[PATCH v2 09/10] vfio/pci: Accept device fd in VFIO_DEVICE_PCI_HOT_RESET ioctl

Yi Liu
2023-03-27T09:35:56Z

Now user can also provide an array of device fds as a 3rd method to verify
the reset ownership. It's not useful at this point when the device fds are
acquired via group fds. But it's necessary when moving to device cdev which
allows the user to directly acquire device fds by skipping group. In that
case this method can be used as a last resort when the preferred iommufd
verification doesn't work, e.g. in noiommu usages.

Clarify it in uAPI.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/vfio/pci/vfio_pci_core.c | 9 +++++----
include/uapi/linux/vfio.h | 3 ++-
2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index da6325008872..19f5b075d70a 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1289,7 +1289,7 @@ vfio_pci_ioctl_pci_hot_reset_files(struct vfio_pci_core_device *vdev,
return -ENOMEM;
}

- if (copy_from_user(fds, arg->group_fds,
+ if (copy_from_user(fds, arg->fds,
hdr->count * sizeof(*fds))) {
kfree(fds);
kfree(files);
@@ -1297,8 +1297,8 @@ vfio_pci_ioctl_pci_hot_reset_files(struct vfio_pci_core_device *vdev,
}

/*
- * Get the group file for each fd to ensure the group held across
- * the reset
+ * Get the file for each fd to ensure the group/device file
+ * is held across the reset
*/
for (file_idx = 0; file_idx < hdr->count; file_idx++) {
struct file *file = fget(fds[file_idx]);
@@ -2469,7 +2469,8 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set,
* cannot race being opened by another user simultaneously.
*
* Otherwise all opened devices in the dev_set must be
- * contained by the set of groups provided by the user.
+ * contained by the set of groups/devices provided by
+ * the user.
*
* If user provides a zero-length array, then all the
* opened devices must be bound to a same iommufd_ctx.
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 17aa5d09db41..25432ef213ee 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -681,6 +681,7 @@ struct vfio_pci_hot_reset_info {
*
* The ownership can be proved by:
* - An array of group fds
+ * - An array of device fds
* - A zero-length array
*
* In the last case all affected devices which are opened by this user
@@ -694,7 +695,7 @@ struct vfio_pci_hot_reset {
__u32 argsz;
__u32 flags;
__u32 count;
- __s32 group_fds[];
+ __s32 fds[];
};

#define VFIO_DEVICE_PCI_HOT_RESET _IO(VFIO_TYPE, VFIO_BASE + 13)
--
2.34.1