linux-kernel - Re: [PATCH v9 06/12] KVM: x86: Add Intel Processor Trace virtualization mode

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Message-ID: <20180607132638.snnnt5ecwisfgkmy@um.fi.intel.com>
Date:   Thu, 7 Jun 2018 16:26:38 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Luwei Kang <luwei.kang@...el.com>
Cc:     kvm@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, chao.p.peng@...ux.intel.com,
        thomas.lendacky@....com, bp@...e.de, Kan.liang@...el.com,
        Janakarajan.Natarajan@....com, dwmw@...zon.co.uk,
        linux-kernel@...r.kernel.org, alexander.shishkin@...ux.intel.com,
        peterz@...radead.org, mathieu.poirier@...aro.org,
        kstewart@...uxfoundation.org, gregkh@...uxfoundation.org,
        pbonzini@...hat.com, rkrcmar@...hat.com, david@...hat.com,
        bsd@...hat.com, yu.c.zhang@...ux.intel.com, joro@...tes.org
Subject: Re: [PATCH v9 06/12] KVM: x86: Add Intel Processor Trace
 virtualization mode

On Tue, May 22, 2018 at 12:52:09PM +0800, Luwei Kang wrote:
> From: Chao Peng <chao.p.peng@...ux.intel.com>
> 
> Intel PT virtualization can be work in one of 2 possible modes:
> a. system-wide: trace both host and guest and output to host buffer;
> b. host-guest: trace host/guest simultaneous and output to their
>    respective buffer.

I think we discussed this before. That's not the choice that the user
needs to make. The only choice that I see is what happens if the guest
wants to use PT while it's already in use by the host. Otherwise, each
of them gets to use PT as they would.

Regards,
--
Alex