linux-kernel - Re: [PATCH v2 3/4] Add support for AMD Core Perf Extension in guest

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Message-ID: <c94fbc32-307f-01b9-564d-cfc68c94648a@amd.com>
Date:   Thu, 16 Nov 2017 11:13:47 -0600
From:   "Natarajan, Janakarajan" <Janakarajan.Natarajan@....com>
To:     Borislav Petkov <bp@...e.de>
Cc:     kvm@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krcmar <rkrcmar@...hat.com>,
        Len Brown <len.brown@...el.com>, Kyle Huey <me@...ehuey.com>,
        Kan Liang <Kan.liang@...el.com>,
        Grzegorz Andrejczuk <grzegorz.andrejczuk@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH v2 3/4] Add support for AMD Core Perf Extension in guest

On 11/15/2017 1:07 PM, Borislav Petkov wrote:
> On Wed, Nov 15, 2017 at 01:04:03PM -0600, Natarajan, Janakarajan wrote:
>> So, when the amd_pmu_init is called, a query to guest_cpuid_family() gives a
>> value of -1.
> And that is because...? And it can be fixed to give the proper guest family I
> presume ...?

Qemu initially creates a vcpu with KVM_CREATE_VCPU which in kvm 
initializes the pmu. Later on
the cpuid is set using KVM_SET_CPUID2 which sets all the cpuid entries 
in kvm and the pmu refresh is called.

>