[PATCH RFC v2 04/11] iommu: Add attach/detach_dev_pasid domain ops

[Lu Baolu <baolu.lu@linux.intel.com>]

Attaching an IOMMU domain to a PASID of a device is a generic operation
for modern IOMMU drivers which support PASID-granular DMA address
translation. Currently visible usage scenarios include (but not limited):

 - SVA (Shared Virtual Address)
 - kernel DMA with PASID
 - hardware-assist mediated device

This adds a pair of common domain ops for this purpose and adds some
common helpers to attach/detach a domain to/from a {device, PASID} and
get/put the domain attached to {device, PASID}.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 include/linux/iommu.h | 36 ++++++++++++++++++
 drivers/iommu/iommu.c | 88 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 124 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 29c4c2edd706..a46285488a57 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -269,6 +269,8 @@ struct iommu_ops {
  * struct iommu_domain_ops - domain specific operations
  * @attach_dev: attach an iommu domain to a device
  * @detach_dev: detach an iommu domain from a device
+ * @attach_dev_pasid: attach an iommu domain to a pasid of device
+ * @detach_dev_pasid: detach an iommu domain from a pasid of device
  * @map: map a physically contiguous memory region to an iommu domain
  * @map_pages: map a physically contiguous set of pages of the same size to
  *             an iommu domain.
@@ -286,6 +288,10 @@ struct iommu_ops {
 struct iommu_domain_ops {
 	int (*attach_dev)(struct iommu_domain *domain, struct device *dev);
 	void (*detach_dev)(struct iommu_domain *domain, struct device *dev);
+	int (*attach_dev_pasid)(struct iommu_domain *domain,
+				struct device *dev, ioasid_t id);
+	void (*detach_dev_pasid)(struct iommu_domain *domain,
+				 struct device *dev, ioasid_t id);
 
 	int (*map)(struct iommu_domain *domain, unsigned long iova,
 		   phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
@@ -679,6 +685,14 @@ int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner);
 void iommu_group_release_dma_owner(struct iommu_group *group);
 bool iommu_group_dma_owner_claimed(struct iommu_group *group);
 
+int iommu_attach_device_pasid(struct iommu_domain *domain,
+			      struct device *dev, ioasid_t pasid);
+void iommu_detach_device_pasid(struct iommu_domain *domain,
+			       struct device *dev, ioasid_t pasid);
+struct iommu_domain *
+iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid);
+void iommu_put_domain_for_dev_pasid(struct iommu_domain *domain);
+
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
@@ -1047,6 +1061,28 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
 {
 	return false;
 }
+
+static inline int iommu_attach_device_pasid(struct iommu_domain *domain,
+					    struct device *dev, ioasid_t pasid)
+{
+	return -ENODEV;
+}
+
+static inline void iommu_detach_device_pasid(struct iommu_domain *domain,
+					     struct device *dev, ioasid_t pasid)
+{
+}
+
+static inline struct iommu_domain *
+iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid)
+{
+	return NULL;
+}
+
+static inline void
+iommu_put_domain_for_dev_pasid(struct iommu_domain *domain)
+{
+}
 #endif /* CONFIG_IOMMU_API */
 
 /**
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 9fb8a5b4491e..8163ad7f6902 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -27,6 +27,8 @@
 #include <linux/cc_platform.h>
 #include <trace/events/iommu.h>
 
+#include "iommu-sva-lib.h"
+
 static struct kset *iommu_group_kset;
 static DEFINE_IDA(iommu_group_ida);
 
@@ -38,6 +40,7 @@ struct iommu_group {
 	struct kobject kobj;
 	struct kobject *devices_kobj;
 	struct list_head devices;
+	struct xarray pasid_array;
 	struct mutex mutex;
 	void *iommu_data;
 	void (*iommu_data_release)(void *iommu_data);
@@ -631,6 +634,7 @@ struct iommu_group *iommu_group_alloc(void)
 	mutex_init(&group->mutex);
 	INIT_LIST_HEAD(&group->devices);
 	INIT_LIST_HEAD(&group->entry);
+	xa_init(&group->pasid_array);
 
 	ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL);
 	if (ret < 0) {
@@ -3173,3 +3177,87 @@ bool iommu_group_dma_owner_claimed(struct iommu_group *group)
 	return user;
 }
 EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);
+
+int iommu_attach_device_pasid(struct iommu_domain *domain,
+			      struct device *dev, ioasid_t pasid)
+{
+	struct iommu_group *group;
+	int ret = -EINVAL;
+	void *curr;
+
+	if (!domain->ops->attach_dev_pasid)
+		return -EINVAL;
+
+	group = iommu_group_get(dev);
+	if (!group)
+		return -ENODEV;
+
+	mutex_lock(&group->mutex);
+	/*
+	 * To keep things simple, we currently don't support IOMMU groups
+	 * with more than one device. Existing SVA-capable systems are not
+	 * affected by the problems that required IOMMU groups (lack of ACS
+	 * isolation, device ID aliasing and other hardware issues).
+	 */
+	if (!iommu_group_singleton_lockdown(group))
+		goto out_unlock;
+
+	xa_lock(&group->pasid_array);
+	curr = __xa_cmpxchg(&group->pasid_array, pasid, NULL,
+			    domain, GFP_KERNEL);
+	xa_unlock(&group->pasid_array);
+	if (curr)
+		goto out_unlock;
+
+	ret = domain->ops->attach_dev_pasid(domain, dev, pasid);
+	if (ret)
+		xa_erase(&group->pasid_array, pasid);
+
+out_unlock:
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
+
+	return ret;
+}
+
+void iommu_detach_device_pasid(struct iommu_domain *domain,
+			       struct device *dev, ioasid_t pasid)
+{
+	struct iommu_group *group;
+
+	group = iommu_group_get(dev);
+	if (WARN_ON(!group))
+		return;
+
+	mutex_lock(&group->mutex);
+	domain->ops->detach_dev_pasid(domain, dev, pasid);
+	xa_erase(&group->pasid_array, pasid);
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
+}
+
+struct iommu_domain *
+iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid)
+{
+	struct iommu_domain *domain;
+	struct iommu_group *group;
+
+	group = iommu_group_get(dev);
+	if (!group)
+		return NULL;
+
+	mutex_lock(&group->mutex);
+	domain = xa_load(&group->pasid_array, pasid);
+	if (domain && domain->type == IOMMU_DOMAIN_SVA)
+		iommu_sva_domain_get_user(domain);
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
+
+	return domain;
+}
+
+void iommu_put_domain_for_dev_pasid(struct iommu_domain *domain)
+{
+	if (domain->type == IOMMU_DOMAIN_SVA)
+		iommu_sva_domain_put_user(domain);
+}
-- 
2.25.1