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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id e19sm468756wme.2.2020.10.05.08.29.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Oct 2020 08:29:49 -0700 (PDT) From: Vitaly Kuznetsov To: Tianjia Zhang Cc: Paolo Bonzini , Sean Christopherson , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: x86: filter guest NX capability for cpuid2 In-Reply-To: <20201005145921.84848-1-tianjia.zhang@linux.alibaba.com> References: <20201005145921.84848-1-tianjia.zhang@linux.alibaba.com> Date: Mon, 05 Oct 2020 17:29:47 +0200 Message-ID: <87ft6s8zdg.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Tianjia Zhang 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 > --- > 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 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