linux-kernel - Re: [PATCH v2 34/49] KVM: x86: Advertise HYPERVISOR in KVM_GET_SUPPORTED

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Message-ID: <6f17f9620409dbfaa153332b934563405f5fab00.camel@redhat.com>
Date: Thu, 04 Jul 2024 22:04:28 -0400
From: Maxim Levitsky <mlevitsk@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini
 <pbonzini@...hat.com>,  Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, Hou Wenlong
 <houwenlong.hwl@...group.com>, Kechen Lu <kechenl@...dia.com>, Oliver Upton
 <oliver.upton@...ux.dev>, Binbin Wu <binbin.wu@...ux.intel.com>, Yang
 Weijiang <weijiang.yang@...el.com>, Robert Hoo <robert.hoo.linux@...il.com>
Subject: Re: [PATCH v2 34/49] KVM: x86: Advertise HYPERVISOR in
 KVM_GET_SUPPORTED_CPUID

On Fri, 2024-05-17 at 10:39 -0700, Sean Christopherson wrote:
> Unconditionally advertise "support" for the HYPERVISOR feature in CPUID,
> as the flag simply communicates to the guest that's it's running under a
> hypervisor.
> 
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/cpuid.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index d1f427284ccc..de898d571faa 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -681,7 +681,8 @@ void kvm_set_cpu_caps(void)
>  		F(PCID) | 0 /* Reserved, DCA */ | F(XMM4_1) |
>  		F(XMM4_2) | EMUL_F(X2APIC) | F(MOVBE) | F(POPCNT) |
>  		EMUL_F(TSC_DEADLINE_TIMER) | F(AES) | F(XSAVE) |
> -		0 /* OSXSAVE */ | F(AVX) | F(F16C) | F(RDRAND)
> +		0 /* OSXSAVE */ | F(AVX) | F(F16C) | F(RDRAND) |
> +		EMUL_F(HYPERVISOR)
>  	);
>  
>  	kvm_cpu_cap_init(CPUID_1_EDX,

This makes sense.

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky