From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) (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 3E2E53E1721 for ; Fri, 15 May 2026 19:20:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778872851; cv=none; b=gX46USJIPm1h7OuRsCNYX6Zzs7EV8OYnXSk/A7As4sb3XrtkgzLmV9u8eEkYrNfzp7yoUUUywly1Kf3XlyGiOB3xGrISb67UOxTyqVEPgyA5lzvHn+KJV2SEMRv4yW+DlCzacQNfIW5rXx9+ogcIlPkxF7njb0+B2DP13PP4HrM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778872851; c=relaxed/simple; bh=VGy+qLRWGOmAxsBGFeiFDyGswDSrJi4JQ5o9B+Fv8MU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=q5d+yKPQ0YT/t73ZZQ4BnRR3j6CW3PJrFxY0MMJYSfqCCVTP3FIWAwILIUNd5EspPouO985g66NySsRYX2WxX6tJzkO1aMAugv3WAPitSR65+z+ZcmnHgbrgq9Fysr6rw2qSz/4PCSFDWMI++nc6OheDktcEoM913dXilAYlANM= 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=X/N4q977; arc=none smtp.client-ip=209.85.210.201 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="X/N4q977" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-837cc5bc6deso94372b3a.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=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=HUz/DYTZsMDp3XmDdx4uAZCV01b5NalrmHfGrDrQY4I=; b=X/N4q977l45ITMvll/o0+19guoFFUzxLB98uebW0VHaX5g1ESYoQcY1gm4J7J68uAK eNANpepCp+hfuEVQFDB0cK+WZnMxyypsOWfHpikWrR/1W1liCKDNCCt3VvI94ry6sL+N ZMmVfe3GB71WPKZZWlTfkYQoUhqgnt2CYGK7OSuZu4aYLbVgckPVRutwiZ1vLajkusK4 abciy5J/7KTbhz0j1cnW+Q8p9ZTK2bqSwBNx+GzIrAK/owHrOROSMOFC/YEgF49E27+k luy9LifUxLCS6088HLQLTSzDs/A6J97LYu9WSpHihGiARsHfhmkLtWCOpwDw8oS8YnVP FM4Q== 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=sed7MlEpChHJRkQyiPCqwNGv9+bf1cmyFdr3AW81OZVulynH9XBHaRRaex33MfI/SI UI0wH3YdRb6vGVvESVttnsDNRKE6T8QryJufXE7ZpzWTI4/xByC37zPmphggsA7ZUW/G 0jjssXD/pLgyMSz8dvn+ndtxdZAy1CBGLw9gbHpeD18+LRnQfDXEQp0faHeFHJdmnQWP gmCQFmh38USPpDOAM/lGjtzGszzEhsHiW8fG8+uo9E+J2p0+uIL03T2F/Lzh52kHIb3S 28knjvS1jfApN85rczzOeZEMA5lLUUqss4jSHHgJamJMQPvZSNmJUsf3mO5zOHgRrv+3 PgLw== X-Forwarded-Encrypted: i=1; AFNElJ9AO8d9mw0YSRR2FFQgIkC84h1/BD8KjzU6jUlaEkxEjrcbXG3SjXycLcbS35rYgGg89287HJuapYqWNpY=@vger.kernel.org X-Gm-Message-State: AOJu0YwUAnecC26hbvsikE9D86yRPIVKgwa+1DPK2Y1pp33DLGXJUhdt sKvhUEJhh6XbejY8ZM5jlAF5hP6t8XuvX0anwG2wEcqsMcE7kYxay6ft6LGd+Hv3aIUXxo48lAe I9Et6Tw== 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: linux-kernel@vger.kernel.org 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