linux-kernel - Re: [PATCH] kvm: x86: limit the maximum number of vPMU fixed counters to 3

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Message-ID: <3e849687-67f9-ac53-10ff-2b76d4881de4@intel.com>
Date:   Wed, 8 Jul 2020 22:22:33 +0800
From:   "Xu, Like" <like.xu@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Like Xu <like.xu@...ux.intel.com>, kvm@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kvm: x86: limit the maximum number of vPMU fixed counters
 to 3

On 2020/7/8 19:09, Paolo Bonzini wrote:
> On 08/07/20 09:51, Xu, Like wrote:
>> Kindly ping.
>>
>> I think we may need this patch, as we limit the maximum vPMU version to 2:
>>      eax.split.version_id = min(cap.version, 2);
> I don't think this is a problem.  Are you planning to add support for
> the fourth counter?
Yes, we plan to provide this support on the KVM after fully enabling the fourth
counter (and an accompanying special counter) on the host perf side.

This may require one or two kernel cycles, so I have to prevent it from
being exposed to non-linux guest with this fix. Thanks for your support.

Thanks,
Like Xu
>
> Paolo
>