[PATCH RFC 03/11] 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
 - kernel DMA with PASID
 - hardware-assist mediated device

This adds a pair of common domain ops for this purpose and implements a
couple of wrapper helpers for in-kernel usage.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 include/linux/iommu.h | 22 ++++++++++++++++++++++
 drivers/iommu/iommu.c | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 3e179b853380..e51845b9a146 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -268,6 +268,8 @@ 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.
@@ -285,6 +287,10 @@ 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);
@@ -678,6 +684,11 @@ 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);
+
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
@@ -1046,6 +1057,17 @@ 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)
+{
+}
 #endif /* CONFIG_IOMMU_API */
 
 /**
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 0c42ece25854..78c71ee15f36 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3167,3 +3167,44 @@ 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;
+
+	if (!domain->ops->attach_dev_pasid)
+		return -EINVAL;
+
+	group = iommu_group_get(dev);
+	if (!group)
+		return -ENODEV;
+
+	mutex_lock(&group->mutex);
+	if (iommu_group_device_count(group) != 1)
+		goto out_unlock;
+
+	ret = domain->ops->attach_dev_pasid(domain, dev, 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);
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
+}
-- 
2.25.1