From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (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 64A3638D3E4 for ; Fri, 15 May 2026 19:20:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778872852; cv=none; b=Eh1YHBtMmAi8pjEypzsXLH7sem8KIbRerslTqb1YDv40Icr9IA9Zkl18dq5+oViXyv4J+TP1nXZKRJuPbaQV/Pzzp4ufq8T2GKbnpCZ2zN4jPgizIFudRctlWxe/9kinrHZss9VeSu1g/PILZRT8wC+88JYgyuRflOlrmt2l84Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778872852; c=relaxed/simple; bh=VGy+qLRWGOmAxsBGFeiFDyGswDSrJi4JQ5o9B+Fv8MU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=NY4E4GjTLrdV1vM1fNhiv576kD1rBVl33BO6f1pgkc9kTJ0vfRcDPHOLh4ePPsvLVC9a5ztYJBI0Oj/tzshZdtc8VZRxhAM/KqTdlwb5tVZSSUEJsKhJ/kQWyqqQtfotnMqgJrw+HTsA7rBQrzZ3OlfdTT+0tHxvr+OHcNw6aTg= 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=prrmj8WT; arc=none smtp.client-ip=209.85.210.202 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="prrmj8WT" Received: by mail-pf1-f202.google.com with SMTP id d2e1a72fcca58-837cc5bc6deso94373b3a.3 for ; Fri, 15 May 2026 12:20:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1778872849; x=1779477649; 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=HUz/DYTZsMDp3XmDdx4uAZCV01b5NalrmHfGrDrQY4I=; b=prrmj8WTn9wcERs264A1wlzPWbtFdwCl5pyjd6y01RajvT8AlMIT8q8WILxTU6J9IH 4sKAJvny9EphoRZCynwCKKw/MYXVT+I/q1vHyZP68aUeMxANwffIEmQoW55fNUNIcxPi 71onQ2s+N4eyksOwhm3fodes9feZh9mjl9zHAmyK1RG6mE7KlH+5pTdK1ieJ4wHR2bk8 Ha/pisoXjewzK24ihrUf8bwjKk5RecSxOo9CcNjgUoDngDgsvNae2a4sXvr8P3/cTGkR Ep2eig8wzoENrii1jXF4yzszOAz42D4lmxHQaaIVyz0x79uQ+/h06xFH1hJHqj4ZJG7J WBug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778872849; x=1779477649; 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=HUz/DYTZsMDp3XmDdx4uAZCV01b5NalrmHfGrDrQY4I=; b=HF/Oo/yGFKzwvyMNY4Drv4YNXyEm672K9V0f7rHCUybnxtlj3+fkZftBTtpwo+TJPO XUhMf4dM9/yL+VEEl8S6icn2A1ZHGQ6r5rawYdRfR6fFCW6XVZF1S4246neGpmFuthH/ q4fpjmbuvcBrMaulkdFHC0Lvw7DZKO/i1QxNK0YBAKNkDAqh6xb4Q5MioZ7VmR8bsmXp Y5YlMEHEgKJg1NoFzL1jWaDh7FBFDvwTOyOFtfBHq29cJ0XolGshYlQAWUnCcW+pndrA 6wb7sdCP+imiG9io3bGGpT420UiGQljTUmltdZTKHwqvNWLG1bzkAsUuNUrIBzh06g8c HWvg== X-Forwarded-Encrypted: i=1; AFNElJ9pXkzYQ/9CV+oOCeofJFmGF2EBqkuD+BvKByS+i6Q5TqsHtGuqwtm1fppW4l15xAQUgTptOLGlzPo8M1wO3A==@lists.linux.dev X-Gm-Message-State: AOJu0YzGeDuGc4ZZOvxKW0jnwGuOmb6Vg8IlQ4zRd2bp4BJk9kLRZHoy c6ngDOqY9UBbx48m5+ZP0YQBKiKGYtw7a8c7xQsQlmZC7iPyis6TPGWQSzIndvvtUH0LKSzLd1A sx4i6RQ== X-Received: from pfmm20.prod.google.com ([2002:a05:6a00:2494:b0:835:43a4:4aaa]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:6ca2:b0:83d:b11f:7979 with SMTP id d2e1a72fcca58-83f33c60deemr6247193b3a.29.1778872849160; Fri, 15 May 2026 12:20:49 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 15 May 2026 12:19:18 -0700 In-Reply-To: <20260515191942.1892718-1-seanjc@google.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260515191942.1892718-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.563.g4f69b47b94-goog Message-ID: <20260515191942.1892718-18-seanjc@google.com> Subject: [PATCH v3 17/41] x86/tsc: WARN if TSC sched_clock save/restore used with PV sched_clock From: Sean Christopherson To: Kiryl Shutsemau , Paolo Bonzini , Sean Christopherson , "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: Rick Edgecombe , Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , 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 , Thomas Gleixner , David Woodhouse Content-Type: text/plain; charset="UTF-8" Now that all PV clocksources override the sched_clock save/restore hooks when overriding sched_clock, WARN if the "default" TSC hooks are invoked when using a PV sched_clock, e.g. to guard against regressions. Signed-off-by: Sean Christopherson --- arch/x86/kernel/tsc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 567d30b30a5a..b14c4ada89a3 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -984,9 +984,17 @@ EXPORT_SYMBOL_GPL(recalibrate_cpu_khz); static unsigned long long cyc2ns_suspend; +static __always_inline bool tsc_is_save_restore_needed(void) +{ + if (WARN_ON_ONCE(!using_native_sched_clock())) + return false; + + return static_branch_likely(&__use_tsc) || sched_clock_stable(); +} + void tsc_save_sched_clock_state(void) { - if (!static_branch_likely(&__use_tsc) && !sched_clock_stable()) + if (!tsc_is_save_restore_needed()) return; cyc2ns_suspend = sched_clock(); @@ -1006,7 +1014,7 @@ void tsc_restore_sched_clock_state(void) unsigned long flags; int cpu; - if (!static_branch_likely(&__use_tsc) && !sched_clock_stable()) + if (!tsc_is_save_restore_needed()) return; local_irq_save(flags); -- 2.54.0.563.g4f69b47b94-goog