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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 75854C4360F for ; Fri, 22 Feb 2019 11:51:35 +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 3F7D220652 for ; Fri, 22 Feb 2019 11:51:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="d8XKav99" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3F7D220652 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:MIME-Version:References:In-Reply-To: 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=Sit+FXCK1PXqtRWwh4Wv9E7j956MPJtHDf2kiqug11w=; b=d8XKav99Id7RDz WjQTPxVwQ/qobSviY31AATRBW5u6vdgjEBBVigDUWIOPZ3gonh7BsWcSAX/5toAiIok95xgtv92YS VRwdSEJZvLbyglo9LcQn/Oega+rxGZvSOhCJxOLdilb9kMK6nqKiJNjDbAq5wO7aCk/Ujxvmi3N6j OvPyupXvfzJrewzPHmx1mBezMWvIpWfJ68Us/8ic1boeFxB3mZnxrHbuJpIXRZVOpf1s1uPuEzDkr +M3dbESuyWPFX5TIj4oTPL7Arv3BHwFqE7Oq1vdiMqruHk3y2dVS5FJ6gP+bk4gQazfrXRst9G3XH i3R1lq0qpuJ5SWTr7XFA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gx9MZ-0001yD-O6; Fri, 22 Feb 2019 11:51:31 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gx9MW-0001xW-3m for linux-arm-kernel@lists.infradead.org; Fri, 22 Feb 2019 11:51:29 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5D32CA78; Fri, 22 Feb 2019 03:51:25 -0800 (PST) Received: from why.wild-wind.fr.eu.org (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A9D713F5C1; Fri, 22 Feb 2019 03:51:23 -0800 (PST) Date: Fri, 22 Feb 2019 11:51:19 +0000 From: Marc Zyngier To: Dave Martin Subject: Re: [PATCH] KVM: arm64: Fix architecturally invalid reset value for FPEXC32_EL2 Message-ID: <20190222115119.170cb5fc@why.wild-wind.fr.eu.org> In-Reply-To: <20190222105604.GB3567@e103592.cambridge.arm.com> References: <1550749352-2315-1-git-send-email-Dave.Martin@arm.com> <20190222100103.03fb773d@why.wild-wind.fr.eu.org> <20190222105604.GB3567@e103592.cambridge.arm.com> Organization: ARM Ltd X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190222_035128_161044_A616A657 X-CRM114-Status: GOOD ( 17.75 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Julien Thierry , Suzuki K Poulose , Christoffer Dall , stable@vger.kernel.org, James Morse , kvmarm@lists.cs.columbia.edu, 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 Fri, 22 Feb 2019 10:56:07 +0000 Dave Martin wrote: > On Fri, Feb 22, 2019 at 10:01:03AM +0000, Marc Zyngier wrote: > > On Thu, 21 Feb 2019 11:42:32 +0000 > > Dave Martin wrote: > > > > > Due to what looks like a typo dating back to the original addition > > > of FPEXC32_EL2 handling, KVM currently initialises this register to > > > an architecturally invalid value. > > > > > > As a result, the VECITR field (RES1) in bits [10:8] is initialised > > > with 0, and the two reserved (RES0) bits [6:5] are initialised with > > > 1. (In the Common VFP Subarchitecture as specified by ARMv7-A, > > > these two bits were IMP DEF. ARMv8-A removes them.) > > > > > > This patch changes the reset value from 0x70 to 0x700, which > > > reflects the architectural constraints and is presumably what was > > > originally intended. > > > > > > Cc: # 4.12.x- > > > Cc: Marc Zyngier > > > Cc: Christoffer Dall > > > Fixes: 62a89c44954f ("arm64: KVM: 32bit handling of coprocessor traps") > > > Signed-off-by: Dave Martin > > > > Applied to -next. > > > > Thanks, > > Thanks. > > I have a patch for <= v4.11 which I can send to stable once this patch > reaches torvalds/master. > > Is it worth it though, in your opinion? I don't think it has much value. To be honest, this patch mostly serves as documentation, as any implementation worth its salt will honour the RES0/RES1 properties. I've kept the cc stable in your original patch, but arguably it doesn't fix anything real. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel