linux-kernel - Re: [PATCH 0/2] KVM: x86: CPUID tracepoint enhancements

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Message-ID: <f7a1a4a0-7730-93a7-564e-fc4dcad4ee2c@redhat.com>
Date:   Wed, 18 Mar 2020 13:45:01 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com>,
        Jan Kiszka <jan.kiszka@...mens.com>
Subject: Re: [PATCH 0/2] KVM: x86: CPUID tracepoint enhancements

On 17/03/20 20:53, Sean Christopherson wrote:
> Two enhancements to the CPUID tracepoint.  Patch 01 was originally in the
> CPUID ranges series, but I unintentionally dropped it in v2.
> 
> The final output looks like:
> 
>   kvm_cpuid: func 0 idx 0 rax d rbx 68747541 rcx 444d4163 rdx 69746e65, cpuid entry found
>   kvm_cpuid: func d idx 444d4163 rax 0 rbx 0 rcx 0 rdx 0, cpuid entry not found
>   kvm_cpuid: func 80000023 idx 1 rax f rbx 240 rcx 0 rdx 0, cpuid entry not found, used max basic
>   kvm_cpuid: func 80000023 idx 2 rax 100 rbx 240 rcx 0 rdx 0, cpuid entry not found, used max basic
> 
> I also considered appending "exact" to the "found" case, which is more
> directly what Jan suggested, but IMO "found exact" implies there's also a
> "found inexact", which is not true.  AIUI, calling out that KVM is using
> the max basic leaf values is what's really important to avoid confusion.
> 
> Ideally, the function of the max basic leaf would also be displayed, but
> doing that without printing garbage for the other cases is a lot of ugly
> code for marginal value.
> 
> Sean Christopherson (2):
>   KVM: x86: Add requested index to the CPUID tracepoint
>   KVM: x86: Add blurb to CPUID tracepoint when using max basic leaf
>     values
> 
>  arch/x86/kvm/cpuid.c |  9 ++++++---
>  arch/x86/kvm/trace.h | 18 ++++++++++++------
>  2 files changed, 18 insertions(+), 9 deletions(-)
> 

Queued, thanks.

Paolo