Re: [Qemu-devel] [PATCH v3 5/6] target-i386: Don't enable nested VMX by default

[Paolo Bonzini]

> Here I'm less certain what the best approach is. As you point out,
> there's an inconsistency that I agree should be fixed. I wonder however
> whether an approach similar to 3/6 for KVM only would be better? I.e.,
> have VMX as a sometimes-KVM-supported feature be listed in the model and
> filter it out for accel=kvm so that -cpu enforce works, but let
> accel=tcg fail with features not implemented.

This would mean that -cpu coreduo,enforce doesn't work on TCG, but -cpu
Nehalem,enforce works.  This does not make much sense to me.

In fact, I would even omit the x86_cpu_compat_set_features altogether.
The inclusion of vmx in these models was a mistake, and nested VMX is
not really useful with anything but "-cpu host" because there are too
many capabilities communicated via MSRs rather than CPUID.

Paolo