From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C617C47404 for ; Fri, 11 Oct 2019 13:47:03 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4A8D22064A for ; Fri, 11 Oct 2019 13:47:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="rMHPfMis"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sirena.org.uk header.i=@sirena.org.uk header.b="JuBmJcQ9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4A8D22064A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lQvH8RZ6/ZproYJ7K+hSSRvKbffeRh3HoM5HFIPfrVE=; b=rMHPfMisPSTmPwmYO75zrh2a2 iD3GbhQJLm0qhMTFXNH5iBxMEX13Ez7toBlnCK3bbkP8MD6to7tSkzQgr6C0im3HXUf29kC1/ryAn MhtfUsmHMoWc5m7uR7RxvGb2qXMll3mJ7gTcqxh2q6BYyqDczP2AzZwskcokRdi2y2UPC1fqLLlmg FrOUs/0OO3k8js2cIiO95WSP44b/KO9XOgPSUTWZc6xUqXIJO9ogvSGn3AnEU2aVcdBfpyRzP1u3I grOFS8vsY/PSSk3sZZQsMGstf3Rog6qqSixCx6MaDDgVjwyRxtFHmkoc6SAQRlfxFq4LfxMSP2CuR e1WY+G5SA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIvG2-0002lK-Qt; Fri, 11 Oct 2019 13:47:02 +0000 Received: from heliosphere.sirena.org.uk ([172.104.155.198]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIvG0-0002ko-Ca for linux-arm-kernel@lists.infradead.org; Fri, 11 Oct 2019 13:47:01 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Ssipnciy5BWOnB8+GsrXMhGdvQLP40vXK/KUi8wveJQ=; b=JuBmJcQ9V5mPu1ool8nCXMO8Z KX4xN4sNtepfGf/uLdvovJXA7tIT2Sq1jV+mAK75rnK7rvF5yFMOK3smCzBrfkqJdEH/YBEVOkAaP 3pFqWHKsJLTIJMLFK/H1vWnN84QiHcOpJLmTIMLWLClQd/qiArngRGPDdc4mcfDdAB08o=; Received: from fw-tnat-cam7.arm.com ([217.140.106.55] helo=fitzroy.sirena.org.uk) by heliosphere.sirena.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1iIvFw-0005s3-Lb; Fri, 11 Oct 2019 13:46:56 +0000 Received: by fitzroy.sirena.org.uk (Postfix, from userid 1000) id 70485D0019E; Fri, 11 Oct 2019 14:46:55 +0100 (BST) Date: Fri, 11 Oct 2019 14:46:55 +0100 From: Mark Brown To: Will Deacon Subject: Re: [PATCH v2 1/2] arm64: Add initial support for E0PD Message-ID: <20191011134655.GI4741@sirena.org.uk> References: <20190814183103.33707-1-broonie@kernel.org> <20190814183103.33707-2-broonie@kernel.org> <20191010161317.GD24793@lakrids.cambridge.arm.com> <20191011111715.GH4741@sirena.org.uk> <20191011114013.ovvs36rrolkn2hzv@willie-the-truck> MIME-Version: 1.0 In-Reply-To: <20191011114013.ovvs36rrolkn2hzv@willie-the-truck> X-Cookie: Void where prohibited by law. User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191011_064700_442365_C3472B4F X-CRM114-Status: GOOD ( 13.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Catalin Marinas , linux-arm-kernel@lists.infradead.org, Suzuki K Poulose Content-Type: multipart/mixed; boundary="===============3517198089253659939==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============3517198089253659939== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="YrQNB5Deg1WGKZi3" Content-Disposition: inline --YrQNB5Deg1WGKZi3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Oct 11, 2019 at 12:40:13PM +0100, Will Deacon wrote: > On Fri, Oct 11, 2019 at 12:17:15PM +0100, Mark Brown wrote: > > It does - the main motivation for doing it as a local feature was > > to avoid the regression with systems with late CPUs that lack the > > capability which Will was concerned about but I'm not sure how > > realistic such systems actually are. > I think we need to handle the case where not all CPUs support ExPD :( > It's not like E0PD is something critical like support for a particular page > size, so I think it's a tough sell for SoC integrators to ensure that it's > matched up. That's fine, we handle them by falling back to KPTI if we detect any non-E0PD CPUs. The only difference in the end result between doing this by making it a system wide capability and doing it as a weak local capability is what happens if the first CPU that appears without E0PD is a late CPU then instead of accepting the CPU and enabling KPTI we will reject the CPU. --YrQNB5Deg1WGKZi3 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl2gh84ACgkQJNaLcl1U h9Ca9wf/WxHTH4xdIObomAb5ewDIX93+YF+YLWxTZCWjegnoDAjB2WB7kzgsrWEr 2YHQ2rj2q45Fg4jF4Vh8BbYrcZ86ki9ymAFGKk6WvftRvoPjjVP4xQuSpWxZkLRA xb3LVa9y4bOYGQnOu885IUwpy6TmIyKO6ApDqaHbd12RN9Vg7S5jPRMEEXTBhqof ChzFKNW3FZ0srBHzEopQ/JrLjH9DvRMI8pWZm++N2Tk1fETyY9SrutLRODTjty3z /fUHHHX5c0zqRzyCh0DvCxZHwy3pJ4jnljMPPpuHjC/jFhzF2dU3DO5tpdHPL+Wg CCIHvAqaCQBWDzf2dusFPfEbUr/FmQ== =Swfk -----END PGP SIGNATURE----- --YrQNB5Deg1WGKZi3-- --===============3517198089253659939== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============3517198089253659939==--