From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f197.google.com (mail-pl1-f197.google.com [209.85.214.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DEFB44ACCE3 for ; Thu, 6 Aug 2026 23:37:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.197 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786059451; cv=none; b=FowFdQ++9F7h82S3wM9pnqo+o9RR82nUB/zZq4LJh/IwCTN3PmB14WkS1rNqDkIfvPOuXMhma3OcC0SXT46HTY/Liid3vytVqxTxZM2woHzDON1tc0NYHXrHnFIJTWtGDX7VYZWIoSkZRXGU63WoTstVmkdlw92cyzXtO5QhvWY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786059451; c=relaxed/simple; bh=DotEodtP+5nx+qQ2PED5Az3WVrkKwKmbTzb/y5Tt2sE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=UNz0rvwjjh9ZO5hRI0+7i35JDAXc2gQGmcYubJHp/OFY8Sz0ODcz7mJ1w9ifDxhWGalm8ROqTZD+ncgB5stSwKo7C7Rp/0kp6A8wUfoMujWG7NOAnn66um4IcJq57O2snieImxgn6JMg1XwgQoz4uZxXJTOWy65RWE8oAKsZnG0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=CLpLfWHr; arc=none smtp.client-ip=209.85.214.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="CLpLfWHr" Received: by mail-pl1-f197.google.com with SMTP id d9443c01a7336-2cfa55c9430so27862195ad.0 for ; Thu, 06 Aug 2026 16:37:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1786059445; x=1786664245; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:reply-to:from:to:cc:subject:date:message-id :reply-to:content-type; bh=/TxUyuE9/koLQyW6zcM5dMaQ+pcBou93eYQoJAAWN+E=; b=CLpLfWHr+iPxI9WBbdFWWWvKTRL2bJeWYuZfzK0uXV/2EYzCuUezUStwDFpOg6yc5N WrI4aUOptdE7Z08WnoTh6IM9q6r8ffiyKLRt0yyDE/HnTzDozpU9UHL7Vi3FZe1ugKLK dLYAQuVPiVMGeGqFdlAcbZ51zuVmgC7SbqVvLGJFlMDHokLojUnMRe0nuYX5Hh/VWH85 0npF2TdFqdA3RuWaLICOv8vabJKCOoefAbCo/gsmw9bYxUGZBt22A8osgxAr4CgtTke3 OpNhmZe9Tf3v1x+dU3gmcKftdIFhlrOKxUWPXAaS9+d0eMgMA+cUBywRpkP0/TPw3nPI 2IRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786059445; x=1786664245; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:reply-to:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to:content-type; bh=/TxUyuE9/koLQyW6zcM5dMaQ+pcBou93eYQoJAAWN+E=; b=DLbMlH3EJmA05WszctPNHJTLLeDnZvrPpCMSj6OxEq0HT2ncZ0X0UkDMi9DKDgvzZY ePeZ3vlmn4JM7xFMEk6J2dKzK6h6nk3JbwA7vB/SK7WejVhQNYo1VVEX3VYQAZYNy9js bG9Faq7jFgFWoYQ1Q+r0yzLD7YmZN1kOKI0MPfdLFoWPbDRSpRbiF5nE11HNglFKIfNJ r2krrp9nrcHWqiWhgpGhN3hP+P51UG//DeVPQoxhb++97IXVYJo/7MuLBNlr3wMBn3Lx tHJDM75K8Y+vNvS0IxB4/xCfmOP5lmPJikxm8z1Gi3n7kap3lpTl4AE8ybzueI96iLm0 D35g== X-Forwarded-Encrypted: i=1; AHgh+RqNSx9+shnVmz1iCYoiGH8rp8LkYzQMuNx2FPHAwbmD69ZjkRnrhof0j54h6nFQG/bqyjI=@vger.kernel.org X-Gm-Message-State: AOJu0Yw76RPFSQizn8EIMgQAEQOEUnsgx1maP1MdN1Ciorn+DQUpIMEW k7+tv1cGmuydr9U2Nft5KI9PEodSliDWxqWRBjBiyl/MKTJ8DBc7wp+PkJuyU9LphbG7fFyt0xF 5tfO9dA== X-Received: from plgi9.prod.google.com ([2002:a17:902:cf09:b0:2c7:e06e:86f6]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:c402:b0:2c9:c952:6e9 with SMTP id d9443c01a7336-2d0ca7b024fmr202039245ad.2.1786059444816; Thu, 06 Aug 2026 16:37:24 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 6 Aug 2026 16:36:06 -0700 In-Reply-To: <20260806233609.212337-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260806233609.212337-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.679.g6767b8d81c-goog Message-ID: <20260806233609.212337-50-seanjc@google.com> Subject: [PATCH v6 49/51] x86/kvmclock: Plumb in AP-online and BSP-resume to kvmlock, for documentation From: Sean Christopherson To: Kiryl Shutsemau , Rick Edgecombe , Sean Christopherson , Paolo Bonzini , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Ajay Kaher , Alexey Makhalov , Jan Kiszka , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Juergen Gross , Daniel Lezcano , Thomas Gleixner , John Stultz Cc: Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , Miroslav Lichvar , x86@kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, Michael Kelley , Tom Lendacky , Nikunj A Dadhania , David Woodhouse , David Woodhouse , Thomas Gleixner Content-Type: text/plain; charset="UTF-8" Invoke kvmclock_cpu_action() with AP_ONLINE and BSP_RESUME, even though kvmclock doesn't need to do anything in either case, so that the asymmetry of kvmclock is a detail buried in kvmclock, and to explicitly document that doing nothing during those phases is intentional and correct. For all intents and purposes, no functional change intended. Reviewed-by: David Woodhouse Signed-off-by: Sean Christopherson --- arch/x86/include/asm/kvm_para.h | 2 ++ arch/x86/kernel/kvm.c | 22 +++++++++++++------- arch/x86/kernel/kvmclock.c | 37 ++++++++++++++++++++++++++------- 3 files changed, 45 insertions(+), 16 deletions(-) diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h index 08686ff19caa..763ed017738a 100644 --- a/arch/x86/include/asm/kvm_para.h +++ b/arch/x86/include/asm/kvm_para.h @@ -120,6 +120,8 @@ static inline long kvm_sev_hypercall3(unsigned int nr, unsigned long p1, #ifdef CONFIG_KVM_GUEST enum kvm_guest_cpu_action { KVM_GUEST_BSP_SUSPEND, + KVM_GUEST_BSP_RESUME, + KVM_GUEST_AP_ONLINE, KVM_GUEST_AP_OFFLINE, KVM_GUEST_SHUTDOWN, }; diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 9c0b2fc98cc9..b954238b09fc 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -474,18 +474,24 @@ static void kvm_guest_cpu_offline(enum kvm_guest_cpu_action action) kvmclock_cpu_action(action); } +static void __kvm_cpu_online(unsigned int cpu, enum kvm_guest_cpu_action action) +{ + unsigned long flags; + + local_irq_save(flags); + kvmclock_cpu_action(action); + kvm_guest_cpu_init(); + local_irq_restore(flags); +} + +#ifdef CONFIG_SMP + static int kvm_cpu_online(unsigned int cpu) { - unsigned long flags; - - local_irq_save(flags); - kvm_guest_cpu_init(); - local_irq_restore(flags); + __kvm_cpu_online(cpu, KVM_GUEST_AP_ONLINE); return 0; } -#ifdef CONFIG_SMP - static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); static bool pv_tlb_flush_supported(void) @@ -752,7 +758,7 @@ static int kvm_suspend(void *data) static void kvm_resume(void *data) { - kvm_cpu_online(raw_smp_processor_id()); + __kvm_cpu_online(raw_smp_processor_id(), KVM_GUEST_BSP_RESUME); #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll) diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index bc98ebb8587d..842f38c5f6ca 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -150,7 +150,7 @@ static void kvm_save_sched_clock_state(void) #ifdef CONFIG_SMP static void kvm_setup_secondary_clock(void) { - kvm_register_clock("secondary cpu clock"); + kvm_register_clock("secondary cpu, startup"); } #endif @@ -174,13 +174,34 @@ static void kvmclock_resume(struct clocksource *cs) void kvmclock_cpu_action(enum kvm_guest_cpu_action action) { - /* - * Don't disable kvmclock on the BSP during suspend. If kvmclock is - * being used for sched_clock, then it needs to be kept alive until the - * last minute, and restored as quickly as possible after resume. - */ - if (action != KVM_GUEST_BSP_SUSPEND) + switch (action) { + /* + * The BSP's clock is managed via clocksource suspend/resume, + * to ensure it's enabled/disabled when timekeeping needs it + * to be, e.g. before reading wallclock (which uses kvmclock). + */ + case KVM_GUEST_BSP_SUSPEND: + case KVM_GUEST_BSP_RESUME: + break; + case KVM_GUEST_AP_ONLINE: + /* + * Secondary CPUs use a dedicated hook to enable kvmclock early + * during bringup, there's nothing to be done during CPU online + * (which runs at CPUHP_AP_ONLINE_DYN). When kvmclock is being + * used as sched_clock, kvmclock must be enabled *very* early, + * and even when kvmclock is "only" being used for the main + * clocksource, it still needs to be enabled long before the + * dynamic CPUHP calls are made. + */ + break; + case KVM_GUEST_AP_OFFLINE: + case KVM_GUEST_SHUTDOWN: kvmclock_disable(); + break; + default: + WARN_ON_ONCE(1); + break; + } } /* @@ -382,7 +403,7 @@ void __init kvmclock_init(bool prefer_tsc) msr_kvm_system_time, msr_kvm_wall_clock); this_cpu_write(hv_clock_per_cpu, &hv_clock_boot[0]); - kvm_register_clock("primary cpu clock"); + kvm_register_clock("primary cpu, online"); pvclock_set_pvti_cpu0_va(hv_clock_boot); if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) { -- 2.55.0.679.g6767b8d81c-goog