linux-kernel - Re: [PATCH 2/6] kvm: x86: drop read_tsc

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Date:   Wed, 21 Sep 2016 08:19:54 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Luiz Capitulino <lcapitulino@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Radim Krčmář <rkrcmar@...hat.com>,
        rostedt@...dmis.org, mhiramat@...nel.org, mtosatti@...hat.com
Subject: Re: [PATCH 2/6] kvm: x86: drop read_tsc_offset()

Doesn't that assume you can run the merge program in L1?

On Mon, Sep 19, 2016 at 10:37 PM, Paolo Bonzini <pbonzini@...hat.com> wrote:
>
>
> On 20/09/2016 00:18, Jim Mattson wrote:
>> Hmmm. Yes, I think it does. With this patch series,
>> vcpu->arch.tsc_offset appears to contain L1's TSC offset (perhaps
>> making vmx->nested.vmcs01_tsc_offset redundant).
>>
>> However, this unfortunately limits the newly added functionality to
>> merging host and *L1* guest traces. It doesn't work with L2 (or
>> deeper) guests. Or perhaps I'm missing something?
>
> You can merge L1/L2 first and then host/L1.
>
> Paolo