[PATCH v3 1/1] vfio/type1: Add vfio_group_domain()

Lu Baolu
2020-12-01T01:32:59Z

Add the API for getting the domain from a vfio group. This could be used
by the physical device drivers which rely on the vfio/mdev framework for
mediated device user level access. The typical use case like below:

unsigned int pasid;
struct vfio_group *vfio_group;
struct iommu_domain *iommu_domain;
struct device *dev = mdev_dev(mdev);
struct device *iommu_device = mdev_get_iommu_device(dev);

if (!iommu_device ||
!iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX))
return -EINVAL;

vfio_group = vfio_group_get_external_user_from_dev(dev);
if (IS_ERR_OR_NULL(vfio_group))
return -EFAULT;

iommu_domain = vfio_group_domain(vfio_group);
if (IS_ERR_OR_NULL(iommu_domain)) {
vfio_group_put_external_user(vfio_group);
return -EFAULT;
}

pasid = iommu_aux_get_pasid(iommu_domain, iommu_device);
if (pasid < 0) {
vfio_group_put_external_user(vfio_group);
return -EFAULT;
}

/* Program device context with pasid value. */
...

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/vfio/vfio.c | 18 ++++++++++++++++++
drivers/vfio/vfio_iommu_type1.c | 23 +++++++++++++++++++++++
include/linux/vfio.h | 3 +++
3 files changed, 44 insertions(+)

Change log:
- v2: https://lore.kernel.org/linux-iommu/20201126012726.1185171-1-baolu.lu@linux.intel.com/
- Changed according to comments @ https://lore.kernel.org/linux-iommu/20201130135725.70fdf17f@w520.home/
- Fix a typo https://lore.kernel.org/linux-iommu/DM5PR11MB143560E51C84BAF83AE54AC0C3F90@DM5PR11MB1435.namprd11.prod.outlook.com/

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 2151bc7f87ab..588e8026d94b 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -2331,6 +2331,24 @@ int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type,
}
EXPORT_SYMBOL(vfio_unregister_notifier);

+struct iommu_domain *vfio_group_domain(struct vfio_group *group)
+{
+ struct vfio_container *container;
+ struct vfio_iommu_driver *driver;
+
+ if (!group)
+ return ERR_PTR(-EINVAL);
+
+ container = group->container;
+ driver = container->iommu_driver;
+ if (likely(driver && driver->ops->group_domain))
+ return driver->ops->group_domain(container->iommu_data,
+ group->iommu_group);
+ else
+ return ERR_PTR(-ENOTTY);
+}
+EXPORT_SYMBOL_GPL(vfio_group_domain);
+
/**
* Module/class support
*/
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 67e827638995..d7b5acb3056a 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2980,6 +2980,28 @@ static int vfio_iommu_type1_dma_rw(void *iommu_data, dma_addr_t user_iova,
return ret;
}

+static struct iommu_domain *
+vfio_iommu_type1_group_domain(void *iommu_data, struct iommu_group *iommu_group)
+{
+ struct iommu_domain *domain = ERR_PTR(-ENODEV);
+ struct vfio_iommu *iommu = iommu_data;
+ struct vfio_domain *d;
+
+ if (!iommu || !iommu_group)
+ return ERR_PTR(-EINVAL);
+
+ mutex_lock(&iommu->lock);
+ list_for_each_entry(d, &iommu->domain_list, next) {
+ if (find_iommu_group(d, iommu_group)) {
+ domain = d->domain;
+ break;
+ }
+ }
+ mutex_unlock(&iommu->lock);
+
+ return domain;
+}
+
static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
.name = "vfio-iommu-type1",
.owner = THIS_MODULE,
@@ -2993,6 +3015,7 @@ static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
.register_notifier = vfio_iommu_type1_register_notifier,
.unregister_notifier = vfio_iommu_type1_unregister_notifier,
.dma_rw = vfio_iommu_type1_dma_rw,
+ .group_domain = vfio_iommu_type1_group_domain,
};

static int __init vfio_iommu_type1_init(void)
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 38d3c6a8dc7e..6cd0de2764cb 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -90,6 +90,7 @@ struct vfio_iommu_driver_ops {
struct notifier_block *nb);
int (*dma_rw)(void *iommu_data, dma_addr_t user_iova,
void *data, size_t count, bool write);
+ struct iommu_domain *(*group_domain)(void *iommu_data, struct iommu_group *group);
};

extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
@@ -126,6 +127,8 @@ extern int vfio_group_unpin_pages(struct vfio_group *group,
extern int vfio_dma_rw(struct vfio_group *group, dma_addr_t user_iova,
void *data, size_t len, bool write);

+extern struct iommu_domain *vfio_group_domain(struct vfio_group *group);
+
/* each type has independent events */
enum vfio_notify_type {
VFIO_IOMMU_NOTIFY = 0,
--
2.25.1