From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 0418A42D717 for ; Wed, 1 Jul 2026 19:33:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934411; cv=none; b=JNayviE0itymXYZqkp1m2lmNprCh/Ho/Pk4LSesrdcyM+Dzu04lUKF9ZB+TPZ3nADrqYPEaK5zcx9Xg0z4CzakuHYoSsXryBUhXln0EGNTjrUGjfrFxLmOPGzl8bYBegAAty0Mnn5s4Gs3HCiulic25/A0GeS6f1z57Lwi2u8YY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934411; c=relaxed/simple; bh=1PQjxlx5nubnpTfQaTN8BFLRTtJFTrF7SV6DilzQr90=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=mWp2rTRPtTWDUz2Ryq45HT7v7iWApwQIqOG63KDZ9NtKv43P11LXpJwl/zaUdVqBFNtbECbUogCvzqY9je6nnF7UU42bTZaVAw5Qg5Z2xPpbm6YULZRSJChLsXYoPwdsuLsig0MPzpaGCwausVVhAz+CYqLM3jzyN/K3vVrkzjY= 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=mF2aRt5l; arc=none smtp.client-ip=209.85.214.201 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="mF2aRt5l" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2ca1f16e391so11759115ad.2 for ; Wed, 01 Jul 2026 12:33:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1782934406; x=1783539206; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=TVQraC4E63kxSjnR08hIOoNSz/X8YqL1FfZb6Oo6qbM=; b=mF2aRt5luufORknBn/Ssk38uISGjIwAVdyXhUMIYxFeJgqIfvPn5ADFfYSAP0db5Gk Xd0YA97G01Rhow5X89oRwBUnjaC8QZ5O+vFfYDRTyZQ3EfBnfL3j+qm8QmohUZNH+tot pg4GNLoJDtBUkBIMI6B7JUtBkcKiecgHmdt8wGfszL14PgKP4U1zK8USFclC9jOxF/Id u/bU/UNpp9ByWRc+CEOS8ejgK6g3iwpESHZkc61+8N8j5wseD8rLiQU8SG2g+cRF35iR xxXiWtaxh9S1kDAF0x3ULS6tMgkzANR4QnxWbKed/sOx9Zi9WL1QLS4hK26XvYGQAPY0 JSHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782934406; x=1783539206; h=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; bh=TVQraC4E63kxSjnR08hIOoNSz/X8YqL1FfZb6Oo6qbM=; b=kqW7juyMcwnQ/Ve4n059N6MI6KdO9e1pgnV7lMb4wtd7pTXKA2MjSp4WjrEtVABfar DtPBE26VrA5nkGL7tIHOLZLcM2xFE8YTF2YXLrASs8VU4f4CcthhYZtvm/nKCmlacuKP aLYjzGejDY3uhUXCR4WTF4lGDqQtwxujPDq+x/hyTBDSzRWX4vBu5r35TwaYiLEITc9/ rOULxNgZuA1Anpy/0AvQ0edJ5A7xgCFotYkB8lUgDlL1Qys9orUOZFh4zVBnhsFatfoi bQcdWQ8GxO6oUVzllQtHdTKzAD6SFvKUsHfADapEIm1bLB/Jod1y2UkL4vQUZZRsTkIB mEvw== X-Forwarded-Encrypted: i=1; AHgh+RqUWgQEmf+I77I9S+llzOMpJxbgwEaLia0fyEtyJEyVQvILU8qOT7OHAh9gB12kcIoqNO9ZvlHzlIF7@lists.linux.dev X-Gm-Message-State: AOJu0Yy8LJ2hmz4eGCeP+mGx/o1R9rwIe51xAIDJebV4qug42C1NPemQ okD9e5v5EAuydx64UX78xupQFG/WDYfhWxDul8FjA4E57NA0DaZ8yxF+N4Vk0uQArCr4JRtLx1b rkV0n/w== X-Received: from plkg7.prod.google.com ([2002:a17:903:19c7:b0:2c6:a4ed:efee]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:c94c:b0:2c9:c97e:71cf with SMTP id d9443c01a7336-2ca7e683909mr35659695ad.6.1782934405912; Wed, 01 Jul 2026 12:33:25 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 1 Jul 2026 12:32:10 -0700 In-Reply-To: <20260701193212.749551-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260701193212.749551-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.rc0.799.gd6f94ed593-goog Message-ID: <20260701193212.749551-50-seanjc@google.com> Subject: [PATCH v5 49/51] x86/kvmclock: Plumb in AP-online and BSP-resume to kvmlock, for documentation From: Sean Christopherson To: Jonathan Corbet , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kiryl Shutsemau , Rick Edgecombe , Sean Christopherson , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Ajay Kaher , Alexey Makhalov , Jan Kiszka , Andy Lutomirski , Peter Zijlstra , Juergen Gross , Daniel Lezcano , John Stultz Cc: Shuah Khan , "H. Peter Anvin" , Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , linux-doc@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, xen-devel@lists.xenproject.org, Tom Lendacky , Nikunj A Dadhania , David Woodhouse , David Woodhouse , Michael Kelley , 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 604b52f233aa..f9a6346077b0 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) @@ -750,7 +756,7 @@ 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.rc0.799.gd6f94ed593-goog