[PATCH v3 3/4] iommu: Add iommu_aux_get_domain_for_dev()

Lu Baolu
2020-07-14T06:02:04Z

The device driver needs an API to get its aux-domain. A typical usage
scenario is:

unsigned long pasid;
struct iommu_domain *domain;
struct device *dev = mdev_dev(mdev);
struct device *iommu_device = vfio_mdev_get_iommu_device(dev);

domain = iommu_aux_get_domain_for_dev(dev);
if (!domain)
return -ENODEV;

pasid = iommu_aux_get_pasid(domain, iommu_device);
if (pasid <= 0)
return -EINVAL;

/* Program the device context */
....

This adds an API for such use case.

Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/iommu.c | 18 ++++++++++++++++++
include/linux/iommu.h | 7 +++++++
2 files changed, 25 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index cad5a19ebf22..434bf42b6b9b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2817,6 +2817,24 @@ void iommu_aux_detach_group(struct iommu_domain *domain,
}
EXPORT_SYMBOL_GPL(iommu_aux_detach_group);

+struct iommu_domain *iommu_aux_get_domain_for_dev(struct device *dev)
+{
+ struct iommu_domain *domain = NULL;
+ struct iommu_group *group;
+
+ group = iommu_group_get(dev);
+ if (!group)
+ return NULL;
+
+ if (group->aux_domain_attached)
+ domain = group->domain;
+
+ iommu_group_put(group);
+
+ return domain;
+}
+EXPORT_SYMBOL_GPL(iommu_aux_get_domain_for_dev);
+
/**
* iommu_sva_bind_device() - Bind a process address space to a device
* @dev: the device
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 9506551139ab..cda6cef7579e 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -639,6 +639,7 @@ int iommu_aux_attach_group(struct iommu_domain *domain,
struct iommu_group *group, struct device *dev);
void iommu_aux_detach_group(struct iommu_domain *domain,
struct iommu_group *group, struct device *dev);
+struct iommu_domain *iommu_aux_get_domain_for_dev(struct device *dev);

struct iommu_sva *iommu_sva_bind_device(struct device *dev,
struct mm_struct *mm,
@@ -1040,6 +1041,12 @@ iommu_aux_detach_group(struct iommu_domain *domain,
{
}

+static inline struct iommu_domain *
+iommu_aux_get_domain_for_dev(struct device *dev)
+{
+ return NULL;
+}
+
static inline struct iommu_sva *
iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
{
--
2.17.1