linux-kernel - Re: [PATCH v2 48/66] KVM: x86: Remove stateful CPUID handling

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Date:   Tue, 3 Mar 2020 11:23:18 -0800
From:   Jim Mattson <jmattson@...gle.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>, kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Xiaoyao Li <xiaoyao.li@...el.com>
Subject: Re: [PATCH v2 48/66] KVM: x86: Remove stateful CPUID handling

On Mon, Mar 2, 2020 at 3:57 PM Sean Christopherson
<sean.j.christopherson@...el.com> wrote:

> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index b5dce17c070f..49527dbcc90c 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -495,25 +495,16 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
>                  * time, with the least-significant byte in EAX enumerating the
>                  * number of times software should do CPUID(2, 0).
>                  *
> -                * Modern CPUs (quite likely every CPU KVM has *ever* run on)
> -                * are less idiotic.  Intel's SDM states that EAX & 0xff "will
> -                * always return 01H. Software should ignore this value and not
> +                * Modern CPUs, i.e. every CPU KVM has *ever* run on are less

Nit: missing comma after "run on."

Reviewed-by: Jim Mattson <jmattson@...gle.com>