multiple vms with same PCI passthrough

[Daniel Black]

In attempting to isolate vfio-pci problems between two different guest
instances, the creation of a second guest (with existing guest shutdown)
resulted in:.

Aug 09 12:43:23 grit libvirtd[6716]: internal error: Device 0000:01:00.3 is
already in use
Aug 09 12:43:23 grit libvirtd[6716]: internal error: Device 0000:01:00.3 is
already in use
Aug 09 12:43:23 grit libvirtd[6716]: Failed to allocate PCI device list:
internal error: Device 0000:01:00.3 is already in use

Compiled against library: libvirt 6.1.0
Using library: libvirt 6.1.0
Using API: QEMU 6.1.0
Running hypervisor: QEMU 4.2.1
(fc32 default install)

The upstream code seems  also to test definitions rather than active uses
of the PCI device.

My potentially naive patch to correct this (but not the failing test cases)
would be:

diff --git a/src/util/virpci.c b/src/util/virpci.c
index 47c671daa0..a00c5e6f44 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -1597,7 +1597,7 @@ int
 virPCIDeviceListAdd(virPCIDeviceListPtr list,
                     virPCIDevicePtr dev)
 {
-    if (virPCIDeviceListFind(list, dev)) {
+    if (virPCIDeviceBusContainsActiveDevices(dev, list)) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("Device %s is already in use"), dev->name);
         return -1;

Is this too simplistic or undesirable a feature request/implementation?

I'd be more than grateful if someone carries this through as I'm unsure
when I may get time for this.
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