On 1/17/19 4:37 PM, Laine Stump wrote: > When commit 361c8dc17 added support for hotplugging the i6300esb > watchdog device (first in libvirt-3.9.0), it accidentally contstructed > the commandline for the device_add command before allocating a PCI > address for the device. With no PCI address specified in the command, > the watchdog would simply be placed at the lowest unused PCI slot. > > On a 440fx guest, this doesn't cause a problem, because libvirt's PCI > address allocation algorithm would most likely give the same address > anyway (usually a slot on pci-root), so nobody noticed the omission of > address from the command. > > But on a Q35 guest, the lowest unused PCI slot is on pcie-root, which > doesn't support hotplug; libvirt knows enough to assign a PCI address > that is on a pcie-to-pci-bridge (because its slots *do* support > hotplug), but qemu doesn't, so if there is no PCI address in the > command, qemu just tries to plug the new device into pcie-root, and > fails because it doesn't support hotplug, e.g.: > > error: Failed to attach device from watchdog.xml > error: internal error: unable to execute QEMU command 'device_add': > Bus 'pcie.0' does not support hotplugging > > The solution is simply to build the command string after assigning a > PCI address, not before. > > Resolves: https://bugzilla.redhat.com/1666559 > Signed-off-by: Laine Stump <laine@xxxxxxxxx> > --- > src/qemu/qemu_hotplug.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > Reviewed-by: John Ferlan <jferlan@xxxxxxxxxx> John -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
