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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 28A7DC433B4 for ; Wed, 19 May 2021 13:53:28 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 DA81B611AE for ; Wed, 19 May 2021 13:53:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA81B611AE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:58392 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ljMdb-0001wM-1V for qemu-devel@archiver.kernel.org; Wed, 19 May 2021 09:53:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40548) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ljMDn-0004DT-Mz for qemu-devel@nongnu.org; Wed, 19 May 2021 09:26:47 -0400 Received: from foss.arm.com ([217.140.110.172]:59534) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ljMDl-0003V4-Cd for qemu-devel@nongnu.org; Wed, 19 May 2021 09:26:47 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 799E731B; Wed, 19 May 2021 06:26:43 -0700 (PDT) Received: from [192.168.1.179] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F1AF63F73B; Wed, 19 May 2021 06:26:40 -0700 (PDT) Subject: Re: [PATCH v12 6/8] arm64: kvm: Expose KVM_ARM_CAP_MTE To: Marc Zyngier References: <20210517123239.8025-1-steven.price@arm.com> <20210517123239.8025-7-steven.price@arm.com> <87tun1tg1l.wl-maz@kernel.org> From: Steven Price Message-ID: <4e1fc7b7-ea8c-a87c-9177-d9e03ff96cb8@arm.com> Date: Wed, 19 May 2021 14:26:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87tun1tg1l.wl-maz@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=217.140.110.172; envelope-from=steven.price@arm.com; helo=foss.arm.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Peter Maydell , "Dr. David Alan Gilbert" , Andrew Jones , Haibo Xu , Suzuki K Poulose , qemu-devel@nongnu.org, Catalin Marinas , Juan Quintela , Richard Henderson , linux-kernel@vger.kernel.org, Dave Martin , James Morse , linux-arm-kernel@lists.infradead.org, Thomas Gleixner , Will Deacon , kvmarm@lists.cs.columbia.edu, Julien Thierry Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 17/05/2021 18:40, Marc Zyngier wrote: > On Mon, 17 May 2021 13:32:37 +0100, > Steven Price wrote: >> >> It's now safe for the VMM to enable MTE in a guest, so expose the >> capability to user space. >> >> Signed-off-by: Steven Price >> --- >> arch/arm64/kvm/arm.c | 9 +++++++++ >> arch/arm64/kvm/sys_regs.c | 3 +++ >> 2 files changed, 12 insertions(+) >> >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index 1cb39c0803a4..e89a5e275e25 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -93,6 +93,12 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, >> r = 0; >> kvm->arch.return_nisv_io_abort_to_user = true; >> break; >> + case KVM_CAP_ARM_MTE: >> + if (!system_supports_mte() || kvm->created_vcpus) >> + return -EINVAL; >> + r = 0; >> + kvm->arch.mte_enabled = true; > > As far as I can tell from the architecture, this isn't valid for a > 32bit guest. Indeed, however the MTE flag is a property of the VM not of the vCPU. And, unless I'm mistaken, it's technically possible to create a VM where some CPUs are 32 bit and some 64 bit. Not that I can see much use of a configuration like that. Steve