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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 52CF5C35254 for ; Mon, 10 Feb 2020 18:03:44 +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 0CE0820715 for ; Mon, 10 Feb 2020 18:03:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="QroFJ3XI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0CE0820715 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com 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-Transfer-Encoding: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-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=J83xKZoM+l0kfWPIUB7DMvVBQFVD+Q0zJN+nb2Z8rn0=; b=QroFJ3XI0RDWEy q7uoD3bVnGC7Hu7lc1ZQpeb9n9onT30Po9XuodWeB2YRqJslk3yIoiqOhRNUyCFJijio9oEfgOZm2 FwP4tjgEo2azBhRKYPqSt/Hk8B2WqMg7fyT+JY/66ohyPAfLrpeyLN3vtLCElSHE/ipWEc9ZZxslT Ifag+2J44gK60ZLOs+1+BfQji6e2IqActTYAexOiAMrXlO4LFDVNLuOWbvxuh6waCDq80Dfk5j24W 0jq99INcZPYxwZ1JAndYMHtYb1YYXSm3GPShF7XGUNhawp9k8q/usZRlS0SYjGD0y26BALlimNZTD gNtaMQJ6ikNvVXLOseQw==; 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 1j1DPE-00047G-TG; Mon, 10 Feb 2020 18:03:36 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1DPB-00046v-MI for linux-arm-kernel@lists.infradead.org; Mon, 10 Feb 2020 18:03:35 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EE7601FB; Mon, 10 Feb 2020 10:03:32 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A0C3D3F68F; Mon, 10 Feb 2020 10:03:30 -0800 (PST) Date: Mon, 10 Feb 2020 18:03:28 +0000 From: Mark Rutland To: Will Deacon Subject: Re: [PATCH v7 09/11] arm64: disable SCS for hypervisor code Message-ID: <20200210180327.GB20840@lakrids.cambridge.arm.com> References: <20191018161033.261971-1-samitolvanen@google.com> <20200128184934.77625-1-samitolvanen@google.com> <20200128184934.77625-10-samitolvanen@google.com> <6f62b3c0-e796-e91c-f53b-23bd80fcb065@arm.com> <20200210175214.GA23318@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200210175214.GA23318@willie-the-truck> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200210_100333_766850_8C830A85 X-CRM114-Status: GOOD ( 12.05 ) 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: Kees Cook , Ard Biesheuvel , Masahiro Yamada , Catalin Marinas , Jann Horn , Nick Desaulniers , linux-kernel@vger.kernel.org, Steven Rostedt , Miguel Ojeda , clang-built-linux@googlegroups.com, James Morse , Masami Hiramatsu , Sami Tolvanen , Marc Zyngier , kernel-hardening@lists.openwall.com, Laura Abbott , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Feb 10, 2020 at 05:52:15PM +0000, Will Deacon wrote: > On Mon, Feb 10, 2020 at 05:18:58PM +0000, James Morse wrote: > > On 28/01/2020 18:49, Sami Tolvanen wrote: > > > Filter out CC_FLAGS_SCS and -ffixed-x18 for code that runs at a > > > different exception level. > > > > Hmmm, there are two things being disabled here. > > > > Stashing the lr in memory pointed to by VA won't work transparently at EL2 ... but > > shouldn't KVM's C code still treat x18 as a fixed register? > > My review of v6 suggested dropping the -ffixed-x18 as well, since it's only > introduced by SCS (in patch 5) and so isn't required by anything else. Why > do you think it's needed? When EL1 code calls up to hyp, it expects x18 to be preserved across the call, so hyp needs to either preserve it explicitly across a transitions from/to EL1 or always preserve it. The latter is easiest since any code used by VHE hyp code will need x18 saved anyway (ans so any common hyp code needs to). Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel