Enforce that files for incoming (preserved by previous kernel) VFIO devices are retrieved via LIVEUPDATE_SESSION_RETRIEVE_FD rather than by opening the corresponding VFIO character device or via VFIO_GROUP_GET_DEVICE_FD.
Both of these methods would result in VFIO initializing the device without access to the preserved state of the device passed by the previous kernel. Signed-off-by: David Matlack <[email protected]> --- drivers/vfio/device_cdev.c | 4 ++++ drivers/vfio/group.c | 9 +++++++++ include/linux/vfio.h | 11 +++++++++++ 3 files changed, 24 insertions(+) diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c index 0a6e972f322b..f1e54dcc04e7 100644 --- a/drivers/vfio/device_cdev.c +++ b/drivers/vfio/device_cdev.c @@ -57,6 +57,10 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep) struct vfio_device *device = container_of(inode->i_cdev, struct vfio_device, cdev); + /* Device file must be retrieved via LIVEUPDATE_SESSION_RETRIEVE_FD */ + if (vfio_liveupdate_incoming_is_preserved(device)) + return -EBUSY; + return __vfio_device_fops_cdev_open(device, filep); } diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c index c376a6279de0..93dbbf37ec4c 100644 --- a/drivers/vfio/group.c +++ b/drivers/vfio/group.c @@ -313,6 +313,15 @@ static int vfio_group_ioctl_get_device_fd(struct vfio_group *group, if (IS_ERR(device)) return PTR_ERR(device); + /* + * This device was preserved across a Live Update. Accessing it via + * VFIO_GROUP_GET_DEVICE_FD is not allowed. + */ + if (vfio_liveupdate_incoming_is_preserved(device)) { + ret = -EBUSY; + goto err_put_device; + } + fdno = get_unused_fd_flags(O_CLOEXEC); if (fdno < 0) { ret = fdno; diff --git a/include/linux/vfio.h b/include/linux/vfio.h index 4e400a7219ea..040c2b2ee074 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -16,6 +16,7 @@ #include <linux/cdev.h> #include <uapi/linux/vfio.h> #include <linux/iova_bitmap.h> +#include <linux/pci.h> struct kvm; struct iommufd_ctx; @@ -425,4 +426,14 @@ static inline int __vfio_device_fops_cdev_open(struct vfio_device *device, struct vfio_device *vfio_find_device(const void *data, device_match_t match); +static inline bool vfio_liveupdate_incoming_is_preserved(struct vfio_device *device) +{ + struct device *d = device->dev; + + if (dev_is_pci(d)) + return pci_liveupdate_incoming_is_preserved(to_pci_dev(d)); + + return false; +} + #endif /* VFIO_H */ -- 2.52.0.487.g5c8c507ade-goog
