From nobody Sun Feb 8 23:25:44 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 2D636C761A6 for ; Mon, 27 Mar 2023 08:27:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233391AbjC0I1Z (ORCPT ); Mon, 27 Mar 2023 04:27:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233240AbjC0I0z (ORCPT ); Mon, 27 Mar 2023 04:26:55 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3321655BE; Mon, 27 Mar 2023 01:25:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1679905500; x=1711441500; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=nd37h2vxkhLXg5jhh870M6BiFI8TxVn0dDXlR1ukIGo=; b=CaDQqz4biBKIUebVXOjp08vSpEgbZB5LohEewk8IHf34Z+alF3B6P/Rl q8jlLHgOIpAvGdkbPuBs+c3cpXLuezuXZonSguqepRAkLKqaT3MJfeqki FhYCZlbOYuHnUe66bWAZn50ARIv2+8/tcDQZ4ggca5OBRZ7UPCyxeABC/ eP+ioHpGvNByNNJ+PMlJjeEVlHow/JlWuHsUzyqDMYUD2KSEf2NMGUTIN aa/2BUUOli+Z91rBKsrDGANLyGhEo3jaJX3taQT43V2KLLIs8yEk/9wta Ki6pFhKZIkoRhlEYQ9GOPPjqZRB+4EOgTEjFfoAl5CTI9WNeCpeSR6vIa g==; X-IronPort-AV: E=McAfee;i="6600,9927,10661"; a="338930428" X-IronPort-AV: E=Sophos;i="5.98,294,1673942400"; d="scan'208";a="338930428" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2023 01:24:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10661"; a="713787165" X-IronPort-AV: E=Sophos;i="5.98,294,1673942400"; d="scan'208";a="713787165" Received: from unknown (HELO fred..) ([172.25.112.68]) by orsmga008.jf.intel.com with ESMTP; 27 Mar 2023 01:24:41 -0700 From: Xin Li To: linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, peterz@infradead.org, andrew.cooper3@citrix.com, seanjc@google.com, pbonzini@redhat.com, ravi.v.shankar@intel.com, jiangshanlai@gmail.com, shan.kang@intel.com Subject: [PATCH v6 32/33] x86/fred: disable FRED by default in its early stage Date: Mon, 27 Mar 2023 00:58:37 -0700 Message-Id: <20230327075838.5403-33-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230327075838.5403-1-xin3.li@intel.com> References: <20230327075838.5403-1-xin3.li@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Disable FRED by default in its early stage. To enable FRED, a new kernel command line option "fred" needs to be added. Tested-by: Shan Kang Signed-off-by: Xin Li --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ arch/x86/kernel/cpu/common.c | 3 +++ 2 files changed, 7 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 6221a1d057dd..c55ea60e1a0c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1498,6 +1498,10 @@ Warning: use of this parameter will taint the kernel and may cause unknown problems. =20 + fred + Forcefully enable flexible return and event delivery, + which is otherwise disabled by default. + ftrace=3D[tracer] [FTRACE] will set and start the specified tracer as early as possible in order to facilitate early diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index eea41cb8722e..4db5e619fc97 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1467,6 +1467,9 @@ static void __init cpu_parse_early_param(void) char *argptr =3D arg, *opt; int arglen, taint =3D 0; =20 + if (!cmdline_find_option_bool(boot_command_line, "fred")) + setup_clear_cpu_cap(X86_FEATURE_FRED); + #ifdef CONFIG_X86_32 if (cmdline_find_option_bool(boot_command_line, "no387")) #ifdef CONFIG_MATH_EMULATION --=20 2.34.1