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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 85047C04AB6 for ; Tue, 28 May 2019 10:11:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5BA9220883 for ; Tue, 28 May 2019 10:11:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726749AbfE1KLg (ORCPT ); Tue, 28 May 2019 06:11:36 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:54176 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726362AbfE1KLg (ORCPT ); Tue, 28 May 2019 06:11:36 -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 5E041341; Tue, 28 May 2019 03:11:35 -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 B45033F59C; Tue, 28 May 2019 03:11:33 -0700 (PDT) Date: Tue, 28 May 2019 11:11:31 +0100 From: Dave Martin To: Amit Daniel Kachhap Cc: Marc Zyngier , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Kristina Martsenko , Ramana Radhakrishnan , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: Re: [kvmtool PATCH v10 5/5] KVM: arm/arm64: Add a vcpu feature for pointer authentication Message-ID: <20190528101128.GB28398@e103592.cambridge.arm.com> References: <1555994558-26349-1-git-send-email-amit.kachhap@arm.com> <1555994558-26349-6-git-send-email-amit.kachhap@arm.com> <20190423154625.GP3567@e103592.cambridge.arm.com> <3b7bafc9-5d6a-7845-ef1f-577ea59000e2@arm.com> <20190424134120.GW3567@e103592.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190424134120.GW3567@e103592.cambridge.arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 24, 2019 at 02:41:21PM +0100, Dave Martin wrote: > On Wed, Apr 24, 2019 at 12:32:22PM +0530, Amit Daniel Kachhap wrote: > > Hi, > > > > On 4/23/19 9:16 PM, Dave Martin wrote: [...] > > >>diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c > > >>index 7780251..acd1d5f 100644 > > >>--- a/arm/kvm-cpu.c > > >>+++ b/arm/kvm-cpu.c > > >>@@ -68,6 +68,18 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id) > > >> vcpu_init.features[0] |= (1UL << KVM_ARM_VCPU_PSCI_0_2); > > >> } > > >>+ /* Check Pointer Authentication command line arguments. */ > > >>+ if (kvm->cfg.arch.enable_ptrauth && kvm->cfg.arch.disable_ptrauth) > > >>+ die("Both enable-ptrauth and disable-ptrauth option cannot be present"); > > > > > >Preferably, print the leading dashes, the same as the user would see > > >on the command line (e.g., --enable-ptrauth, --disable-ptrauth). > > > > > >For brevity, we could write something like: > > > > > > die("--enable-ptrauth conflicts with --disable-ptrauth"); [...] > > >>@@ -106,8 +118,12 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id) > > >> die("Unable to find matching target"); > > >> } > > >>- if (err || target->init(vcpu)) > > >>- die("Unable to initialise vcpu"); > > >>+ if (err || target->init(vcpu)) { > > >>+ if (kvm->cfg.arch.enable_ptrauth) > > >>+ die("Unable to initialise vcpu with pointer authentication feature"); > > > > > >We don't special-case this error message for any other feature yet: > > >there are a variety of reasons why we might have failed, so suggesting > > >that the failure is something to do with ptrauth may be misleading to > > >the user. > > > > > >If we want to be more informative, we could do something like the > > >following: > > > > > > bool supported; > > > > > > supported = kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_ADDRESS) && > > > kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_GENERIC); > > > > > > if (kvm->cfg.arch.enable_ptrauth && !supported) > > > die("--enable-ptrauth not supported on this host"); > > > > > > if (supported && !kvm->cfg.arch.disable_ptrauth) > > > vcpu_init.features[0] |= ARM_VCPU_PTRAUTH_FEATURE; > > > > > > /* ... */ > > > > > > if (err || target->init(vcpu)) > > > die("Unable to initialise vcpu"); > > > > > >We don't do this for any other feature today, but since it helps the > > >user to understand what went wrong it's probably a good idea. > > Yes this is more clear. As Mark has picked the core guest ptrauth patches. I > > will post this changes as standalone. > > Sounds good. (I also need to do that separately for SVE...) Were you planning to repost this? Alternatively, I can fix up the diagnostic messages discussed here and post it together with the SVE support. I'll do that locally for now, but let me know what you plan to do. I'd like to get the SVE support posted soon so that people can test it. Cheers ---Dave