On 2020-06-27 04:15, Lu Baolu wrote:
The hardware assistant vfio mediated device is a use case of iommu
aux-domain. The interactions between vfio/mdev and iommu during mdev
creation and passthr are:
- Create a group for mdev with iommu_group_alloc();
- Add the device to the group with
group = iommu_group_alloc();
if (IS_ERR(group))
return PTR_ERR(group);
ret = iommu_group_add_device(group, &mdev->dev);
if (!ret)
dev_info(&mdev->dev, "MDEV: group_id = %d\n",
iommu_group_id(group));
- Allocate an aux-domain
iommu_domain_alloc()
- Attach the aux-domain to the physical device from which the mdev is
created.
iommu_aux_attach_device()
In the whole process, an iommu group was allocated for the mdev and an
iommu domain was attached to the group, but the group->domain leaves
NULL. As the result, iommu_get_domain_for_dev() doesn't work anymore.
This adds iommu_group_get/set_domain() so that group->domain could be
managed whenever a domain is attached or detached through the aux-domain
api's.
Letting external callers poke around directly in the internals of
iommu_group doesn't look right to me.
If a regular device is attached to one or more aux domains for PASID
use, iommu_get_domain_for_dev() is still going to return the primary
domain, so why should it be expected to behave differently for mediated
devices? AFAICS it's perfectly legitimate to have no primary domain if
traffic-without-PASID is invalid.
Robin.
Fixes: 7bd50f0cd2fd5 ("vfio/type1: Add domain at(de)taching group helpers")
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
drivers/iommu/iommu.c | 28 ++++++++++++++++++++++++++++
include/linux/iommu.h | 14 ++++++++++++++
2 files changed, 42 insertions(+)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d43120eb1dc5..e2b665303d70 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -715,6 +715,34 @@ int iommu_group_set_name(struct iommu_group *group, const char *name)
}
EXPORT_SYMBOL_GPL(iommu_group_set_name);
+/**
+ * iommu_group_get_domain - get domain of a group
+ * @group: the group
+ *
+ * This is called to get the domain of a group.
+ */
+struct iommu_domain *iommu_group_get_domain(struct iommu_group *group)
+{
+ return group->domain;
+}
+EXPORT_SYMBOL_GPL(iommu_group_get_domain);
+
+/**
+ * iommu_group_set_domain - set domain for a group
+ * @group: the group
+ * @domain: iommu domain
+ *
+ * This is called to set the domain for a group. In aux-domain case, a domain
+ * might attach or detach to an iommu group through the aux-domain apis, but
+ * the group->domain doesn't get a chance to be updated there.
+ */
+void iommu_group_set_domain(struct iommu_group *group,
+ struct iommu_domain *domain)
+{
+ group->domain = domain;
+}
+EXPORT_SYMBOL_GPL(iommu_group_set_domain);
+
static int iommu_create_device_direct_mappings(struct iommu_group *group,
struct device *dev)
{
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5f0b7859d2eb..ff88d548a870 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -496,6 +496,9 @@ extern void iommu_group_set_iommudata(struct iommu_group *group,
void *iommu_data,
void (*release)(void *iommu_data));
extern int iommu_group_set_name(struct iommu_group *group, const char *name);
+extern struct iommu_domain *iommu_group_get_domain(struct iommu_group *group);
+extern void iommu_group_set_domain(struct iommu_group *group,
+ struct iommu_domain *domain);
extern int iommu_group_add_device(struct iommu_group *group,
struct device *dev);
extern void iommu_group_remove_device(struct device *dev);
@@ -840,6 +843,17 @@ static inline int iommu_group_set_name(struct iommu_group *group,
return -ENODEV;
}
+static inline
+struct iommu_domain *iommu_group_get_domain(struct iommu_group *group)
+{
+ return NULL;
+}
+
+static inline void iommu_group_set_domain(struct iommu_group *group,
+ struct iommu_domain *domain)
+{
+}
+
static inline int iommu_group_add_device(struct iommu_group *group,
struct device *dev)
{
