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? -- Thanks, -Kai
