diff options
| -rw-r--r-- | drivers/vfio/vfio.c | 62 | ||||
| -rw-r--r-- | include/linux/vfio.h | 7 |
2 files changed, 69 insertions, 0 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 842f4507883e..d3cb34224369 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -1353,6 +1353,68 @@ static const struct file_operations vfio_device_fops = { }; /** + * External user API, exported by symbols to be linked dynamically. + * + * The protocol includes: + * 1. do normal VFIO init operation: + * - opening a new container; + * - attaching group(s) to it; + * - setting an IOMMU driver for a container. + * When IOMMU is set for a container, all groups in it are + * considered ready to use by an external user. + * + * 2. User space passes a group fd to an external user. + * The external user calls vfio_group_get_external_user() + * to verify that: + * - the group is initialized; + * - IOMMU is set for it. + * If both checks passed, vfio_group_get_external_user() + * increments the container user counter to prevent + * the VFIO group from disposal before KVM exits. + * + * 3. The external user calls vfio_external_user_iommu_id() + * to know an IOMMU ID. + * + * 4. When the external KVM finishes, it calls + * vfio_group_put_external_user() to release the VFIO group. + * This call decrements the container user counter. + */ +struct vfio_group *vfio_group_get_external_user(struct file *filep) +{ + struct vfio_group *group = filep->private_data; + + if (filep->f_op != &vfio_group_fops) + return ERR_PTR(-EINVAL); + + if (!atomic_inc_not_zero(&group->container_users)) + return ERR_PTR(-EINVAL); + + if (!group->container->iommu_driver || + !vfio_group_viable(group)) { + atomic_dec(&group->container_users); + return ERR_PTR(-EINVAL); + } + + vfio_group_get(group); + + return group; +} +EXPORT_SYMBOL_GPL(vfio_group_get_external_user); + +void vfio_group_put_external_user(struct vfio_group *group) +{ + vfio_group_put(group); + vfio_group_try_dissolve_container(group); +} +EXPORT_SYMBOL_GPL(vfio_group_put_external_user); + +int vfio_external_user_iommu_id(struct vfio_group *group) +{ + return iommu_group_id(group->iommu_group); +} +EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id); + +/** * Module/class support */ static char *vfio_devnode(struct device *dev, umode_t *mode) diff --git a/include/linux/vfio.h b/include/linux/vfio.h index ac8d488e4372..24579a0312a0 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -90,4 +90,11 @@ extern void vfio_unregister_iommu_driver( TYPE tmp; \ offsetof(TYPE, MEMBER) + sizeof(tmp.MEMBER); }) \ +/* + * External user API + */ +extern struct vfio_group *vfio_group_get_external_user(struct file *filep); +extern void vfio_group_put_external_user(struct vfio_group *group); +extern int vfio_external_user_iommu_id(struct vfio_group *group); + #endif /* VFIO_H */ |