linux-kernel - Re: [PATCH v3 3/7] arm64/kvm: disable access to AMU registers from kvm guests

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Date:   Wed, 12 Feb 2020 16:33:19 +0000
From:   Suzuki Kuruppassery Poulose <suzuki.poulose@....com>
To:     Ionela Voinescu <ionela.voinescu@....com>, catalin.marinas@....com,
        will@...nel.org, mark.rutland@....com, maz@...nel.org,
        sudeep.holla@....com, lukasz.luba@....com,
        valentin.schneider@....com, rjw@...ysocki.net
Cc:     peterz@...radead.org, mingo@...hat.com, vincent.guittot@...aro.org,
        viresh.kumar@...aro.org, linux-arm-kernel@...ts.infradead.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>
Subject: Re: [PATCH v3 3/7] arm64/kvm: disable access to AMU registers from
 kvm guests

On 11/02/2020 18:45, Ionela Voinescu wrote:
> Access to the AMU counters should be disabled by default in kvm guests,
> as information from the counters might reveal activity in other guests
> or activity on the host.
> 
> Therefore, disable access to AMU registers from EL0 and EL1 in kvm
> guests by:
>   - Hiding the presence of the extension in the feature register
>     (SYS_ID_AA64PFR0_EL1) on the VCPU.
>   - Disabling access to the AMU registers before switching to the guest.
>   - Trapping accesses and injecting an undefined instruction into the
>     guest.
> 
> Signed-off-by: Ionela Voinescu <ionela.voinescu@....com>
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: James Morse <james.morse@....com>
> Cc: Julien Thierry <julien.thierry.kdev@...il.com>
> Cc: Suzuki K Poulose <suzuki.poulose@....com>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> ---

Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>