On Thu, Sep 01, 2022 at 10:58:04AM +0000, "Huang, Kai" <kai.huang@xxxxxxxxx> wrote: > On Thu, 2022-09-01 at 14:18 +0800, Gao, Chao wrote: > > 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> > > > > Isaku, your signed-off-by is missing. > > > > > Link: https://lore.kernel.org/r/20220216031528.92558-6-chao.gao@xxxxxxxxx > > > --- > > > include/linux/cpuhotplug.h | 2 +- > > > virt/kvm/kvm_main.c | 30 ++++++++++++++++++++++-------- > > > 2 files changed, 23 insertions(+), 9 deletions(-) > > > > > > diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h > > > index f61447913db9..7972bd63e0cb 100644 > > > --- a/include/linux/cpuhotplug.h > > > +++ b/include/linux/cpuhotplug.h > > > @@ -185,7 +185,6 @@ enum cpuhp_state { > > > CPUHP_AP_CSKY_TIMER_STARTING, > > > CPUHP_AP_TI_GP_TIMER_STARTING, > > > CPUHP_AP_HYPERV_TIMER_STARTING, > > > - CPUHP_AP_KVM_STARTING, > > > CPUHP_AP_KVM_ARM_VGIC_INIT_STARTING, > > > CPUHP_AP_KVM_ARM_VGIC_STARTING, > > > CPUHP_AP_KVM_ARM_TIMER_STARTING, > > > > The movement of CPUHP_AP_KVM_STARTING changes the ordering between > > CPUHP_AP_KVM_STARTING and CPUHP_AP_KVM_ARM_* above [1]. We need > > the patch [2] from Marc to avoid breaking ARM. > > > > [1] https://lore.kernel.org/lkml/87sfsq4xy8.wl-maz@xxxxxxxxxx/ > > [2] https://lore.kernel.org/lkml/20220216031528.92558-5-chao.gao@xxxxxxxxx/ > > How about Isaku just to take your series directly (+his SoB) and add additional > patches? Ok will do. Although I hoped to slim it down, I've ended up to take most of it. four out of six. Now why not two more. -- Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
