From: christoffer.dall@linaro.org (Christoffer Dall)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] arm/arm64: KVM: detect CPU reset on CPU_PM_EXIT
Date: Tue, 25 Feb 2014 06:59:27 -0800 [thread overview]
Message-ID: <20140225145927.GD22447@cbox> (raw)
In-Reply-To: <530C69A8.20800@arm.com>
On Tue, Feb 25, 2014 at 10:00:08AM +0000, Marc Zyngier wrote:
> On 21/02/14 17:12, Christoffer Dall wrote:
> > On Fri, Feb 21, 2014 at 11:46:56AM +0000, Marc Zyngier wrote:
> >> Commit 1fcf7ce0c602 (arm: kvm: implement CPU PM notifier) added
> >> support for CPU power-management, using a cpu_notifier to re-init
> >> KVM on a CPU that entered CPU idle.
> >>
> >> The code assumed that a CPU entering idle would actually be powered
> >> off, loosing its state entierely, and would then need to be
> >> reinitialized. It turns out that this is not always the case, and
> >> some HW performs CPU PM without actually killing the core. In this
> >> case, we try to reinitialize KVM while it is still live. It ends up
> >> badly, as reported by Andre Przywara (using a Calxeda Midway):
> >>
> >> [ 3.663897] Kernel panic - not syncing: unexpected prefetch abort in Hyp mode at: 0x685760
> >> [ 3.663897] unexpected data abort in Hyp mode at: 0xc067d150
> >> [ 3.663897] unexpected HVC/SVC trap in Hyp mode at: 0xc0901dd0
> >>
> >> The trick here is to detect if we've been through a full re-init or
> >> not by looking at HVBAR (VBAR_EL2 on arm64). This involves
> >> implementing the backend for __hyp_get_vectors in the main KVM HYP
> >> code (rather small), and checking the return value against the
> >> default one when the CPU notifier is called on CPU_PM_EXIT.
> >>
> >> Reported-by: Andre Przywara <osp@andrep.de>
> >> Tested-by: Andre Przywara <osp@andrep.de>
> >> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> >> Cc: Rob Herring <rob.herring@linaro.org>
> >> Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
> >> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> >
> > Thanks!
> >
> > Looks good.
>
> Thanks. I'm thinking of pushing this to 3.14 as a fix. Any objection?
>
Nope, go for it.
-Christoffer
prev parent reply other threads:[~2014-02-25 14:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-21 11:46 [PATCH v2] arm/arm64: KVM: detect CPU reset on CPU_PM_EXIT Marc Zyngier
2014-02-21 17:12 ` Christoffer Dall
2014-02-25 10:00 ` Marc Zyngier
2014-02-25 14:59 ` Christoffer Dall [this message]
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