From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793607689; b=vXJyVSAd1UmAs4j8rqP/u/3DTyiHxzv8s5yrU4LhJy70RecaBb+ohAvPuoHSsdIcsdVD vjEknpXW7maTWGdq6AV1EbZee0B3R75Onac2c4W+vt5zpMb8UUt1cXRMnC6Tlq0JBiRBF +R6+JVsgsOllM9pOiJ9aaOtsI80rMT4Cp3GUXcEHhSbJh7MoM3L10LvcWyhz0h9Nx9pah aG5+UZ4OgSEHUCgS6is9J2LYQctJLRgejAy/wQGBVRb2uAqexZnNcksjRkdOKRlMBU9G/ YBiS7LyYPw6kgRFNyymQfFvCLQ/CJNlCI0j8jwJf3s4J55UOjaSUVuzNsWuwzwpGyQw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793607689; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=AvJtfbiV6SfMnq20pOgeXr9a5dTB4ppz5wJgI3CXFy0=; b=wcAf+VCZlAZtHTi22D+osr7nG0AvVO/hPBTaaIRBpWHvlHTti93wqzKn0l6hrlb6Qzk4 K1DPte4Gydg/+n/bg4BGPbKZnu98E3dsnY/X8yg+kEvIbo8VJV6nop4ZDqUx9uGqk1Fws 0VTONGx1PRo/3Onnc9ChUOjxRM07hYrfyHY0yDruhUZUOmN3Gk/apNF7JoewMrksrbCRv 1FT9R3VW74Q5XGDo0yL/p+TkxE/5QMZo4wCrXmseWWbTS0Aq0PLx85XX+7Ffo0EvpUoyr coqnXQWM5zQphg4FANsGRjU1R1DDsYz6aJEEXh8dypP1nPyRuPU3V/UlKWfrKjhEBAQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=b8W3Fa6n; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F381860A2611 for ; Mon, 2 Nov 2026 08:21:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=b8W3Fa6n Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55EB71F00A17; Mon, 2 Nov 2026 08:21:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793607688; bh=AvJtfbiV6SfMnq20pOgeXr9a5dTB4ppz5wJgI3CXFy0=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=b8W3Fa6n0lMSA8SK5GoC4/PatsM8z5cX3DXZ/qvtkzbuoFCk+LxgU5iAP/UfZZzIV 4TirUVjOKsq5SNFpA2sZWxtHLhDtc0tnFtUBJWZ8B6KdllKCmmeBa3Cg4IU6W9X/gn AkAwj2qHlBHSKj7lTfTywbt0epW+brm8BWo2AhTRrhyckySfYPl7MRsNMepVUNRp2M JWlcU46HnYJgOdCp90gFNTONqz2h0v9UOyA7uljuG9DY4fnw5E8g/UQYR0QA2O94G6 mnuFy9OD+7X1F62Dr4d8DLxrah1hoIJQzwBqKgIkEuhwGgSGZ8tay92FKNDgBIWXAl ZLXiXuFDTTlvA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH 4/6] perf/x86/intel/pt: Clear TraceEn in hardware in cpu_emergency_stop_pt() Reply-To: sashiko-reviews@lists.linux.dev To: "Adrian Hunter" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20261102074039.26983-5-adrian.hunter@intel.com> References: <20261102074039.26983-1-adrian.hunter@intel.com> <20261102074039.26983-5-adrian.hunter@intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 02 Nov 2026 08:21:27 +0000 X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > cpu_emergency_stop_pt() stops tracing through pt_event_stop(), which > assumes the software state accurately reflects whether tracing is > enabled. That assumption can fail when a crash NMI interrupts > pt_config_start(). >=20 > pt_config_start() sets TraceEn in IA32_RTIT_CTL before updating > event->hw.aux_config. If a crash NMI arrives in that window, > pt_config_stop() sees TraceEn clear in aux_config and skips the MSR > write needed to disable tracing. Tracing remains active in hardware. >=20 > Alternatively, an earlier NMI in the same window can stop the event > without restarting it, for example a group throttle calling > pt_event_stop(event, 0), or a PT PMI for which perf_aux_output_begin() > fails. pt_config_stop() again skips the write, so the event is stopped > only in software: TraceEn remains set in IA32_RTIT_CTL, and > [ ... ] > Fixes: 8e105a1fc2a0 ("perf/x86/intel/pt: Factor out pt_config_start()") > Fixes: 25e8920b301c ("perf/x86/intel/pt: Add sampling support") > Fixes: 08c7454ceb94 ("perf/x86/intel/pt: Add support for pause / resume") > Fixes: 2e17bf3a469a ("perf/x86/intel/pt: Fix stop/start with no update") > Signed-off-by: Adrian Hunter Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261102074039.2698= 3-1-adrian.hunter@intel.com?part=3D4