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Subject: Re: [Qemu-devel] [PATCH 4/4] kvm: Trim cpu features not supported
	by kvm
From: Mark McLoughlin <markmc@redhat.com>
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Date: Tue, 12 May 2009 12:52:34 +0100
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To: Avi Kivity <avi@redhat.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org

On Sun, 2009-05-03 at 17:04 +0300, Avi Kivity wrote:
> Remove cpu features that are not supported by kvm from the cpuid features
> reported to the guest.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
....
> @@ -1699,5 +1714,20 @@ CPUX86State *cpu_x86_init(const char *cpu_model)
>  
>      qemu_init_vcpu(env);
>  
> +    if (kvm_enabled()) {
> +        kvm_trim_features(&env->cpuid_features,
> +                          kvm_arch_get_supported_cpuid(env, 1, R_EDX),
> +                          feature_name);

This isn't work in qemu.git because the features are only queried from
qemu_init_vcpu() (see kvm_arch_init_vcpu())

The obvious fix is to move qemu_init_vcpu() after the feature trimming,
but that requires us to split env->kvm_state initialization out of
kvm_init_vcpu()

Also, it works in qemu-kvm.git, but only because actually call
kvm_qemu_init_env() twice - once before feature trimming and once after.

Cheers,
Mark.