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vfio/pci: print vfio-device syspath to fdinfo 

Print the PCI device syspath to a vfio device's fdinfo. This enables tools
to query which device is associated with a given vfio device fd.

This results in output like below:

$ cat /proc/"$SOME_PID"/fdinfo/"$VFIO_FD" | grep vfio
vfio-device-syspath: /sys/devices/pci0000:e0/0000:e0:01.1/0000:e1:00.0/0000:e2:05.0/0000:e8:00.0

Signed-off-by: Alex Mastro <amastro@fb.com>
Reviewed-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Tested-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Link: https://lore.kernel.org/r/20250804-show-fdinfo-v4-1-96b14c5691b3@fb.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Mastro 2025-08-04 12:44:31 -07:00 committed by Alex Williamson
parent 1b237f190e
commit 1e736f1489
2 changed files with 34 additions and 0 deletions
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14
Documentation/filesystems/proc.rst
View File

@ -2166,6 +2166,20 @@ DMA Buffer files
where 'size' is the size of the DMA buffer in bytes. 'count' is the file count of
the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter.
VFIO Device files
~~~~~~~~~~~~~~~~
::
pos: 0
flags: 02000002
mnt_id: 17
ino: 5122
vfio-device-syspath: /sys/devices/pci0000:e0/0000:e0:01.1/0000:e1:00.0/0000:e2:05.0/0000:e8:00.0
where 'vfio-device-syspath' is the sysfs path corresponding to the VFIO device
file.
3.9 /proc/<pid>/map_files - Information about memory mapped files
---------------------------------------------------------------------
This directory contains symbolic links which represent memory mapped files

20
drivers/vfio/vfio_main.c
View File

@ -28,6 +28,7 @@
#include <linux/pseudo_fs.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/string.h>
@ -1355,6 +1356,22 @@ static int vfio_device_fops_mmap(struct file *filep, struct vm_area_struct *vma)
return device->ops->mmap(device, vma);
}
#ifdef CONFIG_PROC_FS
static void vfio_device_show_fdinfo(struct seq_file *m, struct file *filep)
{
char *path;
struct vfio_device_file *df = filep->private_data;
struct vfio_device *device = df->device;
path = kobject_get_path(&device->dev->kobj, GFP_KERNEL);
if (!path)
return;
seq_printf(m, "vfio-device-syspath: /sys%s\n", path);
kfree(path);
}
#endif
const struct file_operations vfio_device_fops = {
.owner = THIS_MODULE,
.open = vfio_device_fops_cdev_open,
@ -1364,6 +1381,9 @@ const struct file_operations vfio_device_fops = {
.unlocked_ioctl = vfio_device_fops_unl_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.mmap = vfio_device_fops_mmap,
#ifdef CONFIG_PROC_FS
.show_fdinfo = vfio_device_show_fdinfo,
#endif
};
static struct vfio_device *vfio_device_from_file(struct file *file)