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=-8.8 required=3.0 tests=BAYES_00, 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 05189C4167B for ; Thu, 3 Dec 2020 16:10:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8286207A5 for ; Thu, 3 Dec 2020 16:10:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731204AbgLCQKh (ORCPT ); Thu, 3 Dec 2020 11:10:37 -0500 Received: from foss.arm.com ([217.140.110.172]:44216 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727395AbgLCQKg (ORCPT ); Thu, 3 Dec 2020 11:10:36 -0500 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 A8F8311D4; Thu, 3 Dec 2020 08:09:50 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.0.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8B4043F575; Thu, 3 Dec 2020 08:09:46 -0800 (PST) Date: Thu, 3 Dec 2020 16:09:43 +0000 From: Mark Rutland To: Steven Price Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Julien Thierry , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave Martin , Thomas Gleixner , qemu-devel@nongnu.org, Juan Quintela , "Dr. David Alan Gilbert" , Richard Henderson , Peter Maydell , Haibo Xu , Andrew Jones Subject: Re: [PATCH v6 0/2] MTE support for KVM guest Message-ID: <20201203160943.GG96754@C02TD0UTHF1T.local> References: <20201127152113.13099-1-steven.price@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201127152113.13099-1-steven.price@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 27, 2020 at 03:21:11PM +0000, Steven Price wrote: > It's been a week, and I think the comments on v5 made it clear that > enforcing PROT_MTE requirements on the VMM was probably the wrong > approach. So since I've got swap working correctly without that I > thought I'd post a v6 which hopefully addresses all the comments so far. > > This series adds support for Arm's Memory Tagging Extension (MTE) to > KVM, allowing KVM guests to make use of it. This builds on the existing > user space support already in v5.10-rc4, see [1] for an overview. > arch/arm64/include/asm/kvm_emulate.h | 3 +++ > arch/arm64/include/asm/kvm_host.h | 8 ++++++++ > arch/arm64/include/asm/pgtable.h | 2 +- > arch/arm64/include/asm/sysreg.h | 3 ++- > arch/arm64/kernel/mte.c | 18 +++++++++++++----- > arch/arm64/kvm/arm.c | 9 +++++++++ > arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 14 ++++++++++++++ > arch/arm64/kvm/mmu.c | 16 ++++++++++++++++ > arch/arm64/kvm/sys_regs.c | 20 +++++++++++++++----- > include/uapi/linux/kvm.h | 1 + > 10 files changed, 82 insertions(+), 12 deletions(-) I note that doesn't fixup arch/arm64/kvm/inject_fault.c, where in enter_exception64() we have: | // TODO: TCO (if/when ARMv8.5-MemTag is exposed to guests) ... and IIUC when MTE is present, TCO should be set when delivering an exception, so I believe that needs to be updated to set TCO. Given that MTE-capable HW does that unconditionally, this is going to be a mess for big.LITTLE. :/ Thanks, Mark.