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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9034AC4332F for ; Fri, 4 Nov 2022 16:24:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4dBs5ePJ/iXMesF7Gjjj4YPuweHs70oG81Ro5h2tB0w=; b=MEh5bw/DZqvg0v JMW7LnBJUQ9ENoOpPx4ocLhMdlfRc8NhO/4j0+TrbFYDZwjq3w25mquEputTS+l4yX9N/M0MmXs7c 3zQ1VZTw8VqEdwYxCU8kJp/iPKuyIvu6xxEUW94hzOCpOC9/LkDe30mhO/lS5UrldazIUAfe9ekQ4 Yj19bAh/ZQBJPOZci1WbPV5rk6++ZYst8XBdwaPmSNE+4NixLxKMs9Lt/RQcq96aEsDCCxHNo5HMo +sPObPc0XAoqgWna5o55B8X9+4kuKlAunkjM0RxYBXaweZpbAzio8Kjk6Urf7u6slajCYFPEpvUuo UvdQB7hVnGBw7ElhTXQw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqzTV-004QKx-Ri; Fri, 04 Nov 2022 16:23:21 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqzTS-004QJj-HN for linux-arm-kernel@lists.infradead.org; Fri, 04 Nov 2022 16:23:20 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id CB43562291; Fri, 4 Nov 2022 16:23:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3561EC433C1; Fri, 4 Nov 2022 16:23:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667578997; bh=HnxmngU1KVgtQich1qdF/BW2KoU4yJ06AkHQpEggdoI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VqKSKrPpGIxkkS/qlbigYagJv0Aap3LqKf6eUZYOb++53kHk73IymIYEDKeogQiKT LPcRyEKB+eihiNTJfgEVkJNta1r79sNVEKsi5S9JTL5OS3PFXx+myLOHphBCKZTrLM h4JPNEv5MhMTFQN8/Tp+ZgbbqqlaOka36qKtTVpaf0SLCA0+vVct5sgvOdNAgNB0Qo lSGQ8ljDAVC7Qkwr1L2BYA0Yjl3bMY4gPLuN0F2gq0zBZGrPnY+hVLg8McmMDWAFGE De5RzNbbfXgDCpXHOJrh2qah+Seg7BE9ilJC2u3WXAuQxjf3cfdvgu7NBdPUR0FgPX Lwl+z1/0FtSFg== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1oqzTO-003pOc-OU; Fri, 04 Nov 2022 16:23:14 +0000 Date: Fri, 04 Nov 2022 16:23:14 +0000 Message-ID: <86a656r8nh.wl-maz@kernel.org> From: Marc Zyngier To: Peter Collingbourne Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, Cornelia Huck , Catalin Marinas , Will Deacon , Evgenii Stepanov , kvm@vger.kernel.org, Steven Price , Vincenzo Frascino , linux-mm Subject: Re: [PATCH v5 0/8] KVM: arm64: permit MAP_SHARED mappings with MTE enabled In-Reply-To: <20221104011041.290951-1-pcc@google.com> References: <20221104011041.290951-1-pcc@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: pcc@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, cohuck@redhat.com, catalin.marinas@arm.com, will@kernel.org, eugenis@google.com, kvm@vger.kernel.org, steven.price@arm.com, vincenzo.frascino@arm.com, linux-mm@kvack.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221104_092318_690694_10E19F38 X-CRM114-Status: GOOD ( 34.26 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 04 Nov 2022 01:10:33 +0000, Peter Collingbourne wrote: > > Hi, > > This patch series allows VMMs to use shared mappings in MTE enabled > guests. The first five patches were taken from Catalin's tree [1] which > addressed some review feedback from when they were previously sent out > as v3 of this series. The first patch from Catalin's tree makes room > for an additional PG_arch_3 flag by making the newer PG_arch_* flags > arch-dependent. The next four patches are based on a series that > Catalin sent out prior to v3, whose cover letter [2] I quote from below: > > > This series aims to fix the races between initialising the tags on a > > page and setting the PG_mte_tagged flag. Currently the flag is set > > either before or after that tag initialisation and this can lead to CoW > > copying stale tags. The first patch moves the flag setting after the > > tags have been initialised, solving the CoW issue. However, concurrent > > mprotect() on a shared mapping may (very rarely) lead to valid tags > > being zeroed. > > > > The second skips the sanitise_mte_tags() call in kvm_set_spte_gfn(), > > deferring it to user_mem_abort(). The outcome is that no > > sanitise_mte_tags() can be simplified to skip the pfn_to_online_page() > > check and only rely on VM_MTE_ALLOWED vma flag that can be checked in > > user_mem_abort(). > > > > The third and fourth patches use PG_arch_3 as a lock for page tagging, > > based on Peter Collingbourne's idea of a two-bit lock. > > > > I think the first patch can be queued but the rest needs some in depth > > review and test. With this series (if correct) we could allos MAP_SHARED > > on KVM guest memory but this is to be discussed separately as there are > > some KVM ABI implications. > > In this v5 I rebased Catalin's tree onto -next again. Please double check Please don't do use -next as a base. In-flight series should be based on a *stable* tag, either 6.0 or one of the early -RCs. If there is a known conflict with -next, do mention it in the cover letter and provide a resolution. > my rebase, which resolved the conflict with commit a8e5e5146ad0 ("arm64: > mte: Avoid setting PG_mte_tagged if no tags cleared or restored"). This commit seems part of -rc1, so I guess the patches directly apply on top of that tag? > I now have Reviewed-by for all patches except for the last one, which adds > the documentation. Thanks for the reviews so far, and please take a look! I'd really like the MM folks (list now cc'd) to look at the relevant patches (1 and 5) and ack them before I take this. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel