From: osp@andrep.de (Andre Przywara)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm/arm64: KVM: detect CPU reset on CPU_PM_EXIT
Date: Thu, 20 Feb 2014 23:35:43 +0100 [thread overview]
Message-ID: <20140220233543.1836e2d5@slackpad> (raw)
In-Reply-To: <1392910014-15495-1-git-send-email-marc.zyngier@arm.com>
On Thu, 20 Feb 2014 15:26:54 +0000
Marc Zyngier <marc.zyngier@arm.com> wrote:
> Commit 1fcf7ce0c602 (arm: kvm: implement CPU PM notifier) added
> support for CPU power-management, using a cpu_nofigier 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 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>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Rob Herring <rob.herring@linaro.org>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Tested-by: Andre Przywara <osp@andrep.de>
(there seems to be a typo in the second line of the commit message)
Marc,
thanks a lot for this quick and perfectly working patch! I still
believe it is actually the firmware that needs to be fixed, but this is
rather unlikely in this special case ...
Regards,
Andre.
> ---
> arch/arm/kvm/arm.c | 3 ++-
> arch/arm/kvm/interrupts.S | 7 ++++++-
> arch/arm64/kvm/hyp.S | 9 +++++++--
> 3 files changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 1d8248e..bd18bb8 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -878,7 +878,8 @@ static int hyp_init_cpu_pm_notifier(struct
> notifier_block *self, unsigned long cmd,
> void *v)
> {
> - if (cmd == CPU_PM_EXIT) {
> + if (cmd == CPU_PM_EXIT &&
> + __hyp_get_vectors() == hyp_default_vectors) {
> cpu_init_hyp_mode(NULL);
> return NOTIFY_OK;
> }
> diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
> index ddc1553..9b0ff68 100644
> --- a/arch/arm/kvm/interrupts.S
> +++ b/arch/arm/kvm/interrupts.S
> @@ -363,6 +363,11 @@ hyp_hvc:
> host_switch_to_hyp:
> pop {r0, r1, r2}
>
> + /* Check for __hyp_get_vectors */
> + cmp r0, #-1
> + mrceq p15, 4, r0, c12, c0, 0 @ get HVBAR
> + beq 1f
> +
> push {lr}
> mrs lr, SPSR
> push {lr}
> @@ -378,7 +383,7 @@ THUMB( orr lr, #1)
> pop {lr}
> msr SPSR_csxf, lr
> pop {lr}
> - eret
> +1: eret
>
> guest_trap:
> load_vcpu @ Load VCPU pointer to r0
> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
> index 3b47c36..f1cbabe 100644
> --- a/arch/arm64/kvm/hyp.S
> +++ b/arch/arm64/kvm/hyp.S
> @@ -737,7 +737,12 @@
> el1_sync: // Guest trapped
> into EL2 pop x2, x3 pop x0, x1
>
> - push lr, xzr
> + /* Check for __hyp_get_vectors */
> + cbnz x0, 1f
> + mrs x0, vbar_el2
> + b 2f
> +
> +1: push lr, xzr
>
> /*
> * Compute the function address in EL2, and shuffle the
> parameters. @@ -750,7 +755,7 @@
> el1_sync: // Guest trapped
> into EL2 blr lr
> pop lr, xzr
> - eret
> +2: eret
>
> el1_trap:
> /*
next prev parent reply other threads:[~2014-02-20 22:35 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-20 15:26 [PATCH] arm/arm64: KVM: detect CPU reset on CPU_PM_EXIT Marc Zyngier
2014-02-20 22:35 ` Andre Przywara [this message]
2014-02-21 1:24 ` Christoffer Dall
2014-02-21 11:20 ` Marc Zyngier
2014-02-21 14:39 ` Lorenzo Pieralisi
2014-02-21 1:23 ` Christoffer Dall
2014-02-21 11:43 ` Marc Zyngier
2014-02-26 18:47 Marc Zyngier
2014-02-26 18:47 ` Marc Zyngier
2014-02-26 20:32 ` Paolo Bonzini
2014-02-26 20:32 ` Paolo Bonzini
2014-02-27 18:27 ` Paolo Bonzini
2014-02-27 18:27 ` Paolo Bonzini
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