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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3904DC433EF for ; Tue, 12 Oct 2021 14:20:29 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id AC5676101D for ; Tue, 12 Oct 2021 14:20:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AC5676101D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 353434B089; Tue, 12 Oct 2021 10:20:28 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id uwOXLTktJ+9N; Tue, 12 Oct 2021 10:20:27 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 0C0404B08B; Tue, 12 Oct 2021 10:20:27 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 329284B089 for ; Tue, 12 Oct 2021 10:20:26 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id VlDguj37myAi for ; Tue, 12 Oct 2021 10:20:25 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 0A10B49DE7 for ; Tue, 12 Oct 2021 10:20:25 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 464F4608FE; Tue, 12 Oct 2021 14:20:23 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1maIdh-00GHHb-2V; Tue, 12 Oct 2021 15:20:21 +0100 Date: Tue, 12 Oct 2021 15:20:20 +0100 Message-ID: <87ee8qpbob.wl-maz@kernel.org> From: Marc Zyngier To: Andrew Jones Subject: Re: [PATCH] KVM: arm64: Fix reporting of endianess when the access originates at EL0 In-Reply-To: <20211012120040.4tfkzlm7uju2n3sa@gator> References: <20211012112312.1247467-1-maz@kernel.org> <20211012120040.4tfkzlm7uju2n3sa@gator> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: drjones@redhat.com, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: linux-arm-kernel@lists.infradead.org, kernel-team@android.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Tue, 12 Oct 2021 13:00:40 +0100, Andrew Jones wrote: > > On Tue, Oct 12, 2021 at 12:23:12PM +0100, Marc Zyngier wrote: > > We currently check SCTLR_EL1.EE when computing the address of > > a faulting guest access. However, the fault could have occured at > > EL0, in which case the right bit to check would be SCTLR_EL1.E0E. > > > > This is pretty unlikely to cause any issue in practice: You'd have > > to have a guest with a LE EL1 and a BE EL0 (or the other way around), > > and have mapped a device into the EL0 page tables. > > I wonder if that's something a usermode network driver might want? I don't know what it wants, but I don't want it the first place! Think of what a kernel would need to do to run its userspace in a different endianness... Userspace device access is just an additional headache. Whoever does this needs urgent medical attention! > Reviewed-by: Andrew Jones Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm