From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753797AbcHRRWN (ORCPT ); Thu, 18 Aug 2016 13:22:13 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:36387 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751041AbcHRRVv (ORCPT ); Thu, 18 Aug 2016 13:21:51 -0400 Subject: Re: [PATCH 14/16] x86: kvm: Convert to hotplug state machine To: Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org References: <20160818125731.27256-1-bigeasy@linutronix.de> <20160818125731.27256-15-bigeasy@linutronix.de> Cc: Peter Zijlstra , Ingo Molnar , rt@linutronix.de, Gleb Natapov , kvm@vger.kernel.org From: Paolo Bonzini Message-ID: <8912020e-bf85-67b0-f401-538893c4ca5e@redhat.com> Date: Thu, 18 Aug 2016 19:06:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160818125731.27256-15-bigeasy@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/08/2016 14:57, Sebastian Andrzej Siewior wrote: > Install the callbacks via the state machine. The online & down callbacks are > invoke on the target CPU so we can avoid using smp_call_function_single(). > local_irq_disable() is used because smp_call_function_single() used to invoke > the function with interrupts disabled. > > Cc: Gleb Natapov > Cc: Paolo Bonzini > Cc: kvm@vger.kernel.org > Signed-off-by: Sebastian Andrzej Siewior > --- > arch/x86/kernel/kvm.c | 42 +++++++++++++++--------------------------- > 1 file changed, 15 insertions(+), 27 deletions(-) > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index 1726c4c12336..d1fcb2d3c976 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -423,12 +423,7 @@ static void __init kvm_smp_prepare_boot_cpu(void) > kvm_spinlock_init(); > } > > -static void kvm_guest_cpu_online(void *dummy) > -{ > - kvm_guest_cpu_init(); > -} > - > -static void kvm_guest_cpu_offline(void *dummy) > +static void kvm_guest_cpu_offline(void) > { > kvm_disable_steal_time(); > if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) > @@ -437,29 +432,21 @@ static void kvm_guest_cpu_offline(void *dummy) > apf_task_wake_all(); > } > > -static int kvm_cpu_notify(struct notifier_block *self, unsigned long action, > - void *hcpu) > +static int kvm_cpu_online(unsigned int cpu) > { > - int cpu = (unsigned long)hcpu; > - switch (action) { > - case CPU_ONLINE: > - case CPU_DOWN_FAILED: > - case CPU_ONLINE_FROZEN: > - smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0); > - break; > - case CPU_DOWN_PREPARE: > - case CPU_DOWN_PREPARE_FROZEN: > - smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1); > - break; > - default: > - break; > - } > - return NOTIFY_OK; > + local_irq_disable(); > + kvm_guest_cpu_init(); > + local_irq_enable(); > + return 0; > } > > -static struct notifier_block kvm_cpu_notifier = { > - .notifier_call = kvm_cpu_notify, > -}; > +static int kvm_cpu_down_prepare(unsigned int cpu) > +{ > + local_irq_disable(); > + kvm_guest_cpu_offline(); > + local_irq_enable(); > + return 0; > +} > #endif > > static void __init kvm_apf_trap_init(void) > @@ -494,7 +481,8 @@ void __init kvm_guest_init(void) > > #ifdef CONFIG_SMP > smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; > - register_cpu_notifier(&kvm_cpu_notifier); > + cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "X86_KVM_ONLINE", > + kvm_cpu_online, kvm_cpu_down_prepare); > #else > kvm_guest_cpu_init(); > #endif > Reviewed-by: Paolo Bonzini