Re: [PATCH 1/2] KVM: x86: disable MPX if host did not enable MPX XSAVE features

From	Paolo Bonzini <pbonzini@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/2] KVM: x86: disable MPX if host did not enable MPX XSAVE features
Date	2016-03-24 14:10 +0100
Message-ID	<rgdbr-34K-1@gated-at.bofh.it> (permalink)
References	<raojg-hv-9@gated-at.bofh.it> <raojg-hv-7@gated-at.bofh.it> <rbucW-69h-13@gated-at.bofh.it> <rbucW-69h-11@gated-at.bofh.it> <rgdbr-34K-3@gated-at.bofh.it>
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On 24/03/2016 14:06, Yang Zhang wrote:
> 
> I mean why not keep the old way that only activate the eager_fpu while
> guest sees the MPX bit in CPUID, like:
> 
> vcpu->arch.eager_fpu = use_eager_fpu() && guest_cpuid_has_mpx(vcpu);

If the host uses eager FPU you can assume that it's faster than lazy FPU.

Paolo

> Besides, vmx_fpu_activate is called when do vcpu_reset. So it seems no
> need to call fpu_activate() here again.

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Re: [PATCH 1/2] KVM: x86: disable MPX if host did not enable MPX  XSAVE features Paolo Bonzini <pbonzini@redhat.com> - 2016-03-24 14:10 +0100

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