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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 C27CDC433E0 for ; Wed, 24 Jun 2020 09:38:56 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 568DF20885 for ; Wed, 24 Jun 2020 09:38:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 568DF20885 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B79F54B14D; Wed, 24 Jun 2020 05:38:55 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bcEx4WJLR-Gl; Wed, 24 Jun 2020 05:38:54 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id AA5494B156; Wed, 24 Jun 2020 05:38:54 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9F20C4B14A for ; Wed, 24 Jun 2020 05:38:53 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id jyhZp7IWDDlX for ; Wed, 24 Jun 2020 05:38:52 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 4CC3F4B149 for ; Wed, 24 Jun 2020 05:38:52 -0400 (EDT) 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 AD8111FB; Wed, 24 Jun 2020 02:38:51 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 68A463F73C; Wed, 24 Jun 2020 02:38:50 -0700 (PDT) Date: Wed, 24 Jun 2020 10:38:48 +0100 From: Catalin Marinas To: Peter Maydell Subject: Re: [RFC PATCH 0/2] MTE support for KVM guest Message-ID: <20200624093846.GA11863@gaia> References: <20200617123844.29960-1-steven.price@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Cc: Marc Zyngier , lkml - Kernel Mailing List , Steven Price , kvmarm@lists.cs.columbia.edu, Thomas Gleixner , Will Deacon , Dave Martin , arm-mail-list X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Tue, Jun 23, 2020 at 07:05:07PM +0100, Peter Maydell wrote: > On Wed, 17 Jun 2020 at 13:39, Steven Price wrote: > > These patches add support to KVM to enable MTE within a guest. It is > > based on Catalin's v4 MTE user space series[1]. > > > > [1] http://lkml.kernel.org/r/20200515171612.1020-1-catalin.marinas%40arm.com > > > > Posting as an RFC as I'd like feedback on the approach taken. > > What's your plan for handling tags across VM migration? > Will the kernel expose the tag ram to userspace so we > can copy it from the source machine to the destination > at the same time as we copy the actual ram contents ? Qemu can map the guest memory with PROT_MTE and access the tags directly with LDG/STG instructions. Steven was actually asking in the cover letter whether we should require that the VMM maps the guest memory with PROT_MTE as a guarantee that it can access the guest tags. There is no architecturally visible tag ram (tag storage), that's a microarchitecture detail. -- Catalin _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 252E7C433DF for ; Wed, 24 Jun 2020 09:41:02 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 E0A9320720 for ; Wed, 24 Jun 2020 09:41:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="fFQOmX1J" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E0A9320720 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=DCCbXdtm7HKZInaO1JRxuZT97JS0HIS9qy3KvkDgMps=; b=fFQOmX1JZm06d+YDFyPRsf0iN pE070E+5ql7DwfdXNMRjdkXbDaYkx8dGzsettQNafKI9ugxbXKq6T8bFxjZO9ACmjofLoJ7HLez2e AlzgvPR9eTqXYVREUXPLoawX8SGD5sFLQdNAhAkuyIDLhtLeNIUBJZvo5rzkyVzg8fq2iu7qZXwJG RqxZPi2Iz3ApDCQwTpd7OBtAPLt42LsXSjJCVsLIdXOKI3PagtmwYxxGX/k+bFlcydUqY/pSyBM2i B31znO8Lc4gs0kkj75dObawtdFp8/uxFyl0nUQrI0uvwaYsltbwGTfbBWw+kzb0jHMAJ7cFf0A3s/ LWCnmBsRg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jo1rr-0001GV-LI; Wed, 24 Jun 2020 09:38:55 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jo1rp-0001Fn-AR for linux-arm-kernel@lists.infradead.org; Wed, 24 Jun 2020 09:38:54 +0000 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 AD8111FB; Wed, 24 Jun 2020 02:38:51 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 68A463F73C; Wed, 24 Jun 2020 02:38:50 -0700 (PDT) Date: Wed, 24 Jun 2020 10:38:48 +0100 From: Catalin Marinas To: Peter Maydell Subject: Re: [RFC PATCH 0/2] MTE support for KVM guest Message-ID: <20200624093846.GA11863@gaia> References: <20200617123844.29960-1-steven.price@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marc Zyngier , lkml - Kernel Mailing List , Steven Price , kvmarm@lists.cs.columbia.edu, Thomas Gleixner , Will Deacon , Dave Martin , arm-mail-list 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 Tue, Jun 23, 2020 at 07:05:07PM +0100, Peter Maydell wrote: > On Wed, 17 Jun 2020 at 13:39, Steven Price wrote: > > These patches add support to KVM to enable MTE within a guest. It is > > based on Catalin's v4 MTE user space series[1]. > > > > [1] http://lkml.kernel.org/r/20200515171612.1020-1-catalin.marinas%40arm.com > > > > Posting as an RFC as I'd like feedback on the approach taken. > > What's your plan for handling tags across VM migration? > Will the kernel expose the tag ram to userspace so we > can copy it from the source machine to the destination > at the same time as we copy the actual ram contents ? Qemu can map the guest memory with PROT_MTE and access the tags directly with LDG/STG instructions. Steven was actually asking in the cover letter whether we should require that the VMM maps the guest memory with PROT_MTE as a guarantee that it can access the guest tags. There is no architecturally visible tag ram (tag storage), that's a microarchitecture detail. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 E6F57C433E0 for ; Wed, 24 Jun 2020 09:38:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BEE0920885 for ; Wed, 24 Jun 2020 09:38:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389825AbgFXJiw (ORCPT ); Wed, 24 Jun 2020 05:38:52 -0400 Received: from foss.arm.com ([217.140.110.172]:53582 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388031AbgFXJiw (ORCPT ); Wed, 24 Jun 2020 05:38:52 -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 AD8111FB; Wed, 24 Jun 2020 02:38:51 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 68A463F73C; Wed, 24 Jun 2020 02:38:50 -0700 (PDT) Date: Wed, 24 Jun 2020 10:38:48 +0100 From: Catalin Marinas To: Peter Maydell Cc: Steven Price , Marc Zyngier , Will Deacon , Dave Martin , lkml - Kernel Mailing List , Thomas Gleixner , kvmarm@lists.cs.columbia.edu, arm-mail-list Subject: Re: [RFC PATCH 0/2] MTE support for KVM guest Message-ID: <20200624093846.GA11863@gaia> References: <20200617123844.29960-1-steven.price@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 23, 2020 at 07:05:07PM +0100, Peter Maydell wrote: > On Wed, 17 Jun 2020 at 13:39, Steven Price wrote: > > These patches add support to KVM to enable MTE within a guest. It is > > based on Catalin's v4 MTE user space series[1]. > > > > [1] http://lkml.kernel.org/r/20200515171612.1020-1-catalin.marinas%40arm.com > > > > Posting as an RFC as I'd like feedback on the approach taken. > > What's your plan for handling tags across VM migration? > Will the kernel expose the tag ram to userspace so we > can copy it from the source machine to the destination > at the same time as we copy the actual ram contents ? Qemu can map the guest memory with PROT_MTE and access the tags directly with LDG/STG instructions. Steven was actually asking in the cover letter whether we should require that the VMM maps the guest memory with PROT_MTE as a guarantee that it can access the guest tags. There is no architecturally visible tag ram (tag storage), that's a microarchitecture detail. -- Catalin