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 920B5C433DB for ; Mon, 29 Mar 2021 23:41:06 +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 2F5AE6198A for ; Mon, 29 Mar 2021 23:41:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2F5AE6198A 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=ptGZ2o78Co8yCDCPQ1K7VbxIsHBEGCPYVF7EakpnvTU=; b=RVF9lvSjMt35ZVFMeCQcYeSA8 MWe7xGJbA9SEXJcfkB448gpZXytBSXz8lnANizuVRNx8cIy9jKhCxBFjEqu5DA3l2uhofZYXaT4y5 +72VwN65kNjdc/VBggmfnacsbzmF+989D6KTzyUCXWXK/1bjIyRYto34znwxBqnKymTPY9gZxQlpX IAxLVg8MLoO2eb2JSjITcP8AecrnOtNhOXFM207xatvH1Ie5GZ/F7SaSFFR9bZimo3iC9OEIDVOZk Yd7kHsYtoDOVKL+KH14iGZN2ID1HFDk4nV7yjp7i7k2ZCoLqH6DYVUm4FP9a07VG6bIHbH//eIJdW EoScFmyPA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lR1SL-001ys0-92; Mon, 29 Mar 2021 23:38:01 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lQvM6-000qx9-KT for linux-arm-kernel@lists.infradead.org; Mon, 29 Mar 2021 17:07:13 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8F5D76196C; Mon, 29 Mar 2021 17:07:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617037628; bh=Qo//hECiZwg243woaf//qYtt/SJegp+RIXSNnkO3AkQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RFjSmpcn6H7fKr/PPkUtHFcyl2rbcQI4Q322qJZGnmwduciDZzRq8qowNdAZDJJmP IaR5+Rc06SjyqSeEapM6Mcwv0/USHNUZ3uHNpB15YmfGAyM6ypw7101waiMMp3DbZw RzTPQUcyBVUDeOavsJLcNT44EMLZIqaS8RPKPwwhjYDlRfB26s4yoToP/4a0xF64r+ YtgmlYoFqzJiACguMCDhO359mo904eRGAq+wPjuXgbtJMjBK9aGFYz1HDQFj4R+IXe NnUAA+rWA8NA9mR8UiqXIiybyHjQa3Skel/fHC8Tc/xq/qc3ISY+qYFBGAgbSN1uN9 jsLySxCKLiedA== Date: Mon, 29 Mar 2021 18:06:57 +0100 From: Mark Brown To: Catalin Marinas Cc: Will Deacon , linux-arm-kernel@lists.infradead.org, Mark Rutland Subject: Re: [PATCH] arm64: Document requirements for fine grained traps at boot Message-ID: <20210329170657.GH5166@sirena.org.uk> References: <20210312154917.23263-1-broonie@kernel.org> <20210326115541.GC5126@arm.com> MIME-Version: 1.0 In-Reply-To: <20210326115541.GC5126@arm.com> 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_180711_426801_0BC58BD2 X-CRM114-Status: GOOD ( 19.33 ) 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="===============0905696908202962615==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============0905696908202962615== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="/Gk0KcsbyUMelFU1" Content-Disposition: inline --/Gk0KcsbyUMelFU1 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Mar 26, 2021 at 11:55:41AM +0000, Catalin Marinas wrote: > On Fri, Mar 12, 2021 at 03:49:17PM +0000, Mark Brown wrote: > > + - HAFGRTR_EL2, HDFGWTR_EL2, HDFGRTR_EL2, HFGWTR_EL2, HFGRTR_EL2 and > > + HFGITR_EL2 must be initialised to 0. > While this requirement is correct, documenting such individual registers > doesn't scales well. You may run a 5 year old kernel on a newer CPU and > we can't predict which control registers have been added and what > side-effect they have. The architecture, at least for the above I'm not a huge fan of writing things this way either, I'd inferred that this sort of minimal and specific thing was the idiom desired so was trying to follow. > Can we instead have a broad statement regarding any EL1/EL2 registers > that they should be either rest to 0 or to the architectural (warm) > reset value as per the ARM ARM? Or something like any feature must be > disabled by default at the EL1/EL2 control registers level and this > would imply the fine-grained traps. > We currently have this statement: > All writable architected system registers at the exception level where > the kernel image will be entered must be initialised by software at a > higher exception level to prevent execution in an UNKNOWN state. > The "prevent execution in an UNKNOWN state" needs to be clearer. The > above should also include exception levels _below_ the one where the > kernel is entered. It doesn't help if KVM is old and has no clue of new > EL1-specific registers. Right, I think both those things are needed to cover the general case. The exception levels bit is hopefully straightforward but wording for the clarification bit is more tricky - I'll try to come up with something. --/Gk0KcsbyUMelFU1 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmBiCTAACgkQJNaLcl1U h9AhpQf/e7YuwegBELuTJwnn5JFNxGnDGkK4Pvug2fbixHmKdBwFHAlKH09nmKL+ obSpHoU3OWlkAc3dwWhQ5KfpLW3a+v1MPSaxqIygHvG2ub8Oj0m1gX8aZ2sA9F8J pPZY+kANn55ti69BdQMx53o0Q9fXyk0K5rGtNnBAus5oivBNLcFjp86e/P1jcsVq e4NGNb1H/HWVE/w9q79+hGqKY3r1/6Kdelhc6V3r7vqgvK5TKrOH+SloLo6KXen1 LbM2T+vX48Yor59mloUJKWoY0xERIjvy9eshU3ERLa8M3livUyKY7CfRdbdyfMP6 1zvJRd8+qIVg9JoiFDIKGo8myG4LdQ== =qcI7 -----END PGP SIGNATURE----- --/Gk0KcsbyUMelFU1-- --===============0905696908202962615== 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 --===============0905696908202962615==--