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SubjectRe: [PATCH] KVM: x86: filter guest NX capability for cpuid2
Date
Tianjia Zhang <tianjia.zhang@linux.alibaba.com> writes:

> Original KVM_SET_CPUID has removed NX on non-NX hosts as it did
> before. but KVM_SET_CPUID2 does not. The two should be consistent.
>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> ---
> arch/x86/kvm/cpuid.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 3fd6eec202d7..3e7ba2b11acb 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -257,6 +257,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
> goto out;
> }
>
> + cpuid_fix_nx_cap(vcpu);
> kvm_update_cpuid_runtime(vcpu);
> kvm_vcpu_after_set_cpuid(vcpu);
> out:

I stumbled upon this too and came to the conclusion this is
intentional, e.g. see this:

commit 0771671749b59a507b6da4efb931c44d9691e248
Author: Dan Kenigsberg <danken@qumranet.com>
Date: Wed Nov 21 17:10:04 2007 +0200

KVM: Enhance guest cpuid management

...

[avi: fix original KVM_SET_CPUID not removing nx on non-nx hosts as it did
before]

but this is a very, very old story.

--
Vitaly

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