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=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 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 E64D9C433E0 for ; Fri, 5 Mar 2021 18:19:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BEE8E650B7 for ; Fri, 5 Mar 2021 18:19:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229919AbhCESTZ (ORCPT ); Fri, 5 Mar 2021 13:19:25 -0500 Received: from mga09.intel.com ([134.134.136.24]:16642 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229526AbhCESTP (ORCPT ); Fri, 5 Mar 2021 13:19:15 -0500 IronPort-SDR: 4SXeAhiTGcU1b6hToXet6fDpC6kqxnnLXiQkr4Luw1SYwMEr0CfBdxrvYtKFSB8PTebX5IqKW2 Bil+uM1SCn2A== X-IronPort-AV: E=McAfee;i="6000,8403,9914"; a="187807333" X-IronPort-AV: E=Sophos;i="5.81,225,1610438400"; d="scan'208";a="187807333" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2021 10:19:14 -0800 IronPort-SDR: Yve4Xs/BQQO/dPrUERl1ezaSRoE42oOdpR/DR9drzbbAJMBbkvwbwxAPL/sU8t0amziAK3gbiO W9p6P5svTYjw== X-IronPort-AV: E=Sophos;i="5.81,225,1610438400"; d="scan'208";a="436593317" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.199.155]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2021 10:19:13 -0800 Date: Fri, 5 Mar 2021 10:20:48 -0800 From: Jacob Pan To: Jean-Philippe Brucker Cc: Tejun Heo , LKML , Joerg Roedel , Lu Baolu , David Woodhouse , iommu@lists.linux-foundation.org, cgroups@vger.kernel.org, Johannes Weiner , Jean-Philippe Brucker , Alex Williamson , Eric Auger , Jason Gunthorpe , Jonathan Corbet , Raj Ashok , "Tian, Kevin" , Yi Liu , Wu Hao , Dave Jiang , jacob.jun.pan@linux.intel.com Subject: Re: [RFC PATCH 15/18] cgroup: Introduce ioasids controller Message-ID: <20210305102048.7c274968@jacob-builder> In-Reply-To: References: <1614463286-97618-1-git-send-email-jacob.jun.pan@linux.intel.com> <1614463286-97618-16-git-send-email-jacob.jun.pan@linux.intel.com> <20210303131726.7a8cb169@jacob-builder> <20210303160205.151d114e@jacob-builder> <20210304094603.4ab6c1c4@jacob-builder> Organization: OTC X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jean-Philippe, On Fri, 5 Mar 2021 09:30:49 +0100, Jean-Philippe Brucker wrote: > On Thu, Mar 04, 2021 at 09:46:03AM -0800, Jacob Pan wrote: > > Hi Jean-Philippe, > > > > On Thu, 4 Mar 2021 10:49:37 +0100, Jean-Philippe Brucker > > wrote: > > > > > On Wed, Mar 03, 2021 at 04:02:05PM -0800, Jacob Pan wrote: > > > > Hi Jacob, > > > > > > > > On Wed, 3 Mar 2021 13:17:26 -0800, Jacob Pan > > > > wrote: > > > > > > > > > Hi Tejun, > > > > > > > > > > On Wed, 3 Mar 2021 10:44:28 -0500, Tejun Heo > > > > > wrote: > > > > > > On Sat, Feb 27, 2021 at 02:01:23PM -0800, Jacob Pan wrote: > > > > > > > IOASIDs are used to associate DMA requests with virtual > > > > > > > address spaces. They are a system-wide limited resource made > > > > > > > available to the userspace applications. Let it be VMs or > > > > > > > user-space device drivers. > > > > > > > > > > > > > > This RFC patch introduces a cgroup controller to address the > > > > > > > following problems: > > > > > > > 1. Some user applications exhaust all the available IOASIDs > > > > > > > thus depriving others of the same host. > > > > > > > 2. System admins need to provision VMs based on their needs > > > > > > > for IOASIDs, e.g. the number of VMs with assigned devices > > > > > > > that perform DMA requests with PASID. > > > > > > > > > > > > Please take a look at the proposed misc controller: > > > > > > > > > > > > http://lkml.kernel.org/r/20210302081705.1990283-2-vipinsh@google.com > > > > > > > > > > > > Would that fit your bill? > > > > > The interface definitely can be reused. But IOASID has a different > > > > > behavior in terms of migration and ownership checking. I guess > > > > > SEV key IDs are not tied to a process whereas IOASIDs are. > > > > > Perhaps this can be solved by adding > > > > > + .can_attach = ioasids_can_attach, > > > > > + .cancel_attach = ioasids_cancel_attach, > > > > > Let me give it a try and come back. > > > > > > > > > While I am trying to fit the IOASIDs cgroup in to the misc cgroup > > > > proposal. I'd like to have a direction check on whether this idea of > > > > using cgroup for IOASID/PASID resource management is viable. > > > > > > Yes, even for host SVA it would be good to have a cgroup. Currently > > > the number of shared address spaces is naturally limited by number of > > > processes, which can be controlled with rlimit and cgroup. But on Arm > > > the hardware limit on shared address spaces is 64k (number of ASIDs), > > > easily exhausted with the default PASID and PID limits. So a cgroup > > > for managing this resource is more than welcome. > > > > > > It looks like your current implementation is very dependent on > > > IOASID_SET_TYPE_MM? I'll need to do more reading about cgroup to see > > > how easily it can be adapted to host SVA which uses > > > IOASID_SET_TYPE_NULL. > > Right, I was assuming have three use cases of IOASIDs: > > 1. host supervisor SVA (not a concern, just one init_mm to bind) > > 2. host user SVA, either one IOASID per process or perhaps some private > > IOASID for private address space > > 3. VM use for guest SVA, each IOASID is bound to a guest process > > > > My current cgroup proposal applies to #3 with IOASID_SET_TYPE_MM, which > > is allocated by the new /dev/ioasid interface. > > > > For #2, I was thinking you can limit the host process via PIDs cgroup? > > i.e. limit fork. > > That works but isn't perfect, because the hardware resource of shared > address spaces can be much lower that PID limit - 16k ASIDs on Arm. To > allow an admin to fairly distribute that resource we could introduce > another cgroup just to limit the number of shared address spaces, but > limiting the number of IOASIDs does the trick. > make sense. it would be cleaner to have a single approach to limit IOASIDs (as Jason asked). > > So the host IOASIDs are currently allocated from the system pool > > with quota of chosen by iommu_sva_init() in my patch, 0 means unlimited > > use whatever is available. https://lkml.org/lkml/2021/2/28/18 > > Yes that's sensible, but it would be good to plan the cgroup user > interface to work for #2 as well, even if we don't implement it right > away. > will do it in the next version. > Thanks, > Jean Thanks, Jacob