[pve-devel] [PATCH common v3 2/2] sysfstools: fix regression on binding to vfio-pci

[Dominik Csapak]

when starting a vm with passthrough, we have to bind all normal pci
devices to vfio-pci. This happens by

* unbinding from current driver
* telling vfio-pci the 'vendorid modelid' combo so it knows this device
  class can use the driver (by writing to 'new_id')
* actually binding the device to vfio-pci

if there are multiple devices of the same 'vendorid modelid' class on
the host (and passed through), only the first write to 'new_id' is
successful, all subsequent ones return EEXIST.

This could happen e.g. for setups with multiple GPUs that have the same
audio chip.

To fix this, ignore the EEXIST error for this write to new_id

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
changes from v2:
* fix typo in commit message

 src/PVE/SysFSTools.pm | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/PVE/SysFSTools.pm b/src/PVE/SysFSTools.pm
index 0aeff5f..c0a1b76 100644
--- a/src/PVE/SysFSTools.pm
+++ b/src/PVE/SysFSTools.pm
@@ -4,6 +4,7 @@ use strict;
 use warnings;
 
 use IO::File;
+use POSIX qw(EEXIST);
 
 use PVE::Tools qw(file_read_firstline dir_glob_foreach);
 
@@ -314,7 +315,7 @@ sub pci_dev_bind_to_vfio {
     return 1 if -d $testdir;
 
     my $data = "$dev->{vendor} $dev->{device}";
-    return undef if !file_write("$vfio_basedir/new_id", $data);
+    return undef if !file_write("$vfio_basedir/new_id", $data, [EEXIST]);
 
     my $fn = "$pcisysfs/devices/$name/driver/unbind";
     if (!file_write($fn, $name)) {
-- 
2.39.5