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Date: Thu, 25 Oct 2018 10:36:37 -0300
From: Eduardo Habkost <ehabkost@redhat.com>
Message-ID: <20181025133637.GH4096@habkost.net>
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Subject: Re: [Qemu-devel] [PATCH v5 2/3] x86: Data structure changes to
 support MSR based features
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To: Robert Hoo <robert.hu@linux.intel.com>
Cc: robert.hu@intel.com, pbonzini@redhat.com, rth@twiddle.net, thomas.lendacky@amd.com, qemu-devel@nongnu.org

On Thu, Oct 25, 2018 at 11:06:59AM +0800, Robert Hoo wrote:
> On Wed, 2018-10-24 at 07:16 -0300, Eduardo Habkost wrote:
[...]
> > > +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0struct {=A0=A0=A0/*CPUID that =
enumerate this MSR*/
> > > +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0FeatureWord cpuid_=
class;
> > > +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0uint32_t=A0=A0=A0=A0=
cpuid_flag;
> > > +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0} cpuid_dep;
> >=20
> > Aren't you going to use this field anywhere?=A0=A0Probably we want to
> > prevent the VM from starting if a bit is set in the feature world
> > but the cpuid_dep bit is not set.
> >=20
> > e.g.:
> > =A0 qemu-system-x86_64 -cpu Skylake-Client,-arch-capabilities,+rsba
> > probably should fail to start.
>=20
> How about in x86_cpu_filter_features() filters the MSR feature word, if
>  its dependent CPUID feature bit is not set?
> The filter results will be record in cpu->filtered_features, and print
> out, like other filtered features.

Sounds good to me.

--=20
Eduardo