diff options
Diffstat (limited to 'drivers/vfio/vfio.c')
| -rw-r--r-- | drivers/vfio/vfio.c | 101 |
1 files changed, 73 insertions, 28 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index c488da5db7c7..1eab4ace0671 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -494,27 +494,6 @@ static int vfio_group_nb_add_dev(struct vfio_group *group, struct device *dev) return 0; } -static int vfio_group_nb_del_dev(struct vfio_group *group, struct device *dev) -{ - struct vfio_device *device; - - /* - * Expect to fall out here. If a device was in use, it would - * have been bound to a vfio sub-driver, which would have blocked - * in .remove at vfio_del_group_dev. Sanity check that we no - * longer track the device, so it's safe to remove. - */ - device = vfio_group_get_device(group, dev); - if (likely(!device)) - return 0; - - WARN("Device %s removed from live group %d!\n", dev_name(dev), - iommu_group_id(group->iommu_group)); - - vfio_device_put(device); - return 0; -} - static int vfio_group_nb_verify(struct vfio_group *group, struct device *dev) { /* We don't care what happens when the group isn't in use */ @@ -531,13 +510,11 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb, struct device *dev = data; /* - * Need to go through a group_lock lookup to get a reference or - * we risk racing a group being removed. Leave a WARN_ON for - * debuging, but if the group no longer exists, a spurious notify - * is harmless. + * Need to go through a group_lock lookup to get a reference or we + * risk racing a group being removed. Ignore spurious notifies. */ group = vfio_group_try_get(group); - if (WARN_ON(!group)) + if (!group) return NOTIFY_OK; switch (action) { @@ -545,7 +522,13 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb, vfio_group_nb_add_dev(group, dev); break; case IOMMU_GROUP_NOTIFY_DEL_DEVICE: - vfio_group_nb_del_dev(group, dev); + /* + * Nothing to do here. If the device is in use, then the + * vfio sub-driver should block the remove callback until + * it is unused. If the device is unused or attached to a + * stub driver, then it should be released and we don't + * care that it will be going away. + */ break; case IOMMU_GROUP_NOTIFY_BIND_DRIVER: pr_debug("%s: Device %s, group %d binding to driver\n", @@ -1126,7 +1109,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf) * We can't use anon_inode_getfd() because we need to modify * the f_mode flags directly to allow more than just ioctls */ - ret = get_unused_fd(); + ret = get_unused_fd_flags(O_CLOEXEC); if (ret < 0) { device->ops->release(device->device_data); break; @@ -1370,6 +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) |