Re: [libvirt] [PATCH 3/4] conf: log error when incorrect PCI root controller is added to domain

libvirt may automatically add a pci-root or pcie-root controller to a domain, depending on the arch/machinetype, and it hopefully always makes the right decision about which to add (since in all cases these controllers are an implicit part of the virtual machine). But it's always possible that someone will create a config that explicitly supplies the wrong type of PCI controller for the selected machinetype. In the past that would lead to an error later when libvirt was trying to assign addresses to other devices, for example: XML error: PCI bus is not compatible with the device at 0000:00:02.0. Device requires a PCI Express slot, which is not provided by bus 0000:00 (that's the error message that appears if you replace the pcie-root controller in a Q35 domain with a pci-root controller). This patch adds a check at the same place that the implicit controllers are added (to ensure that the same logic is used to check which type of pci root is correct). If a pci controller with index='0' is already present, we verify that it is of the model that we would have otherwise added automatically; if not, an error is logged: The PCI controller with index='0' must be " model='pcie-root' for this machine type, " but model='pci-root' was found instead. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1004602 --- src/qemu/qemu_domain.c | 47 +++++++++++++++++++++++++++++++++++------------ 1 file changed, 35 insertions(+), 12 deletions(-)