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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 52820C433E0 for ; Wed, 17 Jun 2020 15:34:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2B0E2208B8 for ; Wed, 17 Jun 2020 15:34:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726958AbgFQPeV (ORCPT ); Wed, 17 Jun 2020 11:34:21 -0400 Received: from foss.arm.com ([217.140.110.172]:59784 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726878AbgFQPeU (ORCPT ); Wed, 17 Jun 2020 11:34:20 -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 55BD131B; Wed, 17 Jun 2020 08:34:20 -0700 (PDT) Received: from [192.168.1.84] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9374A3F73C; Wed, 17 Jun 2020 08:34:18 -0700 (PDT) Subject: Re: [RFC PATCH 2/2] arm64: kvm: Introduce MTE VCPU feature To: Catalin Marinas Cc: Marc Zyngier , Will Deacon , James Morse , Julien Thierry , Suzuki Poulose , "kvmarm@lists.cs.columbia.edu" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Dave P Martin , Mark Rutland , Thomas Gleixner References: <20200617123844.29960-1-steven.price@arm.com> <20200617123844.29960-3-steven.price@arm.com> <20200617143809.GF5388@gaia> From: Steven Price Message-ID: <9d4ef6cf-2333-83b8-c555-e70b99b95b28@arm.com> Date: Wed, 17 Jun 2020 16:34:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200617143809.GF5388@gaia> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/06/2020 15:38, Catalin Marinas wrote: > On Wed, Jun 17, 2020 at 01:38:44PM +0100, Steven Price wrote: >> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c >> index e3b9ee268823..040a7fffaa93 100644 >> --- a/virt/kvm/arm/mmu.c >> +++ b/virt/kvm/arm/mmu.c >> @@ -1783,6 +1783,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, >> vma_pagesize = PMD_SIZE; >> } >> >> + if (system_supports_mte() && kvm->arch.vcpu_has_mte) { >> + /* >> + * VM will be able to see the page's tags, so we must ensure >> + * they have been initialised. >> + */ >> + struct page *page = pfn_to_page(pfn); >> + >> + if (!test_and_set_bit(PG_mte_tagged, &page->flags)) >> + mte_clear_page_tags(page_address(page), page_size(page)); >> + } > > Are all the guest pages always mapped via a Stage 2 fault? It may be > better if we did that via kvm_set_spte_hva(). > I was under the impression that pages are always faulted into the stage 2, but I have to admit I'm not 100% sure about that. kvm_set_spte_hva() may be more appropriate, although on first look I don't understand how that function deals with huge pages. Is it actually called for normal mappings or only for changes due to the likes of KSM? Steve