From nobody Mon Feb 9 12:25:00 2026 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 3489C22D4E3 for ; Thu, 27 Feb 2025 02:19:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740622785; cv=none; b=c7fnKYR5Pfk9VzIRi17xApUBJ00XTaSHatSm6styX2PZFt1PVfAL29A003pcmTR3Jar/W1xg16QXdcWiZZbF63E/YasTTTCIpPPoJynOGfDxUO0Uazqhtniuj9chfVf3y1pn16FPzHMdknW6jNpigpL2XdaVHRTlLTACJU+2fbQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740622785; c=relaxed/simple; bh=c8XZYUiY0W1+X8puZluFjrjS+RyDGH52gngoWNRH5Ko=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=rl8EhRDyUD6ibQ3lZtS0WL/HOo/UogpIQxCDbkJAESDLmssHWLx+cHGvLPuGvXk3+1TLAkMcRSagr7QxaSSUkTbUDFqtRCaqLANoKBbRsvf6SorYUeaURq8cS+JtG7bGfceI0GvYb8/zmRTf77MdXCZqqLgAILNyt0zcxDhvdOk= 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=iNc5mDBO; arc=none smtp.client-ip=209.85.216.74 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="iNc5mDBO" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2fc518f0564so1095864a91.2 for ; Wed, 26 Feb 2025 18:19:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1740622783; x=1741227583; 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=Za0nk5QeJovZveNmDgTJSzh3R0hb/7p0/gaKYZ4C/Vs=; b=iNc5mDBOH6iCXAVl7fjXBB9NgQAegd+oFXUTQf6c7PPrBAeGbAM/xfNDCJqf2qRxqw bEwsnT1BcjunEHggVxC4KaaBcADtyp41QpGbbZp9/85769HwwPFdK7phSzJxBg1u/xgZ YB9QzyOrvlejcioFW7BpLj298Kkm1gJMskSZ610tAKp7DEMKb4Kf1gpCnoZUupe/JVTC M/ADlrlXbMYVcCf1AuRlKMQbSQLeifzjE/jaZFtR92da7oNnNv44+sEK7wOgaK6ldpHj Ugef1n6qwdO/HftDAw5G6R1yxYGtOVczOGODa98lJye+UP4lLyOErt3pyr9/pJQKM/M/ KlTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740622783; x=1741227583; 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=Za0nk5QeJovZveNmDgTJSzh3R0hb/7p0/gaKYZ4C/Vs=; b=pONkEfBgQ+Q9djdCP+cQFFgVACiSF5V53gSOIXSnJAPd8utVY/Skzuy4H8oRaFy5yq RwaolN8UwC220Eeg7nTCXweRXR4rmg7vl2tS8aI/vakH6VKzCPe25rLK1heucK91UfrO 6tlyN67mrMsH31bHhlp9Vk+uXItfnKMUbB5jltf4jMJh31yEl+sfGDxGS7tYAkmXJigM WNGE6wfjasR/dlP9Hn0YKEdKutnCkJkQo9aZmX2ykWWpZC0kx/k6RFbdVTCmA5iDNTzn TZ7ztXJAlf9asitR3XeitTMLIciBjOfexz7F8yGIhWTXG/etR/1AC8pBgR2IdHHP2qzr +pww== X-Gm-Message-State: AOJu0Yx0irQ1+GhOB5TvooBoUw4btAibySA1QrBjfnOWjCr45IintlMm yOk8FsqMqd7tGtnKSElRGtgX9FMDYbsB0IA3b93LPSN9Ys1yybaBNNnv2aEMlW49l8x0TfNXkaU LTA== X-Google-Smtp-Source: AGHT+IHPEy5y9WPVcI/hX8J+CDDBk9ezIawKhLRmwSNwFlW/vj5Sb4uKTsOn6iseYydXRMp+Q/+8QjZLtQQ= X-Received: from pjbsm1.prod.google.com ([2002:a17:90b:2e41:b0:2f8:4024:b59a]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90a:d2d0:b0:2ee:b6c5:1def with SMTP id 98e67ed59e1d1-2fe68ad9ef3mr15165448a91.8.1740622783395; Wed, 26 Feb 2025 18:19:43 -0800 (PST) Reply-To: Sean Christopherson Date: Wed, 26 Feb 2025 18:18:39 -0800 In-Reply-To: <20250227021855.3257188-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20250227021855.3257188-24-seanjc@google.com> Subject: [PATCH v2 23/38] x86/kvmclock: Refactor handling of PVCLOCK_TSC_STABLE_BIT during kvmclock_init() 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 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Clean up the setting of PVCLOCK_TSC_STABLE_BIT during kvmclock init to make it somewhat obvious that pvclock_read_flags() must be called *after* pvclock_set_flags(). Note, in theory, a different PV clock could have set PVCLOCK_TSC_STABLE_BIT in the supported flags, i.e. reading flags only if KVM_FEATURE_CLOCKSOURCE_STABLE_BIT is set could very, very theoretically result in a change in behavior. In practice, the kernel only supports a single PV clock. Signed-off-by: Sean Christopherson --- arch/x86/kernel/kvmclock.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 934ee4a4c6d4..0580fe1aefa0 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -304,7 +304,7 @@ static void __init kvm_sched_clock_init(bool stable) =20 void __init kvmclock_init(void) { - u8 flags; + bool stable =3D false; =20 if (!kvm_para_available() || !kvmclock) return; @@ -331,11 +331,18 @@ void __init kvmclock_init(void) kvm_register_clock("primary cpu clock"); pvclock_set_pvti_cpu0_va(hv_clock_boot); =20 - if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) + if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) { pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); =20 - flags =3D pvclock_read_flags(&hv_clock_boot[0].pvti); - kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT); + /* + * Check if the clock is stable *after* marking TSC_STABLE as a + * valid flag. + */ + stable =3D pvclock_read_flags(&hv_clock_boot[0].pvti) & + PVCLOCK_TSC_STABLE_BIT; + } + + kvm_sched_clock_init(stable); =20 tsc_register_calibration_routines(kvm_get_tsc_khz, kvm_get_tsc_khz); =20 --=20 2.48.1.711.g2feabab25a-goog