_smmu_master_cfg *cfg;
                 struct pci_dev *pdev = to_pci_dev(dev);
 
                 cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
@@ -1592,11 +1600,20 @@ static int arm_smmu_add_device(struct device *dev)
                  */
                 pci_for_each_dma_alias(pdev, __arm_smmu_get_pci_sid,
                                        &cfg->streamids[0]);
-                dev->archdata.iommu = cfg;
+                releasefn = __arm_smmu_release_pci_iommudata;
         } else {
-                dev->archdata.iommu = smmu;
+                struct arm_smmu_master *master;
+
+                master = find_smmu_master(smmu, dev->of_node);
+                if (!master) {
+                        ret = -ENODEV;
+                        goto out_put_group;
+                }
+
+                cfg = &master->cfg;
         }
 
+        iommu_group_set_iommudata(group, cfg, releasefn);
         ret = iommu_group_add_device(group, dev);
 
 out_put_group:
@@ -1606,10 +1623,6 @@ out_put_group:
 
 static void arm_smmu_remove_device(struct device *dev)
 {
-        if (dev_is_pci(dev))
-                kfree(dev->archdata.iommu);
-
-        dev->archdata.iommu = NULL;
         iommu_group_remove_device(dev);
 }