Certain hypervisors (like qemu/kvm) map the PCI bar(s) on
the host when doing device passthrough. This can lead to a race
condition where the hypervisor is still cleaning up the device while
libvirt is trying to re-attach it to the host device driver. To avoid
this situation, we look through /proc/iomem, and if the hypervisor is
still holding onto the bar (denoted by the string in the matcher variable),
then we can wait around a bit for that to clear up.
v2: Thanks to review by DV, make sure we wait the full timeout per-device
Signed-off-by: Chris Lalancette <clalance@redhat.com>
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