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, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 57840C04AB6 for ; Tue, 28 May 2019 12:48:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 34FF820883 for ; Tue, 28 May 2019 12:48:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727555AbfE1MsX (ORCPT ); Tue, 28 May 2019 08:48:23 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:56858 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726973AbfE1MsW (ORCPT ); Tue, 28 May 2019 08:48:22 -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 2FDF580D; Tue, 28 May 2019 05:48:22 -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 A42393F5AF; Tue, 28 May 2019 05:48:19 -0700 (PDT) Subject: Re: [kvmtool PATCH v10 5/5] KVM: arm/arm64: Add a vcpu feature for pointer authentication To: Dave Martin 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 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> <20190528101128.GB28398@e103592.cambridge.arm.com> From: Amit Daniel Kachhap Message-ID: <53ecc253-e9e0-a6ca-2540-fa85bd26bfc1@arm.com> Date: Tue, 28 May 2019 18:18:16 +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: <20190528101128.GB28398@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 5/28/19 3:41 PM, Dave Martin wrote: > 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. I will clean up the print messages as you suggested and repost it shortly. Thanks, Amit Daniel > > Cheers > ---Dave >