qemu: fix improper initialization of cgroupControllers bitmap

virQEMUDriverConfigNew() always initializes the bitmap in its
cgroupControllers member to -1 (i.e. all 1's).

Prior to commit a9331394, if qemu.conf had a line with
"cgroup_controllers", cgroupControllers would get reset to 0 before
going through a loop setting a bit for each named cgroup controller.
commit a9331394 left out the "reset to 0" part, so cgroupControllers
would always be -1; if you didn't want a controller included, there
was no longer a way to make that happen.

This was discovered by users who were using qemu commandline
passthrough to use the "input-linux" method of directing
keyboard/mouse input to a virtual machine:

 https://www.redhat.com/archives/vfio-users/2016-April/msg00105.html

Here's the first report I found of the problem encountered after
upgrading libvirt beyond v2.0.0:

 https://www.redhat.com/archives/vfio-users/2016-August/msg00053.html

Thanks to sL1pKn07 SpinFlo <sl1pkn07@gmail.com> for bringing the
problem up in IRC, and then taking the time to do a git bisect and
find the patch that started the problem.
This commit is contained in:
Laine Stump 2016-09-12 13:21:10 -04:00
parent 94e2be8424
commit 0276015325

View File

@ -613,7 +613,9 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg,
&controllers) < 0)
goto cleanup;
for (i = 0; controllers != NULL && controllers[i] != NULL; i++) {
if (controllers) {
cfg-> cgroupControllers = 0;
for (i = 0; controllers[i] != NULL; i++) {
int ctl;
if ((ctl = virCgroupControllerTypeFromString(controllers[i])) < 0) {
virReportError(VIR_ERR_CONF_SYNTAX,
@ -623,6 +625,7 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg,
}
cfg->cgroupControllers |= (1 << ctl);
}
}
if (virConfGetValueStringList(conf, "cgroup_device_acl", false,
&cfg->cgroupDeviceACL) < 0)