From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0E0426F293 for ; Fri, 10 Oct 2025 19:24:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760124270; cv=none; b=kOLLhfiWAxAfCbU/46kcqDB7p8iigd8lexneDrgWMR6qXKlhGO4bBhZEUskvGAB2agQeP/+YhEvDdbbn6ndFTFI7FR5EcdbnZmotdU4RvrxtIfMwwbGe4D5NRCmAEUvAh0bO7HseMgbjjbrV7nrgloKRYit3mGAIlQse+aXq5Bc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760124270; c=relaxed/simple; bh=XnigtyMUFjn2MDY33dm/0+K54kKUpMQwSEWZ6YNSDTY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZZgf1KR6305TCxE6jjrmT9AypFROZfpbMzn+mb2rqCcQwcOveEfQzD7Srlfh5frrj8XbZwKht4SJeGrL1nln6UlHEFjLeRjlfDQCdSRq4JIMFN3AY8HL6Ami6AkLMO4MSbIwjB6pa86j9fDpQ+fY4IkkmFywykklYtuGz/2sPBY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=lhqe0o29; arc=none smtp.client-ip=198.175.65.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="lhqe0o29" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1760124268; x=1791660268; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=XnigtyMUFjn2MDY33dm/0+K54kKUpMQwSEWZ6YNSDTY=; b=lhqe0o293Tq1YbNpN6Eo6a7CJJWnocw4SFTPZsbrJ+kQNaG3XFnQASIz QJYFPISeJEwSbh8LEAbBLSq/MHjlHu/bEZ4DuH5K/WTY7nsqdIYF5yFvC 2dYl78r/5hWUb2FtDG7UZUJWogzoFy11mTebc8o7AszFpLO35ClRX3IPU YVgN69cfM/ASJ5U2LwZT+utnHnx8/fG2JNPtjFkR3jtBPKYiFYUojZgR8 AQOeg4DP3Xkl/K0OFRcuFs6RM+ss3eWChiMh/OhV0g9uvFI24ZqB96RMi Vrd7DevErkc+MgBuMM1PKMeSo7NcsoLO528F+NRGZZi8rHOJbLh41CI+W Q==; X-CSE-ConnectionGUID: MncuBOG1TLqLe88g6Qa2cA== X-CSE-MsgGUID: Wf1//R8STraYRWKzVtVT3g== X-IronPort-AV: E=McAfee;i="6800,10657,11578"; a="73789581" X-IronPort-AV: E=Sophos;i="6.19,219,1754982000"; d="scan'208";a="73789581" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Oct 2025 12:24:20 -0700 X-CSE-ConnectionGUID: GNt5g6FcTju+U0Toi1Jxxw== X-CSE-MsgGUID: 43B3lJb9TPSwrso3uN3zJg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,219,1754982000"; d="scan'208";a="180169146" Received: from smoehrl-linux.amr.corp.intel.com (HELO desk) ([10.124.221.161]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Oct 2025 12:24:19 -0700 Date: Fri, 10 Oct 2025 12:24:13 -0700 From: Pawan Gupta To: Josh Poimboeuf Cc: Borislav Petkov , "Kaplan, David" , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Dave Hansen , "x86@kernel.org" , "H . Peter Anvin" , Klaus Kusche , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] x86/bugs: Qualify RETBLEED_INTEL_MSG Message-ID: <20251010192413.5kx7hkysj3wsvxmq@desk> References: <20251006140442.GDaOPMemqB7SRJSHWL@fat_crate.local> <20251007182257.ywrqrrhgrtrviila@desk> <20251007221229.GAaOWQTadGWlZSeAo_@fat_crate.local> <20251007230821.5shpa3pusyzaohb2@desk> <20251009053336.ghcmhgsprtkgydas@desk> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Oct 10, 2025 at 12:19:12PM -0700, Josh Poimboeuf wrote: > On Fri, Oct 10, 2025 at 11:47:25AM -0700, Pawan Gupta wrote: > > > Instead, CONFIG_MITIGATION_SPECTRE_V2 could enable a submenu which then > > > allows the user to enable retpoline, IBRS on entry, etc, with each > > > having help text describing what generations of CPUs it would be the > > > default for, to help guide the user to choose sane defaults depending on > > > their CPU: > > > > > > * CONFIG_MITIGATION_SPECTRE_V2 > > > * CONFIG_MITIGATION_SPECTRE_V2_RETPOLINE > > > select CONFIG_BUILD_INDIRECT_THUNKS > > > * CONFIG_MITIGATION_SPECTRE_V2_IBRS > > > select CONFIG_BUILD_IBRS_ENTRY > > > > That would be good if a kernel is built for certain specific CPU(s). This > > may not be ideal for distro kernels. > > Why not? A distro can just enable everything: Ahh, right. > CONFIG_MITIGATION_SPECTRE_V2=y > CONFIG_MITIGATION_SPECTRE_V2_RETPOLINE=y > CONFIG_MITIGATION_SPECTRE_V2_IBRS=y > > and then if/when some older HW ages out of being supported by the > distro, they can start disabling things. Yup, that makes sense.