linux-kernel - Re: [PATCH v3 1/1] KVM: ARM64: Fix the issues when guest PMCCFILTR is configured

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Message-ID: <20161117133039.GH22855@arm.com>
Date:   Thu, 17 Nov 2016 13:30:39 +0000
From:   Will Deacon <will.deacon@....com>
To:     Wei Huang <wei@...hat.com>
Cc:     kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
        shannon.zhao@...aro.org, kvm@...r.kernel.org, marc.zyngier@....com,
        christoffer.dall@...aro.org, drjones@...hat.com,
        cov@...eaurora.org, mark.rutland@....com, catalin.marinas@....com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/1] KVM: ARM64: Fix the issues when guest PMCCFILTR
 is configured

On Wed, Nov 16, 2016 at 11:09:20AM -0600, Wei Huang wrote:
> KVM calls kvm_pmu_set_counter_event_type() when PMCCFILTR is configured.
> But this function can't deals with PMCCFILTR correctly because the evtCount
> bits of PMCCFILTR, which is reserved 0, conflits with the SW_INCR event
> type of other PMXEVTYPER<n> registers. To fix it, when eventsel == 0, this
> function shouldn't return immediately; instead it needs to check further
> if select_idx is ARMV8_PMU_CYCLE_IDX.
> 
> Another issue is that KVM shouldn't copy the eventsel bits of PMCCFILTER
> blindly to attr.config. Instead it ought to convert the request to the
> "cpu cycle" event type (i.e. 0x11).
> 
> To support this patch and to prevent duplicated definitions, a limited
> set of ARMv8 perf event types were relocated from perf_event.c to
> asm/perf_event.h.
> 
> Signed-off-by: Wei Huang <wei@...hat.com>
> ---
>  arch/arm64/include/asm/perf_event.h | 10 +++++++++-
>  arch/arm64/kernel/perf_event.c      | 10 +---------
>  virt/kvm/arm/pmu.c                  |  8 +++++---
>  3 files changed, 15 insertions(+), 13 deletions(-)

Acked-by: Will Deacon <will.deacon@....com>

I'm assuming this will go via kvm-arm.

Will