On 02/06/2015 09:11 AM, Geoff Levand wrote: > Hi Takahiro, > > On Mon, 2015-02-02 at 17:18 +0900, AKASHI Takahiro wrote: >> On 01/31/2015 04:48 AM, Geoff Levand wrote: >>> As an initial implementation we can hook into the CPU_DYING_FROZEN >>> notifier sent to hyp_init_cpu_notify(). The longer term solution >>> should use kvm_arch_hardware_enable() and kvm_arch_hardware_disable(). >> >> Are these two different approaches? > > Yes, these are two different solutions, One initial work-around, and a > more involved proper solution. Hooking into the CPU_DYING_FROZEN > notifier would be a initial fix. The proper solution would be to move > the KVM setup to kvm_arch_hardware_enable(), and the shutdown to > kvm_arch_hardware_disable(). > > >> kernel_exec() -> machine_shutdown() -> disable_nonboot_cpu() >> -> _cpu_down() -> cpu_notify_nofail(CPU_DEAD|...) >> >> On the other hand, kvm already has a hook into kvm_arch_hardware_disable(): >> (ignoring kvm_usage_count here) >> kvm_cpu_hotplug(CPU_DYING) -> hardware_disable() >> -> hardware_disable_nolock() -> kvm_arch_hardware_disable() >> >> So it seems that we don't have to add a new hook at hyp_init_cpu_notify() >> if kvm_arch_hardware_disable() is properly implemented. > > Yes, that is correct. But, as above, you would also need to update the > KVM startup to use kvm_arch_hardware_enable(). > >> disable_nonboot_cpu() will not inovke cpu hotplug on *boot* cpu, and >> we should handle it in a separate way though. > > IIRC, the secondary cpus go through PSCI on shutdown, and that path > is working OK. Maybe I am mistaken though. If so, why should we add a hook at hyp_init_cpu_notify() as initial work-around? > The primary cpu shutdown (hyp stubs restored) is what is missing. The > primary cpu goes through cpu_soft_restart(), and that is what is > currently failing. Yeah, we will call teardown function manually in soft_restart(); -Takahiro AKASHI > > -Geoff >
