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=-4.0 required=3.0 tests=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 D2C99C43381 for ; Thu, 28 Mar 2019 10:13:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7DE621773 for ; Thu, 28 Mar 2019 10:13:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726238AbfC1KNN (ORCPT ); Thu, 28 Mar 2019 06:13:13 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:41738 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725779AbfC1KNN (ORCPT ); Thu, 28 Mar 2019 06:13:13 -0400 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 7AFDC15AB; Thu, 28 Mar 2019 03:13:12 -0700 (PDT) Received: from [10.162.0.144] (a075553-lin.blr.arm.com [10.162.0.144]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F01F33F59C; Thu, 28 Mar 2019 03:13:09 -0700 (PDT) Subject: Re: [PATCH v7 9/10] KVM: arm64: docs: document KVM support of pointer authentication To: Dave Martin Cc: Kristina Martsenko , Marc Zyngier , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Ramana Radhakrishnan , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org References: <1552984243-7689-1-git-send-email-amit.kachhap@arm.com> <1552984243-7689-10-git-send-email-amit.kachhap@arm.com> <23e4a9d4-e9e1-2c1f-32ce-e7fd96080437@arm.com> <20190327104428.GV3567@e103592.cambridge.arm.com> <20190327135058.GW3567@e103592.cambridge.arm.com> From: Amit Daniel Kachhap Message-ID: <82d60b1e-d08b-a8f8-457a-c9ead0378e0e@arm.com> Date: Thu, 28 Mar 2019 15:43:07 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190327135058.GW3567@e103592.cambridge.arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dave, On 3/27/19 7:20 PM, Dave Martin wrote: > On Wed, Mar 27, 2019 at 05:19:28PM +0530, Amit Daniel Kachhap wrote: >> Hi, >> >> On 3/27/19 4:14 PM, Dave Martin wrote: >>> On Mon, Mar 25, 2019 at 08:05:49PM +0000, Kristina Martsenko wrote: >>>> On 19/03/2019 08:30, Amit Daniel Kachhap wrote: >>>>> This adds sections for KVM API extension for pointer authentication. >>>>> A brief description about usage of pointer authentication for KVM guests >>>>> is added in the arm64 documentations. >>>>> >>>>> Signed-off-by: Amit Daniel Kachhap >>>>> Cc: Mark Rutland >>>>> Cc: Christoffer Dall >>>>> Cc: Marc Zyngier >>>>> Cc: kvmarm@lists.cs.columbia.edu >>>> >>>> I think it makes sense to also update the Kconfig symbol description for >>>> CONFIG_ARM64_PTR_AUTH, since it currently only mentions userspace >>>> support, but now the option also enables KVM guest support. >>>> >>>> It's also worth mentioning that CONFIG_ARM64_VHE=y is required for guest >>>> support. >>> >>> Is it worth making this dependency explicit in Kconfig? >> Currently there is discrepancy that userspace supports ptrauth in both >> nVHE/VHE mode and KVM guest only in VHE mode. I suppose adding explicit >> dependency flag here makes both of them similar. > > Looking at the history, for SVE this Kconfig restriction has always been > present. Since ptrauth initially upstreamed without an equivalent > restriction in Kconfig, adding it now could be seen as a regression. ok it makes sense to keep it this way. > > So, maybe it's not worth it here. > > You could add a separate option, say > > config ARM64_PTR_AUTH_KVM > bool "Pointer authentication support for KVM guests" > default y > depends on ARM64_PTR_AUTH && ARM64_VHE && KVM > > ...but that may be overkill. I was thinking for adding some details for this in virtualization section in Documentation/arm64/pointer-authentication.txt along with brief comment in arch/arm64/Kconfig. Thanks, Amit D > > Cheers, > ---Dave >