[PATCH v3 5/9] vfio: Create interface for vfio bus drivers to register

Alex Williamson
2017-06-20T15:48:18Z

Generally we don't know about vfio bus drivers until a device is
added to the vfio-core with vfio_add_group_dev(), this optional
registration with vfio_register_bus_driver() allows vfio-core to
track known drivers. Our current use for this information is to
know whether a driver is vfio compatible during a bind operation.
For devices on buses with driver_override support, we can use this
linkage to block non-vfio drivers from binding to devices where
the iommu group state would trigger a BUG to avoid host/user
integrity issues.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
---
drivers/vfio/vfio.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/vfio.h | 3 +++
2 files changed, 58 insertions(+)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 7597a377eb4e..f40d1508d368 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -43,6 +43,8 @@
struct class *class;
struct list_head iommu_drivers_list;
struct mutex iommu_drivers_lock;
+ struct list_head bus_drivers_list;
+ struct mutex bus_drivers_lock;
struct list_head group_list;
struct idr group_idr;
struct mutex group_lock;
@@ -51,6 +53,11 @@
wait_queue_head_t release_q;
} vfio;

+struct vfio_bus_driver {
+ struct device_driver *drv;
+ struct list_head vfio_next;
+};
+
struct vfio_iommu_driver {
const struct vfio_iommu_driver_ops *ops;
struct list_head vfio_next;
@@ -2243,6 +2250,52 @@ int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type,
}
EXPORT_SYMBOL(vfio_unregister_notifier);

+int vfio_register_bus_driver(struct device_driver *drv)
+{
+ struct vfio_bus_driver *driver, *tmp;
+
+ driver = kzalloc(sizeof(*driver), GFP_KERNEL);
+ if (!driver)
+ return -ENOMEM;
+
+ driver->drv = drv;
+
+ mutex_lock(&vfio.bus_drivers_lock);
+
+ /* Check for duplicates */
+ list_for_each_entry(tmp, &vfio.bus_drivers_list, vfio_next) {
+ if (tmp->drv == drv) {
+ mutex_unlock(&vfio.bus_drivers_lock);
+ kfree(driver);
+ return -EINVAL;
+ }
+ }
+
+ list_add(&driver->vfio_next, &vfio.bus_drivers_list);
+
+ mutex_unlock(&vfio.bus_drivers_lock);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_register_bus_driver);
+
+void vfio_unregister_bus_driver(struct device_driver *drv)
+{
+ struct vfio_bus_driver *driver;
+
+ mutex_lock(&vfio.bus_drivers_lock);
+ list_for_each_entry(driver, &vfio.bus_drivers_list, vfio_next) {
+ if (driver->drv == drv) {
+ list_del(&driver->vfio_next);
+ mutex_unlock(&vfio.bus_drivers_lock);
+ kfree(driver);
+ return;
+ }
+ }
+ mutex_unlock(&vfio.bus_drivers_lock);
+}
+EXPORT_SYMBOL_GPL(vfio_unregister_bus_driver);
+
/**
* Module/class support
*/
@@ -2266,8 +2319,10 @@ static int __init vfio_init(void)
idr_init(&vfio.group_idr);
mutex_init(&vfio.group_lock);
mutex_init(&vfio.iommu_drivers_lock);
+ mutex_init(&vfio.bus_drivers_lock);
INIT_LIST_HEAD(&vfio.group_list);
INIT_LIST_HEAD(&vfio.iommu_drivers_list);
+ INIT_LIST_HEAD(&vfio.bus_drivers_list);
init_waitqueue_head(&vfio.release_q);

ret = misc_register(&vfio_dev);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 9b34d0af5d27..dab0f8105e4a 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -92,6 +92,9 @@ struct vfio_iommu_driver_ops {
extern void vfio_unregister_iommu_driver(
const struct vfio_iommu_driver_ops *ops);

+extern int vfio_register_bus_driver(struct device_driver *drv);
+extern void vfio_unregister_bus_driver(struct device_driver *drv);
+
/*
* External user API
*/