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=-17.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 49DACC433E0 for ; Fri, 12 Mar 2021 15:55:06 +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 CA44864FE0 for ; Fri, 12 Mar 2021 15:55:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA44864FE0 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-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=yb6R1uK2C+BMckqWSXFScwhQH4rWswzhhYazAlSnbjI=; b=HKeV3jL4BO3c2sIzO5qRUdF/oQ p9kMWy8lJrKpgojj9tJHTTuxNn59bBqC4HhoRFMih0xC9wYLqmphU18Kn0uuFvXAkPbh7rLMiJCiS S7EeRGRGl4OuovkzXCxHoyz5FI47zmxa2GSSs4/kREDME1uJSHYhLgve5PmoScOoiDlf8YfGyiU0Y FzZC2N0CWJERR++7NWzfwlnwridGo2qXutEZbkr1cFY/6UfzjUwTC5eATMMzyf9a9i/LhRlgiywJ1 t693HBIrIpYEI2L3boVA17F21xpOcCuA0uiLrQWS2iMjCL5EHxcjpCpUnCqrKBSokma7XjLS/j/Fd d6Kmu0sQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lKk6j-00BsUE-0J; Fri, 12 Mar 2021 15:53:45 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lKk6b-00BsSx-Ly for linux-arm-kernel@lists.infradead.org; Fri, 12 Mar 2021 15:53:39 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 57DFE64FE0; Fri, 12 Mar 2021 15:53:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615564415; bh=xkFxOnbeoGW384UxdJPzlI0dR5Ip0MCRI1VDRRNIlhA=; h=From:To:Cc:Subject:Date:From; b=hETGCD9n7PTOgsQk5d4TMCNAHGSRMPOVtiTuyhrgUkVbVqzg4src/fOtkzDb3YFEy bvIwyQQCjwrhCaU4Xi9ldQXHmxBccwGj4HSzcCs5M+2zRkxRZ0Cl2tLfCNm866Qh9x focp3/CBVzoU4A2nsHo21QF4XD1f7BPg4JQfqIFaSpGqGCH+dH6rpwgj4ZDSKjTYWU 6C6V5mGOti8EHnyguCUtF7PF1R3xIY6Iht222KZ2ucasB6pjmxN2k13mWF1npk/ybW eKKrN2RWv87rtMLAdJHfk55HeJW9uhApicvS/nyiIkB9ZUumPQRkHW60QyC4KulzAo dIXSWlVPuFVmA== From: Mark Brown To: Catalin Marinas , Will Deacon Cc: linux-arm-kernel@lists.infradead.org, Mark Brown Subject: [PATCH] arm64: Document requirements for fine grained traps at boot Date: Fri, 12 Mar 2021 15:49:17 +0000 Message-Id: <20210312154917.23263-1-broonie@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-Patch-Hashes: v=1; h=sha256; i=3zwHCBz+BRy4MS4wz7TFS0H1AKX3IEJHanve+vG8FAg=; m=J6Fg5icrJ/SNG5y0HcjLu4ZZTMOUAkYMprlDXeaLYlA=; p=xpNtKjyVk1LdtYayTdg04LtSmu29ogsmYBHQvEvKwBo=; g=a8b166299c6fa0ecd01509a4b63d8cf106feda60 X-Patch-Sig: m=pgp; i=broonie@kernel.org; s=0xC3F436CA30F5D8EB; b=iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmBLiDMACgkQJNaLcl1Uh9D9vQf/VeF xaRk0qOGSHrPaEeLrAWVWA6lr2iD2azKaoq1EMZCdx7tEY2iCe9aP9wlYBG8qj1cUEgBfb/SqLdXn G+W/uHceDXffg8GmucW5FTQTcz88gA8OPVbl9yCHu7NvCIOEGpH4L61OI58VdiVzpCy9xdvjsukcX Qk7QnHubQCdWFgMPcwatt/L8jX5s8aDhDERj/bFEmoXcpDyVChafPpuMut1bXZfICJoMcF0XM9OkN kafnI/IJAO8duKFSiHVn+bH2qvofnrOITMzUjBL/eC9eMmpAlt5uar1MxFhck6C+v84+Evs61Z3b9 p7p5fAucGSKpoYc8Ee89nbnpoSH00xg== X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210312_155338_015464_335D7949 X-CRM114-Status: UNSURE ( 9.65 ) X-CRM114-Notice: Please train this message. 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: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The arm64 FEAT_FGT extension introduces a set of traps to EL2 for accesses to small sets of registers and instructions from EL1 and EL0. Currently Linux makes no use of this feature, explicitly document that it should be disabled when entering the kernel at EL2 (as is the architectural default) to help avoid surprises. Signed-off-by: Mark Brown --- Documentation/arm64/booting.rst | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst index 7552dbc1cc54..1efc2d3023bb 100644 --- a/Documentation/arm64/booting.rst +++ b/Documentation/arm64/booting.rst @@ -270,6 +270,13 @@ Before jumping into the kernel, the following conditions must be met: having 0b1 set for the corresponding bit for each of the auxiliary counters present. + For CPUs with Fine Grained Traps (FEAT_FGT) extension present: + + - If the kernel is entered at EL2: + + - HAFGRTR_EL2, HDFGWTR_EL2, HDFGRTR_EL2, HFGWTR_EL2, HFGRTR_EL2 and + HFGITR_EL2 must be initialised to 0. + The requirements described above for CPU mode, caches, MMUs, architected timers, coherency and system registers apply to all CPUs. All CPUs must enter the kernel in the same exception level. -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel