Up until a while ago, libvirt would automatically add a legacy
PCI controllers combo (dmi-to-pci-bridge + pci-bridge) to any
PCIe machine type (x86_64/q35 and aarch64/virt).
As a result, a number of input and output files in the test
suite ended up containing the legacy PCI controllers, even
though they are not needed or in any way relevant to the
feature being tested.
Get rid of most of the occurrences. Most of the time, this
just means removing the controllers from the input file and
regenerating the output files; in a few instances, some
minor tweaking is performed on the input file, most notably
removing the memory balloon: as memory balloon support was
not the scope of the test being changed, there is no loss
of test coverage from doing so.
Several occurrences of the legacy PCI controllers remain in
the test suite, both because removing their usage would have
required even more tweaking, and because we still want to
have coverage of this perfectly valid combination.
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
