From: Marc Zyngier <marc.zyngier@arm.com>
To: Wei Huang <wei@redhat.com>
Cc: julien.thierry@arm.com, andre.przywara@arm.com,
suzuki.poulose@arm.com, christoffer.dall@arm.com,
linux-kernel@vger.kernel.org, james.morse@arm.com,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] KVM: arm/arm64: arch_timer: Fix TimerValue TVAL calculation in KVM
Date: Sat, 30 Mar 2019 09:56:14 +0000 [thread overview]
Message-ID: <86wokg65z5.wl-marc.zyngier@arm.com> (raw)
In-Reply-To: <20190329201253.29164-1-wei@redhat.com>
On Fri, 29 Mar 2019 20:12:53 +0000,
Wei Huang <wei@redhat.com> wrote:
>
> Recently the generic timer test of kvm-unit-tests failed to complete
> (stalled) when a physical timer is being used. This issue is caused
> by incorrect update of CNT_CVAL when TimerValue is being accessed,
> introduced by 'Commit 84135d3d18da ("KVM: arm/arm64: consolidate arch
> timer trap handlers")'. According to Arm ARM, the read/write behavior
> of accesses to TimeValue registers is expected to be:
>
> * READ: TimerValue = (CompareValue – (Counter - Offset)
> * WRITE: CompareValue = ((Counter - Offset) + Sign(TimerValue)
>
> This patch fixes the TVAL read/write code path according to the
> specification.
>
> Signed-off-by: Wei Huang <wei@redhat.com>
Huh... Nice catch. I guess I only ran this with a VHE host, where this
code path is unused.
Thanks,
M.
--
Jazz is not dead, it just smell funny.
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prev parent reply other threads:[~2019-03-30 9:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-29 20:12 [PATCH 1/1] KVM: arm/arm64: arch_timer: Fix TimerValue TVAL calculation in KVM Wei Huang
2019-03-30 9:56 ` Marc Zyngier [this message]
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