From nobody Tue Apr 7 19:55:54 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA534C04AA5 for ; Wed, 24 Aug 2022 23:42:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231707AbiHXXmZ (ORCPT ); Wed, 24 Aug 2022 19:42:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229763AbiHXXmQ (ORCPT ); Wed, 24 Aug 2022 19:42:16 -0400 Received: from mail-pl1-x649.google.com (mail-pl1-x649.google.com [IPv6:2607:f8b0:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77B164F65B for ; Wed, 24 Aug 2022 16:42:15 -0700 (PDT) Received: by mail-pl1-x649.google.com with SMTP id z18-20020a170903019200b00172dd6da065so7433916plg.14 for ; Wed, 24 Aug 2022 16:42:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:mime-version:message-id:date:from:to:cc; bh=GgNtt8XHsncrMgE4IbFRR5+V66rX8top3EG46fAYnRQ=; b=TkwbARh0dZMRE7NNmMKzQlT77SIZaFyNqwvglcl62fiCu+FaVN1DDQfnQNcqxl1vll PhPkHhlVODagqIz4tOQH43BaiM2ryWm+xZSXhAossnzohFLZSs+2A8oX3zn//MSOMIEB urVepvzcnyoWCw8fvVDJPxIuspFkyvYUrga4TCZ14ZMrMeVpUJJMfRYK5dD0aP+Sossv cU6qmYxY2kKa5AlDkc3R705d9YOAeNYmXbHg2hE5AnBn51FwPSreQ31kq4W8fi2ILaCi o5uUEvWoWzQnYliEL6hJCdZ55gk3zSKWuIxJm4oZY3fzNdDPICAZzK1Q09wgMrreTAl4 f5LA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:mime-version:message-id:date:x-gm-message-state :from:to:cc; bh=GgNtt8XHsncrMgE4IbFRR5+V66rX8top3EG46fAYnRQ=; b=6HzOJuaTBHYGqAC8iP945eWC/K8SPRP84gNoU3Abq3zxK1xZQZ6fg3nMXQWhm1a+4c 01wlqHHL4fbvJ1/6XtA33Zs3Ru4fhoALKofVdKKHKR8Ve9eqZeXQLVr97Sajd9Ulvbh6 E0b7kRfA8aclYGIURWMHJEYY/B7MLZU3pRF9dq8nDwYRs+MzVDB5Hpk1huQSLgq+Pn5f G3acRJOaN70c96PWOY+OnL60qqkaNL0ha3/jrGa/t7lgy8iFXoI/IeOVUg2SBDkPmeij 3hZtLilXixteWwU15zaovRAJ7v6Q/eC6btN8mJbIezy70jRZQMTTgH5us7UKSxQ6duaZ WHrw== X-Gm-Message-State: ACgBeo36K6lKVBUXr3F9daKWY9K3uTC2qKwcqrYjgoLVjhzih7Aw0j8B heCi2YQ50V8oCBI9udLaRjMWi/38VTM= X-Google-Smtp-Source: AA6agR6x5JpK2ntXNc8GBL28Et5asGmcl9MZgoMJ3jvSRbAgpvHAOAHK5SwfyRyWL8p/UZjWA2Fo4nhGynM= X-Received: from pshier-dev.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1b0b]) (user=pshier job=sendgmr) by 2002:a17:90b:33d2:b0:1fb:971b:c5e9 with SMTP id lk18-20020a17090b33d200b001fb971bc5e9mr1509609pjb.90.1661384534988; Wed, 24 Aug 2022 16:42:14 -0700 (PDT) Date: Wed, 24 Aug 2022 16:42:11 -0700 Message-Id: <20220824234211.1625026-1-pshier@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.37.1.595.g718a3a8f04-goog Subject: [PATCH v2] intel_idle: avoid tracing MSR writes while idling From: Peter Shier To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Jacob Pan , Len Brown , Peter Zijlstra , Michael Roth , Alexei Starovoitov , Josh Poimboeuf Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Peter Shier Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" With commit bf5835bcdb963 ("intel_idle: Disable IBRS during long idle"), enabling wrmsr trace with CONFIG_LOCKDEP causes "suspicious rcu_dereference_check() usage" warning because do_trace_write_msr does not use trace_write_msr_rcuidle. Change intel_idle_ibrs to use native_wrmsr to avoid tracing Sample warning: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D WARNING: suspicious RCU usage 6.0.0-dbg-DEV #7 Tainted: G S O Acked-by: Peter Zijlstra (Intel) Acked-by: Rafael J. Wysocki ----------------------------- arch/x86/include/asm/msr-trace.h:48 suspicious rcu_dereference_check() usag= e! other info that might help us debug this: rcu_scheduler_active =3D 2, debug_locks =3D 1 RCU used illegally from extended quiescent state! no locks held by swapper/59/0. stack backtrace: CPU: 59 PID: 0 Comm: swapper/59 Tainted: G S O 6.0.0-dbg-DEV = #7 Call Trace: dump_stack_lvl dump_stack lockdep_rcu_suspicious trace_write_msr do_trace_write_msr intel_idle_ibrs cpuidle_enter_state cpuidle_enter do_idle cpu_startup_entry start_secondary secondary_startup_64_no_verify Tested on skylake using: echo "msr:write_msr" >/sys/kernel/debug/tracing/set_event with and without patch. Signed-off-by: Peter Shier --- v2: - changed to avoid tracing v1: https://lore.kernel.org/all/20220823234353.937002-1-pshier@google.com/ drivers/idle/intel_idle.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index 3e101719689a..df129c73786f 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -187,12 +187,12 @@ static __cpuidle int intel_idle_ibrs(struct cpuidle_d= evice *dev, int ret; =20 if (smt_active) - wrmsrl(MSR_IA32_SPEC_CTRL, 0); + native_wrmsr(MSR_IA32_SPEC_CTRL, 0); =20 ret =3D __intel_idle(dev, drv, index); =20 if (smt_active) - wrmsrl(MSR_IA32_SPEC_CTRL, spec_ctrl); + native_wrmsr(MSR_IA32_SPEC_CTRL, spec_ctrl); =20 return ret; } --