Am 04.10.22 um 18:28 schrieb Jason Gunthorpe:
On Tue, Oct 04, 2022 at 05:44:53PM +0200, Christian Borntraeger wrote:
Does some userspace have the group FD open when it stucks like this,
eg what does fuser say?
/proc/<virtnodedevd>/fd
51480 0 dr-x------. 2 root root 0 4. Okt 17:16 .
43593 0 dr-xr-xr-x. 9 root root 0 4. Okt 17:16 ..
65252 0 lr-x------. 1 root root 64 4. Okt 17:42 0 -> /dev/null
65253 0 lrwx------. 1 root root 64 4. Okt 17:42 1 -> 'socket:[51479]'
65261 0 lrwx------. 1 root root 64 4. Okt 17:42 10 -> 'anon_inode:[eventfd]'
65262 0 lrwx------. 1 root root 64 4. Okt 17:42 11 -> 'socket:[51485]'
65263 0 lrwx------. 1 root root 64 4. Okt 17:42 12 -> 'socket:[51487]'
65264 0 lrwx------. 1 root root 64 4. Okt 17:42 13 -> 'socket:[51486]'
65265 0 lrwx------. 1 root root 64 4. Okt 17:42 14 -> 'anon_inode:[eventfd]'
65266 0 lrwx------. 1 root root 64 4. Okt 17:42 15 -> 'socket:[60421]'
65267 0 lrwx------. 1 root root 64 4. Okt 17:42 16 -> 'anon_inode:[eventfd]'
65268 0 lrwx------. 1 root root 64 4. Okt 17:42 17 -> 'socket:[28008]'
65269 0 l-wx------. 1 root root 64 4. Okt 17:42 18 -> /run/libvirt/nodedev/driver.pid
65270 0 lrwx------. 1 root root 64 4. Okt 17:42 19 -> 'socket:[28818]'
65254 0 lrwx------. 1 root root 64 4. Okt 17:42 2 -> 'socket:[51479]'
65271 0 lr-x------. 1 root root 64 4. Okt 17:42 20 -> '/dev/vfio/3 (deleted)'
Seems like a userspace bug to keep the group FD open after the /dev/
file has been deleted :|
What do you think about this?
commit a54a852b1484b1605917a8f4d80691db333b25ed
Author: Jason Gunthorpe <jgg@xxxxxxxx>
Date: Tue Oct 4 13:14:37 2022 -0300
vfio: Make the group FD disassociate from the iommu_group
Allow the vfio_group struct to exist with a NULL iommu_group pointer. When
the pointer is NULL the vfio_group users promise not to touch the
iommu_group. This allows a driver to be hot unplugged while userspace is
keeping the group FD open.
SPAPR mode is excluded from this behavior because of how it wrongly hacks
part of its iommu interface through KVM. Due to this we loose control over
what it is doing and cannot revoke the iommu_group usage in the IOMMU
layer via vfio_group_detach_container().
Thus, for SPAPR the group FDs must still be closed before a device can be
hot unplugged.
This fixes a userspace regression where we learned that virtnodedevd
leaves a group FD open even though the /dev/ node for it has been deleted
and all the drivers for it unplugged.
Fixes: ca5f21b25749 ("vfio: Follow a strict lifetime for struct iommu_group")
Reported-by: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Almost :-)
drivers/vfio/vfio_main.c: In function 'vfio_file_is_group':
drivers/vfio/vfio_main.c:1606:47: error: expected ')' before ';' token
1606 | return (file->f_op == &vfio_group_fops;
| ~ ^
| )
drivers/vfio/vfio_main.c:1606:48: error: expected ';' before '}' token
1606 | return (file->f_op == &vfio_group_fops;
| ^
| ;
1607 | }
| ~
With that fixed I get:
ERROR: modpost: "vfio_file_is_group" [drivers/vfio/pci/vfio-pci-core.ko] undefined!
With that worked around (m -> y)
Tested-by: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
At least the vfio-ap part
