From patchwork Thu Feb 27 02:18:28 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 13993557 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 8FF5F1E5200 for ; Thu, 27 Feb 2025 02:19:24 +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=1740622766; cv=none; b=IJwZFxIxMURqA3EdEeWUmDAO2itlNLn6fOwcFq0FuqXO2CN/DY43HZC6wcoKDTWey3N0LWuUtMwSOk0iOy7JvzQj9OCVjkpMLUE1M968qHKjqBmwQIIaCTvUOPHU5gaxWCf2m84+PPZewvAlNsPeN51AdFSzVmSbBFJAdda1H98= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740622766; c=relaxed/simple; bh=pVoicbIwuy1mW6yiJjZE1VBeAcXEO4G9pyLaBIqAzFg=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=LZHSP+qSOwMRvGqc+Ra5JHQomzxad1IazLB4clOXPj/pZRgdge6a7T1KyBONVGFfM98V1xTjfXYBs0pR/ahkIrNvbuKRtWxlOKXKa/GvE9JaLMv1xQplGM+a6K280+uA3Qwnvo+BBSqIpDvjtNPVwfLYNk81A4XvfP6UxrlBzxM= 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=aSZdGUdG; 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="aSZdGUdG" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-220d8599659so8015615ad.0 for ; Wed, 26 Feb 2025 18:19:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1740622764; x=1741227564; darn=vger.kernel.org; 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=pWgviwpmhKNHN5XYXpAWmYugB+1r1OlVvpsKGRVLlVs=; b=aSZdGUdG9PggLvyeJRebhiWHxzWA9PuNRcV4J86i7bawIEtnsWu5J4cddSAVay9h50 jbFCEnj+9zA2ksgeMg/JhZ2auP6arQvICtagr2OHWNBcmkFXDynRLlr8sR3S3MT0Vfhh TcNZjgMS8pk4TE71O66ZLt3iTwFaM9l2eWTtf0YLPo6VGe8xz1ROkOzLR1hV9aAMGQrI 5OuMlBDCcDS7yFtYHkE+GF9dao7CVhb0iYNqa6sQuPIjtU0PmXC004Ssvoo8+HjP4hv4 E5Q82fNKSyIaprKL4z1MRPldJC+NW0tYdlv+tDYphYLLf1hoKp7sHKo6U1Sb4Vm5bDeo yBCw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740622764; x=1741227564; 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=pWgviwpmhKNHN5XYXpAWmYugB+1r1OlVvpsKGRVLlVs=; b=E3nM1hrPLwawbrYuCO+st2WCgyNK1KauZ82TRVqEgquniCSmqBxoFa/YuLSP2hlK1+ sJ7rlYQXKvd8bIyW99SJRXnkdU3pLTJ5USvyRmlThRy/+95gBtkJ88eyefXuektSP3Zc lqPkRBwFwitqrek0WfCyECWOcVMOqeS52zW+bSI9MpU+XjfGnwN7NnPFS29Wq3iynI5W rw79FdfMVN3gYCBxMaSwA71fVJIi3Cd2HL9zy565BngIUBTm57cKgM9I1TOFSmmX2gWf muO7eckAzF0mTosa0uwakSOpv9HFw6jA5e6AZwtN0+0+NGSDmouv31Its2c2zyLqXMz5 4Svw== X-Forwarded-Encrypted: i=1; AJvYcCVrUUpdDTsfFLtY1glHD9G62AotyvfCK5N07scJxx4jL451QkBEg16T5QrkeIGSuD3NYgM=@vger.kernel.org X-Gm-Message-State: AOJu0Yz1i2d2wo/qYtuZdnlSy7kul1vfmzU19HtX3GEMCwER3SIoD7fi 1VYvYJwqCfWcWMrI8yQgIwRwO7bpYvxHrZJCRXkzLLzIZvaV+O/iQI15BKSIVBA5YE7lrRWWRWR SyA== X-Google-Smtp-Source: AGHT+IGQazOm0zxmui59w45JCda9qTDjxRSvZp9ylt3tyNT0rDqeQIE65vrdsSLJOsVjaLh1NupfPRbt/dc= X-Received: from plblo7.prod.google.com ([2002:a17:903:4347:b0:21f:429a:36ae]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:ecca:b0:220:f06b:318 with SMTP id d9443c01a7336-22320080b32mr91766195ad.14.1740622763961; Wed, 26 Feb 2025 18:19:23 -0800 (PST) Reply-To: Sean Christopherson Date: Wed, 26 Feb 2025 18:18:28 -0800 In-Reply-To: <20250227021855.3257188-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250227021855.3257188-1-seanjc@google.com> X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250227021855.3257188-13-seanjc@google.com> Subject: [PATCH v2 12/38] x86/kvm: Don't disable kvmclock on BSP in syscore_suspend() From: Sean Christopherson To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "Kirill A. Shutemov" , Paolo Bonzini , Sean Christopherson , Juergen Gross , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Ajay Kaher , Jan Kiszka , Andy Lutomirski , Peter Zijlstra , Daniel Lezcano , John Stultz Cc: linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, virtualization@lists.linux.dev, linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org, Tom Lendacky , Nikunj A Dadhania Don't disable kvmclock on the BSP during syscore_suspend(), as the BSP's clock is NOT restored during syscore_resume(), but is instead restored earlier via the sched_clock restore callback. If suspend is aborted, e.g. due to a late wakeup, the BSP will run without its clock enabled, which "works" only because KVM-the-hypervisor is kind enough to not clobber the shared memory when the clock is disabled. But over time, the BSP's view of time will drift from APs. Plumb in an "action" to KVM-as-a-guest and kvmclock code in preparation for additional cleanups to kvmclock's suspend/resume logic. Fixes: c02027b5742b ("x86/kvm: Disable kvmclock on all CPUs on shutdown") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- arch/x86/include/asm/kvm_para.h | 8 +++++++- arch/x86/kernel/kvm.c | 15 ++++++++------- arch/x86/kernel/kvmclock.c | 31 +++++++++++++++++++++++++------ 3 files changed, 40 insertions(+), 14 deletions(-) diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h index 57bc74e112f2..8708598f5b8e 100644 --- a/arch/x86/include/asm/kvm_para.h +++ b/arch/x86/include/asm/kvm_para.h @@ -118,8 +118,14 @@ 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_AP_OFFLINE, + KVM_GUEST_SHUTDOWN, +}; + void kvmclock_init(void); -void kvmclock_disable(void); +void kvmclock_cpu_action(enum kvm_guest_cpu_action action); bool kvm_para_available(void); unsigned int kvm_arch_para_features(void); unsigned int kvm_arch_para_hints(void); diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 7a422a6c5983..866b061ee0d9 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -447,7 +447,7 @@ static void __init sev_map_percpu_data(void) } } -static void kvm_guest_cpu_offline(bool shutdown) +static void kvm_guest_cpu_offline(enum kvm_guest_cpu_action action) { kvm_disable_steal_time(); if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) @@ -455,9 +455,10 @@ static void kvm_guest_cpu_offline(bool shutdown) if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0); kvm_pv_disable_apf(); - if (!shutdown) + if (action != KVM_GUEST_SHUTDOWN) apf_task_wake_all(); - kvmclock_disable(); + + kvmclock_cpu_action(action); } static int kvm_cpu_online(unsigned int cpu) @@ -713,7 +714,7 @@ static int kvm_cpu_down_prepare(unsigned int cpu) unsigned long flags; local_irq_save(flags); - kvm_guest_cpu_offline(false); + kvm_guest_cpu_offline(KVM_GUEST_AP_OFFLINE); local_irq_restore(flags); return 0; } @@ -724,7 +725,7 @@ static int kvm_suspend(void) { u64 val = 0; - kvm_guest_cpu_offline(false); + kvm_guest_cpu_offline(KVM_GUEST_BSP_SUSPEND); #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) @@ -751,7 +752,7 @@ static struct syscore_ops kvm_syscore_ops = { static void kvm_pv_guest_cpu_reboot(void *unused) { - kvm_guest_cpu_offline(true); + kvm_guest_cpu_offline(KVM_GUEST_SHUTDOWN); } static int kvm_pv_reboot_notify(struct notifier_block *nb, @@ -775,7 +776,7 @@ static struct notifier_block kvm_pv_reboot_nb = { #ifdef CONFIG_CRASH_DUMP static void kvm_crash_shutdown(struct pt_regs *regs) { - kvm_guest_cpu_offline(true); + kvm_guest_cpu_offline(KVM_GUEST_SHUTDOWN); native_machine_crash_shutdown(regs); } #endif diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 80d1a06609c8..223e5297f5ee 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -177,8 +177,22 @@ static void kvm_register_clock(char *txt) pr_debug("kvm-clock: cpu %d, msr %llx, %s", smp_processor_id(), pa, txt); } +static void kvmclock_disable(void) +{ + if (msr_kvm_system_time) + native_write_msr(msr_kvm_system_time, 0, 0); +} + static void kvm_save_sched_clock_state(void) { + /* + * Stop host writes to kvmclock immediately prior to suspend/hibernate. + * If the system is hibernating, then kvmclock will likely reside at a + * different physical address when the system awakens, and host writes + * to the old address prior to reconfiguring kvmclock would clobber + * random memory. + */ + kvmclock_disable(); } static void kvm_restore_sched_clock_state(void) @@ -186,6 +200,17 @@ static void kvm_restore_sched_clock_state(void) kvm_register_clock("primary cpu clock, resume"); } +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) + kvmclock_disable(); +} + #ifdef CONFIG_SMP static void kvm_setup_secondary_clock(void) { @@ -193,12 +218,6 @@ static void kvm_setup_secondary_clock(void) } #endif -void kvmclock_disable(void) -{ - if (msr_kvm_system_time) - native_write_msr(msr_kvm_system_time, 0, 0); -} - static void __init kvmclock_init_mem(void) { unsigned long ncpus;