Since its release of 2.4.0 qemu is able to enable System
Management Module in the firmware, or disable it. We should
expose this capability in the XML. Unfortunately, there's no good
way to determine whether the binary we are talking to supports
it. I mean, if qemu's run with real machine type, the smm
attribute can be seen in 'qom-list /machine' output. But it's not
there when qemu's run with -M none. Therefore we're stuck with
version based check.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Check whether QEMU supports -device intel-iommu
Note that the presence of this option does not mean that it's
usable because of a bug in earlier QEMU versions, but it's
better than nothing.
https://bugzilla.redhat.com/show_bug.cgi?id=1235580
The only QEMU versions that don't have such capability are <0.12,
which we no longer support anyway.
Additionally, this solves the issue of some QEMU binaries being
reported as not having such capability just because they lacked
the {kvm-}pci-assign QMP object.
