arm/arm64: KVM: detect CPU reset on CPU_PM_EXIT
Commit 1fcf7ce0 (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: NAndre Przywara <osp@andrep.de> Tested-by: NAndre Przywara <osp@andrep.de> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Rob Herring <rob.herring@linaro.org> Acked-by: NChristoffer Dall <christoffer.dall@linaro.org> Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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