From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (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 F37FC3F4DEC for ; Fri, 29 May 2026 15:07:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780067280; cv=none; b=TIwHnBk+2ulNk3F7s7ej0o7jz2V5dkhdUGG5WrEPxZmeM2dxJdkLecsq5pGhz4iiS3IKEaWswOTJQHDB4O9vklzP1Ds+GBvUrqWgDDu55WlNyVwrmP7L4bjDF4Kf1ZTJWS3n5kPvuYko3hiUsVIScar1A6N6BEPDdSSNVKimNgM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780067280; c=relaxed/simple; bh=FpeYXKUVm9PMkFdOsJA/iB3JokpDn1J3KKT5u4Rg4HU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=PDHm3u6Vx5T+xG6DGND0e5DtsCH79HuaPjyLf5g/7HEQj786wBbZGFwluKkZcqJZA3Y2o9WhPBvY7GFGGrMxfseb0JG4zFx3KM9QK8Nwky7/igwyBQNfH+6iBR/tHvrYaPqTIhxNSTkjPNDbKYfR0qm2ZOnMutuBfvXzOHVaNq8= 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=b9JNIt1I; arc=none smtp.client-ip=209.85.215.201 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="b9JNIt1I" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-c8582b167f7so40250a12.0 for ; Fri, 29 May 2026 08:07:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780067278; x=1780672078; 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=xxACJL8GJmmB0S+liLqaHbVRa5fkFAryvwd+hR3Tj1U=; b=b9JNIt1Ic+EAvLbmi/VvDrnOyiWdpByg3+YYJAXpK7v1JnO4lZvzr9j4po50wErPWE OsS7HnnVBtX7zV9TlehJ8HL278P6jxU+QluPqt28UefFE1mwCP6IaR2cHHn1Tfcxc5dJ Bgk8L3KiXlvWc00cKuEA/X5EbAZ9rWUxWCzZ7L8ZI0aFEy+c5qLFoA9Weo0gN1cMbvSI wlsmk4urgLQIWj3cs1BfIUxNoIAWY4rOt7JKI7SCOGM5HEHTTC1MVJfMk1+vMRHykn+z XTL/mE8+zQS2mLsi9/K8KrtfkbcHrhsPuIrhf23k9obEU11bSIkdRgg/QnwZV/8kzwyx N6dQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780067278; x=1780672078; 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=xxACJL8GJmmB0S+liLqaHbVRa5fkFAryvwd+hR3Tj1U=; b=B+WKAFnAlw0pgN/VvT4kqE/rYUBpMUR5u/iuQX8rBBroOxRbQFod3e6n2QQ+7pRBi1 oQCD7j8iV++txnp0Hx3WKdIcGgNBHawk28Lx3LToag4rNgRr59XMle1Uu2zI4ReEi3tb efKrU8/IJLsA53Tp/PIKRVyxBtvbnAMNGjTrubo3BZcbMo8Dz9GueZjXBIc4KtC9U3sL /4zrjmutiu4+b6zOV0yn194ICx5CTGH9Z7K3dodb7XrC2h9VmROjELF607hkGLOOQiEB GIRKc10YVE+tWIMEOJhm0ShbpDfX9f+SQMj8jnTtfLb+t6xKvd2QjfaCQmyuGBDaHYpT OzWw== X-Forwarded-Encrypted: i=1; AFNElJ8y/Nb3QJ6khKOJ/AQfpLSDCK9E0WIKfjCJXvcX6O68n9FglNkgKcMYNjwq/QAH6arp7hqs8hyKDZM3EwPHsQ==@lists.linux.dev X-Gm-Message-State: AOJu0YzVujMimz5yMohVsTXVMt+1hyZieulqYKv4JEMpOBSmpci4jqNI RiHqvuYDjVaGET5bC4MKyrgTUBycKDwBXrpqVfvPWaV3jhlSJjoU801HJPZcLZ2G+8hPc5Mcx8q 9ksJn+A== X-Received: from pgbda10.prod.google.com ([2002:a05:6a02:238a:b0:c80:2987:4220]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:9f88:b0:3b3:1951:489b with SMTP id adf61e73a8af0-3b411e714f7mr3887670637.45.1780067278068; Fri, 29 May 2026 08:07:58 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 29 May 2026 08:07:55 -0700 In-Reply-To: <20260529144435.704127-1-seanjc@google.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260529144435.704127-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260529150755.714364-1-seanjc@google.com> Subject: [PATCH v4 32/47] x86/tsc: WARN if TSC sched_clock save/restore used with PV sched_clock From: Sean Christopherson To: Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kiryl Shutsemau , 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: "H . Peter Anvin" , Rick Edgecombe , Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , 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, David Woodhouse , Tom Lendacky , Nikunj A Dadhania , David Woodhouse , Michael Kelley , Thomas Gleixner 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. Reviewed-by: David Woodhouse 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 a9b6d3399c23..19da1a3d2126 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -972,9 +972,17 @@ 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(); @@ -994,7 +1002,7 @@ 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); -- 2.54.0.823.g6e5bcc1fc9-goog