The mpx feature was removed from the corresponding qemu cpu models.
With mpx in the libvirt cpu models, libvirt believes the feature
to be implicitly enabled when creating qemu VMs, while in fact it is
disabled.
This became an issue when commit 94eacd5a5f introduced new vmx-*
features, of which some are dependent on mpx (see "feature_dependencies"
table in qemu target/i386/cpu.c), e.g. vmx-exit-clear-bndcfgs and
vmx-entry-load-bndcfgs. These features cannot be enabled by qemu
without also mpx being enabled, leading to the error message
error: Failed to create domain from testdomain.xml
error: operation failed: guest CPU doesn't match
specification: missing features: mpx,vmx-exit-clear-bndcfgs,
vmx-entry-load-bndcfgs
when trying to create a VM with a "host-model" cpu on a host that
does support mpx and the mentioned vmx-* features:
<domain>
...
<cpu mode='host-model' check='full' />
...
</domain>
Resolve the issue by removing mpx from libvirt's cpu models as well.
Signed-off-by: Tim Wiederhake <twiederh@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Differences from qemu:
* "vmx-ept-uc" (bit 8) and "vmx-ept-wb" (bit 14) are not added to
qemu's list of named features yet, but used in several qemu cpu
models never the less. Add to libvirt regardless.
* "vmx-invvpid-single-context" (bit 41) is erroneously called
"vmx-invept-single-context" in qemu. This is the name of the
feature associated with bit 25 in both libvirt and qemu.
* "vmx-invvpid-single-context-noglobals" (bit 43) is erroneously
called "vmx-invept-single-context-noglobals". Use the correct name.
Signed-off-by: Tim Wiederhake <twiederh@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
While we don't want to aim for the shortest list of disabled features in
the baseline result (it would select a very old model), we want to do so
while looking at any of the input models for which we're trying to
compute a baseline CPU model. Given a set of input models, we always
want to take the least capable one of them (i.e., the one with shortest
list of disabled features) or a better model which is not one of the
input models.
So when considering an input model, we just check whether its list of
disabled features is shorter than the currently best one. When looking
at other models we check both enabled and disabled features while
penalizing disabled features as implemented by the previous patch.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
