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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 7D161C04AB5 for ; Mon, 3 Jun 2019 11:23:12 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 04CFE22CC0 for ; Mon, 3 Jun 2019 11:23:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 04CFE22CC0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 82C394A3B2; Mon, 3 Jun 2019 07:23:11 -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 w-PV7WzfQ+-K; Mon, 3 Jun 2019 07:23:10 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 244DB4A496; Mon, 3 Jun 2019 07:23:10 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 590084A3B2 for ; Mon, 3 Jun 2019 07:23:09 -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 pUfDUPXaaN-j for ; Mon, 3 Jun 2019 07:23:07 -0400 (EDT) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B7B954A319 for ; Mon, 3 Jun 2019 07:23:07 -0400 (EDT) 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 2B817A78; Mon, 3 Jun 2019 04:23:07 -0700 (PDT) Received: from e103592.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7E43B3F5AF; Mon, 3 Jun 2019 04:23:05 -0700 (PDT) Date: Mon, 3 Jun 2019 12:23:03 +0100 From: Dave Martin To: Andre Przywara Subject: Re: [PATCH kvmtool v3 5/9] KVM: arm/arm64: Add a vcpu feature for pointer authentication Message-ID: <20190603112302.GN28398@e103592.cambridge.arm.com> References: <1559229194-3036-1-git-send-email-Dave.Martin@arm.com> <1559229194-3036-6-git-send-email-Dave.Martin@arm.com> <20190531180416.3e87f5ad@donnerap.cambridge.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190531180416.3e87f5ad@donnerap.cambridge.arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Cc: Christoffer Dall , Marc Zyngier , Will Deacon , Kristina Martsenko , Zhang Lei , Amit Daniel Kachhap , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.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 Fri, May 31, 2019 at 06:04:16PM +0100, Andre Przywara wrote: > On Thu, 30 May 2019 16:13:10 +0100 > Dave Martin wrote: > > > From: Amit Daniel Kachhap > > > > This patch adds a runtime capabality for KVM tool to enable Arm64 8.3 > > Pointer Authentication in guest kernel. Two vcpu features > > KVM_ARM_VCPU_PTRAUTH_[ADDRESS/GENERIC] are supplied together to enable > > Pointer Authentication in KVM guest after checking the capability. > > > > Command line options --enable-ptrauth and --disable-ptrauth are added > > to use this feature. However, if those options are not provided then > > also this feature is enabled if host supports this capability. > > I don't really get the purpose of two options, I think that's quite > confusing. Should the first one either be dropped at all or called > something with "force"? > > I guess the idea is to fail if pointer auth isn't available, but the > option is supplied? > > Or maybe have one option with parameters? > --ptrauth[,=enable,=disable] So, I was following two principles here, either or both of which may be bogus: 1) There should be a way to determine whether KVM turns a given feature on or off (instead of magically defaulting to something). 2) To a first approaximation, kvmtool should allow each major KVM ABI feature to be exercised. 3) By default, kvmtool should offer the maximum feature set possible to the guest. (3) is well established, but (1) and (2) may be open to question? If we hold to both principles, it makes sense to have options functionally equivalent to what I suggested (where KVM provides the control in the first place), but there may be more convenient ways to respell the options. If we really can't decide, maybe it's better to drop the options altogether until we have a real use case. I've found the options very useful for testing and debugging on the SVE side, but I can't comment on ptrauth. Maybe someone else has a view? > > The macros defined in the headers are not in sync and should be replaced > > from the upstream. > > This is no longer true, I guess? Ah yes, that comment can go. Cheers ---Dave _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm