From: Yan Zhao yan.y.zhao@intel.com
mainline inclusion from mainline-v5.6-rc7 commit c0560f51cf77472f4ed113539b0a02ca6cda7961 category: Common features bugzilla: 46841 CVE: NA
-------------------------------------------------
external user calls vfio_group_get_external_user_from_dev() with a device pointer to get the VFIO group associated with this device. The VFIO group is checked to be vialbe and have IOMMU set. Then container user counter is increased and VFIO group reference is hold to prevent the VFIO group from disposal before external user exits.
when the external user finishes using of the VFIO group, it calls vfio_group_put_external_user() to dereference the VFIO group and the container user counter.
Suggested-by: Alex Williamson alex.williamson@redhat.com Signed-off-by: Yan Zhao yan.y.zhao@intel.com Signed-off-by: Alex Williamson alex.williamson@redhat.com Signed-off-by: Xiaoyang Xu xuxiaoyang2@huawei.com Reviewed-by: Xiangyou Xie xiexiangyou@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/vfio/vfio.c | 38 ++++++++++++++++++++++++++++++++++++++ include/linux/vfio.h | 2 ++ 2 files changed, 40 insertions(+)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 7a386fb30bf1..34a293318a39 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -1759,6 +1759,44 @@ struct vfio_group *vfio_group_get_external_user(struct file *filep) } EXPORT_SYMBOL_GPL(vfio_group_get_external_user);
+/** + * External user API, exported by symbols to be linked dynamically. + * The external user passes in a device pointer + * to verify that: + * - A VFIO group is assiciated with the device; + * - IOMMU is set for the group. + * If both checks passed, vfio_group_get_external_user_from_dev() + * increments the container user counter to prevent the VFIO group + * from disposal before external user exits and returns the pointer + * to the VFIO group. + * + * When the external user finishes using the VFIO group, it calls + * vfio_group_put_external_user() to release the VFIO group and + * decrement the container user counter. + * + * @dev [in] : device + * Return error PTR or pointer to VFIO group. + */ + +struct vfio_group *vfio_group_get_external_user_from_dev(struct device *dev) +{ + struct vfio_group *group; + int ret; + + group = vfio_group_get_from_dev(dev); + if (!group) + return ERR_PTR(-ENODEV); + + ret = vfio_group_add_container_user(group); + if (ret) { + vfio_group_put(group); + return ERR_PTR(ret); + } + + return group; +} +EXPORT_SYMBOL_GPL(vfio_group_get_external_user_from_dev); + void vfio_group_put_external_user(struct vfio_group *group) { vfio_group_try_dissolve_container(group); diff --git a/include/linux/vfio.h b/include/linux/vfio.h index 66741ab087c1..a1e8943b7be3 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -97,6 +97,8 @@ extern void vfio_unregister_iommu_driver( */ extern struct vfio_group *vfio_group_get_external_user(struct file *filep); extern void vfio_group_put_external_user(struct vfio_group *group); +extern struct vfio_group *vfio_group_get_external_user_from_dev(struct device + *dev); extern bool vfio_external_group_match_file(struct vfio_group *group, struct file *filep); extern int vfio_external_user_iommu_id(struct vfio_group *group);