From: Vladimir Murzin Date: Mon, 22 Sep 2014 14:52:48 +0000 (+0100) Subject: arm: kvm: fix CPU hotplug X-Git-Tag: firefly_0821_release~3680^2~36^2~16^2^2~8 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2dc5e2cf90915059fbc39ef380605aef6adaef47;p=firefly-linux-kernel-4.4.55.git arm: kvm: fix CPU hotplug On some platforms with no power management capabilities, the hotplug implementation is allowed to return from a smp_ops.cpu_die() call as a function return. Upon a CPU onlining event, the KVM CPU notifier tries to reinstall the hyp stub, which fails on platform where no reset took place following a hotplug event, with the message: CPU1: smp_ops.cpu_die() returned, trying to resuscitate CPU1: Booted secondary processor Kernel panic - not syncing: unexpected prefetch abort in Hyp mode at: 0x80409540 unexpected data abort in Hyp mode at: 0x80401fe8 unexpected HVC/SVC trap in Hyp mode at: 0x805c6170 since KVM code is trying to reinstall the stub on a system where it is already configured. To prevent this issue, this patch adds a check in the KVM hotplug notifier that detects if the HYP stub really needs re-installing when a CPU is onlined and skips the installation call if the stub is already in place, which means that the CPU has not been reset. Signed-off-by: Vladimir Murzin Acked-by: Lorenzo Pieralisi Acked-by: Marc Zyngier Signed-off-by: Christoffer Dall (cherry picked from commit 37a34ac1d4775aafbc73b9db53c7daebbbc67e6a) Signed-off-by: Christoffer Dall --- diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 15111ca6fe30..d0c8ee654bbf 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -808,7 +808,8 @@ static int hyp_init_cpu_notify(struct notifier_block *self, switch (action) { case CPU_STARTING: case CPU_STARTING_FROZEN: - cpu_init_hyp_mode(NULL); + if (__hyp_get_vectors() == hyp_default_vectors) + cpu_init_hyp_mode(NULL); break; }