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=-5.7 required=3.0 tests=BAYES_00,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 7EADBC433C1 for ; Mon, 29 Mar 2021 19:45:03 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 0B182617C9 for ; Mon, 29 Mar 2021 19:45:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0B182617C9 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+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=desiato.20200630; h=Sender:Content-Type: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:Cc: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=nYCkEjpjEOf++vAQXDzzYWNGyXEPXtk5SeN/6aJfGnk=; b=DFJ9jACAoiD2ZPFcSyEokkYXU 8wNN4ydtk7SUBOl02IX2k6btkP6zc9XfvqVTACTmngk7DsBOlx6Vz02TNz18Zo2JGMw1OJgbwYHbD KzRkT+0uB+4/rFvf1aBHfLPSzHMGltozEHUx1Rdrv27zRG1UinGtgpD4WsbI9f3EW5zHyEB1corAK /2t/8c2kz9Ckkp7KLdIN/rqb9z0BGLKT7V5vhw0pIwgD9TNKdbiKP6EZMYQslEuiC8NnhYv4c0LNx w9LyWGPUZZYng6AWmP+lK5/O755Dqy09x3/6oVlza8pCkGidXh2KaEZXodJRvr5dIAUQ0ynNTZMSf yscie5/tA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lQxmg-001Hlu-46; Mon, 29 Mar 2021 19:43:05 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lQqxu-000eNX-V1 for linux-arm-kernel@lists.infradead.org; Mon, 29 Mar 2021 12:25:57 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 26E2E60C3D; Mon, 29 Mar 2021 12:25:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617020747; bh=k5Xo7M8YxCTgQvq3oZZBxXBwEdqTdwL6eQKAec9yXJU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qvawBv+9SPs/+va6nFqAL928xh1AKYlFI2hLBMAaMkDSqM8EuzkQ4KsfccH3JrutQ nb3ys53hyD42W0bEKl1TU096eDZN9t8ZK5cSrzpPpn6TsmMTsjwA77Jd3scMNwsD3y au7q7b2r0W5TTl12DqKC2FlSw7auOwtgqQcMb27p7hmSiByHJT7QSQPjD2ocpVXxwY 1k05lCLxs5SFxj9X2HPXVwvmMEMuurdne5Z4CGcI6EyEw7sqpi/l2b3KDC+SwC4iPt FEy5saJxiFNwwD0aFytpWFN6iraZF9T9KcRGvo5/mtjrBG9MmUDFUzJo4mpijfVPl+ PahJurA+q4OEw== Date: Mon, 29 Mar 2021 13:25:36 +0100 From: Mark Brown To: Will Deacon Cc: Catalin Marinas , linux-arm-kernel@lists.infradead.org, Mark Rutland Subject: Re: [PATCH] arm64: Document requirements for fine grained traps at boot Message-ID: <20210329122536.GA5166@sirena.org.uk> References: <20210312154917.23263-1-broonie@kernel.org> <20210326115541.GC5126@arm.com> <20210329103126.GE3207@willie-the-truck> MIME-Version: 1.0 In-Reply-To: <20210329103126.GE3207@willie-the-truck> X-Cookie: Never give an inch! 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-20210329_132555_225962_C646D0A9 X-CRM114-Status: GOOD ( 13.84 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============0620080936489773668==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============0620080936489773668== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="9amGYk9869ThD9tj" Content-Disposition: inline --9amGYk9869ThD9tj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Mar 29, 2021 at 11:31:27AM +0100, Will Deacon wrote: > One thing I don't understand about the registers listed here is that we're > requiring firmware to initialise them when the kernel is entered at EL2. But > they're *_EL2 registers, so why can't the kernel initialise them itself? The > fewer dependencies on firmware, the better. Well, there's nothing stopping us doing both - that's the most robust thing. Relying on the kernel alone to do this has the old kernels on new systems issue, and there's always going to be some section of code running before we manage to go through and enumerate features then reset the system registers even if we run that code very early. With something like traps it seems especially relevant, it's more of a "could affect anything" kind of thing than something where we can initialize the feature before we start using it. --9amGYk9869ThD9tj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmBhx0AACgkQJNaLcl1U h9CdfQf/bRcweazC6oyUsHghnmRIM8erw3viRkkP6BbJMksKtIVpk/av4+QEIt03 qXUFNBgZwtT3Xm/OrJHRn9knUsWLXsEx4UX6VkqKzZFzYEP1i3Qgt0mf/fk6gdaN nd3ucc13MJrO+3JJhJ1Xe+p3obruBqXGXsDg4Y4NU0/JI+PitPrx8ZFArNY4z4c7 nfZLobV4GmqfYmYw6JMqvtsJKZL+xeQqVEpElcaSIHDW0wafbJhhvKLNwqncBUqq NlqDcAa35Q7xEQIJJvY+HxZmf+TuY1K/yOBFWabJflWh6FdWQuCZ+DuHeSq1jpnf s+zR6r07aa0UcAQteWr857td9meVGw== =FyZM -----END PGP SIGNATURE----- --9amGYk9869ThD9tj-- --===============0620080936489773668== 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 --===============0620080936489773668==--