Hi Cédric, Please find my comments inline: On 2025/08/08 03:49 PM, Cédric Le Goater wrote: > Hello Amit, > > On 8/7/25 11:34, Amit Machhiwal wrote: > > Hello, > > > > On 2025/08/04 12:44 PM, Alex Mastro wrote: > > > 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@xxxxxx> > > > > I tested this patch on a POWER9 bare metal system with a VFIO PCI device and > > could see the VFIO device syspath in fdinfo. > > POWER9 running on OPAL FW : I am curious about the software stack. > > I suppose this is the latest upstream kernel ? Yes, I used the latest upstream kernel and applied this patch on top of commit cca7a0aae895. > Are you using an upstream QEMU to test too ? No, I had used the Fedora 42 distro qemu. The version details are as below: [root@localhost ~]# qemu-system-ppc64 --version QEMU emulator version 9.2.4 (qemu-9.2.4-1.fc42) Copyright (c) 2003-2024 Fabrice Bellard and the QEMU Project developers I gave the upstream qemu (HEAD pointing to cd21ee5b27) a try and I see the same behavior with that too. [root@localhost ~]# ./qemu-system-ppc64 --version QEMU emulator version 10.0.92 (v10.1.0-rc2-4-gcd21ee5b27-dirty) Copyright (c) 2003-2025 Fabrice Bellard and the QEMU Project developers [root@localhost ~]# cat /proc/52807/fdinfo/191 pos: 0 flags: 02000002 mnt_id: 17 ino: 1125 vfio-device-syspath: /sys/devices/pci0031:00/0031:00:00.0/0031:01:00.0 > > and which device ? I'm using a Broadcom NetXtreme network card (4-port) and passing through its fn0. [root@guest ~]# lspci [...] 0001:00:01.0 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01) Please let me know if I may help you with any additional information. Thanks, Amit > > Thanks, > > C. > > > > > > > > Without this patch: > > ------------------- > > > > [root@localhost ~]# cat /proc/7059/fdinfo/188 > > pos: 0 > > flags: 02000002 > > mnt_id: 17 > > ino: 1113 > > > > With this patch: > > ---------------- > > [root@localhost ~]# cat /proc/7722/fdinfo/188 > > pos: 0 > > flags: 02000002 > > mnt_id: 17 > > ino: 2145 > > vfio-device-syspath: /sys/devices/pci0031:00/0031:00:00.0/0031:01:00.0 > > > > ..., and the code changes LGTM. Hence, > > > > Reviewed-by: Amit Machhiwal <amachhiw@xxxxxxxxxxxxx> > > Tested-by: Amit Machhiwal <amachhiw@xxxxxxxxxxxxx> > > > > Thanks, > > Amit > > > > > --- > > > Changes in v4: > > > - Remove changes to vfio.h > > > - Link to v3: https://lore.kernel.org/r/20250801-show-fdinfo-v3-1-165dfcab89b9@xxxxxx > > > Changes in v3: > > > - Remove changes to vfio_pci.c > > > - Add section to Documentation/filesystems/proc.rst > > > - Link to v2: https://lore.kernel.org/all/20250724-show-fdinfo-v2-1-2952115edc10@xxxxxx > > > Changes in v2: > > > - Instead of PCI bdf, print the fully-qualified syspath (prefixed by > > > /sys) to fdinfo. > > > - Rename the field to "vfio-device-syspath". The term "syspath" was > > > chosen for consistency e.g. libudev's usage of the term. > > > - Link to v1: https://lore.kernel.org/r/20250623-vfio-fdinfo-v1-1-c9cec65a2922@xxxxxx > > > --- > > > Documentation/filesystems/proc.rst | 14 ++++++++++++++ > > > drivers/vfio/vfio_main.c | 20 ++++++++++++++++++++ > > > 2 files changed, 34 insertions(+) > > > > > > diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst > > > index 2a17865dfe39..fc5ed3117834 100644 > > > --- a/Documentation/filesystems/proc.rst > > > +++ b/Documentation/filesystems/proc.rst > > > @@ -2162,6 +2162,20 @@ 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 > > > diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c > > > index 1fd261efc582..37a39cee10ed 100644 > > > --- a/drivers/vfio/vfio_main.c > > > +++ b/drivers/vfio/vfio_main.c > > > @@ -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> > > > @@ -1354,6 +1355,22 @@ 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, > > > @@ -1363,6 +1380,9 @@ 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) > > > > > > --- > > > base-commit: 4518e5a60c7fbf0cdff393c2681db39d77b4f87e > > > change-id: 20250801-show-fdinfo-ef109ca738cf > > > > > > Best regards, > > > -- > > > Alex Mastro <amastro@xxxxxx> > > > > > >
