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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 403DDC4360F for ; Wed, 3 Apr 2019 06:06:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0CC102084B for ; Wed, 3 Apr 2019 06:06:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727019AbfDCGGL (ORCPT ); Wed, 3 Apr 2019 02:06:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53128 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725879AbfDCGGL (ORCPT ); Wed, 3 Apr 2019 02:06:11 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5A6473082141; Wed, 3 Apr 2019 06:06:11 +0000 (UTC) Received: from xz-x1 (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2F2331018A16; Wed, 3 Apr 2019 06:06:00 +0000 (UTC) Date: Wed, 3 Apr 2019 14:05:58 +0800 From: Peter Xu To: Alex Williamson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, eric.auger@redhat.com, cohuck@redhat.com Subject: Re: [PATCH v2] vfio/type1: Limit DMA mappings per container Message-ID: <20190403060558.GL11008@xz-x1> References: <155422160029.16896.1992475589398080933.stgit@gimli.home> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <155422160029.16896.1992475589398080933.stgit@gimli.home> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Wed, 03 Apr 2019 06:06:11 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 02, 2019 at 10:15:38AM -0600, Alex Williamson wrote: > Memory backed DMA mappings are accounted against a user's locked > memory limit, including multiple mappings of the same memory. This > accounting bounds the number of such mappings that a user can create. > However, DMA mappings that are not backed by memory, such as DMA > mappings of device MMIO via mmaps, do not make use of page pinning > and therefore do not count against the user's locked memory limit. > These mappings still consume memory, but the memory is not well > associated to the process for the purpose of oom killing a task. > > To add bounding on this use case, we introduce a limit to the total > number of concurrent DMA mappings that a user is allowed to create. > This limit is exposed as a tunable module option where the default > value of 64K is expected to be well in excess of any reasonable use > case (a large virtual machine configuration would typically only make > use of tens of concurrent mappings). > > This fixes CVE-2019-3882. > > Signed-off-by: Alex Williamson Reviewed-by: Peter Xu Thanks, -- Peter Xu