From: Alexandru Elisei <alexandru.elisei@arm.com>
To: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com,
sumit.garg@linaro.org, maz@kernel.org, swboyd@chromium.org,
catalin.marinas@arm.com, Julien Thierry <julien.thierry@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Marc Zyngier <marc.zyngier@arm.com>,
Will Deacon <will.deacon@arm.com>,
James Morse <james.morse@arm.com>,
Suzuki K Pouloze <suzuki.poulose@arm.com>,
kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v7 5/7] KVM: arm64: pmu: Make overflow handler NMI safe
Date: Wed, 30 Sep 2020 13:37:49 +0100 [thread overview]
Message-ID: <6b1ecdef-3a42-c428-2309-753b1470e3de@arm.com> (raw)
In-Reply-To: <20200928175725.GB11792@willie-the-truck>
Hi Will,
On 9/28/20 6:57 PM, Will Deacon wrote:
> On Thu, Sep 24, 2020 at 12:07:04PM +0100, Alexandru Elisei wrote:
>> From: Julien Thierry <julien.thierry@arm.com>
>>
>> kvm_vcpu_kick() is not NMI safe. When the overflow handler is called from
>> NMI context, defer waking the vcpu to an irq_work queue.
>>
>> A vcpu can be freed while it's not running by kvm_destroy_vm(). Prevent
>> running the irq_work for a non-existent vcpu by calling irq_work_sync() on
>> the PMU destroy path.
>>
>> Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
>> Cc: Marc Zyngier <marc.zyngier@arm.com>
>> Cc: Will Deacon <will.deacon@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: James Morse <james.morse@arm.com>
>> Cc: Suzuki K Pouloze <suzuki.poulose@arm.com>
>> Cc: kvm@vger.kernel.org
>> Cc: kvmarm@lists.cs.columbia.edu
>> Signed-off-by: Julien Thierry <julien.thierry@arm.com>
>> Tested-by: Sumit Garg <sumit.garg@linaro.org> (Developerbox)
>> [Alexandru E.: Added irq_work_sync()]
>> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
>> ---
>> I suggested in v6 that I will add an irq_work_sync() to
>> kvm_pmu_vcpu_reset(). It turns out it's not necessary: a vcpu reset is done
>> by the vcpu being reset with interrupts enabled, which means all the work
>> has had a chance to run before the reset takes place.
> I don't understand this ^^
Marc had the same comment, I replied in his email. I thought about it and you're
right, it doesn't make much sense.
>
> But the patch itself looks good, so I'm going to queue this lot anyway!
Thank you for picking up the series!
Thanks,
Alex
next prev parent reply other threads:[~2020-09-30 12:36 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 11:06 [PATCH v7 0/7] arm_pmu: Use NMI for perf interrupt Alexandru Elisei
2020-09-24 11:07 ` [PATCH v7 1/7] arm64: perf: Add missing ISB in armv8pmu_enable_counter() Alexandru Elisei
2020-09-24 11:07 ` [PATCH v7 2/7] arm64: perf: Avoid PMXEV* indirection Alexandru Elisei
2020-09-24 11:07 ` [PATCH v7 3/7] arm64: perf: Remove PMU locking Alexandru Elisei
2020-09-24 11:07 ` [PATCH v7 4/7] arm64: perf: Defer irq_work to IPI_IRQ_WORK Alexandru Elisei
2020-09-24 11:07 ` [PATCH v7 5/7] KVM: arm64: pmu: Make overflow handler NMI safe Alexandru Elisei
2020-09-28 17:57 ` Will Deacon
2020-09-30 12:37 ` Alexandru Elisei [this message]
2020-09-29 8:11 ` Marc Zyngier
2020-09-30 11:46 ` Alexandru Elisei
2020-09-24 11:07 ` [PATCH v7 6/7] arm_pmu: Introduce pmu_irq_ops Alexandru Elisei
2020-09-24 11:07 ` [PATCH v7 7/7] arm_pmu: arm64: Use NMIs for PMU Alexandru Elisei
2020-09-28 22:13 ` [PATCH v7 0/7] arm_pmu: Use NMI for perf interrupt Will Deacon
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