On Tue, Aug 30, 2022 at 05:01:20AM -0700, isaku.yamahata@xxxxxxxxx wrote: >From: Chao Gao <chao.gao@xxxxxxxxx> > >The CPU STARTING section doesn't allow callbacks to fail. Move KVM's >hotplug callback to ONLINE section so that it can abort onlining a CPU in >certain cases to avoid potentially breaking VMs running on existing CPUs. >For example, when kvm fails to enable hardware virtualization on the >hotplugged CPU. > >Place KVM's hotplug state before CPUHP_AP_SCHED_WAIT_EMPTY as it ensures >when offlining a CPU, all user tasks and non-pinned kernel tasks have left >the CPU, i.e. there cannot be a vCPU task around. So, it is safe for KVM's >CPU offline callback to disable hardware virtualization at that point. >Likewise, KVM's online callback can enable hardware virtualization before >any vCPU task gets a chance to run on hotplugged CPUs. > >KVM's CPU hotplug callbacks are renamed as well. > >Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> >Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx> >Link: https://lore.kernel.org/r/20220216031528.92558-6-chao.gao@xxxxxxxxx Note that Sean gave his Reviewed-by for KVM changes. https://lore.kernel.org/all/Yg%2FmxKrB5ZoRBIG+@xxxxxxxxxx/
