From patchwork Wed Feb 9 07:41:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chao Gao X-Patchwork-Id: 12739736 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E533C433F5 for ; Wed, 9 Feb 2022 07:43:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239735AbiBIHmz (ORCPT ); Wed, 9 Feb 2022 02:42:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40162 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239052AbiBIHm0 (ORCPT ); Wed, 9 Feb 2022 02:42:26 -0500 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F269C05CB8C; Tue, 8 Feb 2022 23:42:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644392550; x=1675928550; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=7oQ6ZbaKyf2t7+Jw+hgZ1jRXBsKBASTYCG0C9ywN06s=; b=HXM8DYgIgu+HrFUd0SQ/W/J2jWWah/qW4cZV1v9IwuCvgkddlLoet0wq s/B+zBwvdmLF5UYMOMix13Ko3YcDoIs8DivM373dCv39/geZ3Ib48fBhD R0GLY8jcOQ7i3L4L6IMMc5U0tWYu1ITR4f2y72R/lteFrXCedWRRJHtEy Fb3bDsf+dzT4wxaxiA4mFNkQQFrHJzxQAit5A9Q8LZ5LwrAv984Dvs1dz WNEdW2MXj1kdvM7I8g9cyarjvvF1W1ST3JJbmEdGE4QKZ6xAPWlpojG86 dE1h1PjH788r/iFKdYuviQzuXmdK0Rhxf4ErQsMRf/54O+oD2FLpTH+7s w==; X-IronPort-AV: E=McAfee;i="6200,9189,10252"; a="248907359" X-IronPort-AV: E=Sophos;i="5.88,355,1635231600"; d="scan'208";a="248907359" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Feb 2022 23:41:58 -0800 X-IronPort-AV: E=Sophos;i="5.88,355,1635231600"; d="scan'208";a="540984736" Received: from hyperv-sh4.sh.intel.com ([10.239.48.22]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Feb 2022 23:41:54 -0800 From: Chao Gao To: kvm@vger.kernel.org, seanjc@google.com, pbonzini@redhat.com, kevin.tian@intel.com, tglx@linutronix.de Cc: Chao Gao , John Garry , Will Deacon , Qi Liu , Thomas Richter , Shaokun Zhang , Hector Martin , Huang Ying , linux-kernel@vger.kernel.org Subject: [PATCH v3 4/5] KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section Date: Wed, 9 Feb 2022 15:41:05 +0800 Message-Id: <20220209074109.453116-5-chao.gao@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220209074109.453116-1-chao.gao@intel.com> References: <20220209074109.453116-1-chao.gao@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 Signed-off-by: Chao Gao Signed-off-by: Marc Zyngier --- 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 773c83730906..14d354c8ce35 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -182,7 +182,6 @@ 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, @@ -200,6 +199,7 @@ enum cpuhp_state { /* Online section invoked on the hotplugged CPU from the hotplug thread */ CPUHP_AP_ONLINE_IDLE, + CPUHP_AP_KVM_ONLINE, CPUHP_AP_SCHED_WAIT_EMPTY, CPUHP_AP_SMPBOOT_THREADS, CPUHP_AP_X86_VDSO_VMA_ONLINE, diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 23481fd746aa..f60724736cb1 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4853,13 +4853,27 @@ static void hardware_enable_nolock(void *caller_name) } } -static int kvm_starting_cpu(unsigned int cpu) +static int kvm_online_cpu(unsigned int cpu) { + int ret = 0; + raw_spin_lock(&kvm_count_lock); - if (kvm_usage_count) + /* + * Abort the CPU online process if hardware virtualization cannot + * be enabled. Otherwise running VMs would encounter unrecoverable + * errors when scheduled to this CPU. + */ + if (kvm_usage_count) { + WARN_ON_ONCE(atomic_read(&hardware_enable_failed)); + hardware_enable_nolock((void *)__func__); + if (atomic_read(&hardware_enable_failed)) { + atomic_set(&hardware_enable_failed, 0); + ret = -EIO; + } + } raw_spin_unlock(&kvm_count_lock); - return 0; + return ret; } static void hardware_disable_nolock(void *junk) @@ -4872,7 +4886,7 @@ static void hardware_disable_nolock(void *junk) kvm_arch_hardware_disable(); } -static int kvm_dying_cpu(unsigned int cpu) +static int kvm_offline_cpu(unsigned int cpu) { raw_spin_lock(&kvm_count_lock); if (kvm_usage_count) @@ -5641,8 +5655,8 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, goto out_free_2; } - r = cpuhp_setup_state_nocalls(CPUHP_AP_KVM_STARTING, "kvm/cpu:starting", - kvm_starting_cpu, kvm_dying_cpu); + r = cpuhp_setup_state_nocalls(CPUHP_AP_KVM_ONLINE, "kvm/cpu:online", + kvm_online_cpu, kvm_offline_cpu); if (r) goto out_free_2; register_reboot_notifier(&kvm_reboot_notifier); @@ -5705,7 +5719,7 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kmem_cache_destroy(kvm_vcpu_cache); out_free_3: unregister_reboot_notifier(&kvm_reboot_notifier); - cpuhp_remove_state_nocalls(CPUHP_AP_KVM_STARTING); + cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE); out_free_2: kvm_arch_hardware_unsetup(); out_free_1: @@ -5731,7 +5745,7 @@ void kvm_exit(void) kvm_async_pf_deinit(); unregister_syscore_ops(&kvm_syscore_ops); unregister_reboot_notifier(&kvm_reboot_notifier); - cpuhp_remove_state_nocalls(CPUHP_AP_KVM_STARTING); + cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE); on_each_cpu(hardware_disable_nolock, NULL, 1); kvm_arch_hardware_unsetup(); kvm_arch_exit();