linux-kernel - Re: [PATCH] KVM: x86: Fix perfctr WRMSR for running counters

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Message-ID: <CALMp9eRfeFFb6n22Uf4R2Pf8WW7BVLX_Vuf04WFwiMtrk14Y-Q@mail.gmail.com>
Date:   Tue, 28 Jan 2020 13:59:28 -0800
From:   Jim Mattson <jmattson@...gle.com>
To:     Eric Hankland <ehankland@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Peter Shier <pshier@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>
Subject: Re: [PATCH] KVM: x86: Fix perfctr WRMSR for running counters

On Mon, Jan 27, 2020 at 1:23 PM Eric Hankland <ehankland@...gle.com> wrote:
>
> Correct the logic in intel_pmu_set_msr() for fixed and general purpose
> counters. This was recently changed to set pmc->counter without taking
> in to account the value of pmc_read_counter() which will be incorrect if
> the counter is currently running and non-zero; this changes back to the
> old logic which accounted for the value of currently running counters.
>
> Signed-off-by: Eric Hankland <ehankland@...gle.com>

Fixes: 2924b52117b2 ("KVM: x86/pmu: do not mask the value that is
written to fixed PMUs")

Reviewed-by: Jim Mattson <jmattson@...gle.com>