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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 63EB9C31E49 for ; Wed, 19 Jun 2019 13:19:45 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 3D5ED2166E for ; Wed, 19 Jun 2019 13:19:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3D5ED2166E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38236 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdaV6-0001wZ-54 for qemu-devel@archiver.kernel.org; Wed, 19 Jun 2019 09:19:44 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39334) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdaU0-0001NZ-Ob for qemu-devel@nongnu.org; Wed, 19 Jun 2019 09:18:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hdaTz-0003gM-IP for qemu-devel@nongnu.org; Wed, 19 Jun 2019 09:18:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59400) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hdaTz-0003Eu-BY for qemu-devel@nongnu.org; Wed, 19 Jun 2019 09:18:35 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5195E330272; Wed, 19 Jun 2019 13:17:47 +0000 (UTC) Received: from [10.36.116.89] (ovpn-116-89.ams2.redhat.com [10.36.116.89]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 337A161090; Wed, 19 Jun 2019 13:17:42 +0000 (UTC) To: Yan Zhao , pbonzini@redhat.com References: <1560934185-14152-1-git-send-email-yan.y.zhao@intel.com> From: Auger Eric Message-ID: <39c4c32b-e34a-8d8f-abbc-ab346ec5bed7@redhat.com> Date: Wed, 19 Jun 2019 15:17:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <1560934185-14152-1-git-send-email-yan.y.zhao@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 19 Jun 2019 13:17:47 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH] memory: do not do out of bound notification X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, Peter Xu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Yan, [+ Peter] On 6/19/19 10:49 AM, Yan Zhao wrote: > even if an entry overlaps with notifier's range, should not map/unmap > out of bound part in the entry. I don't think the patch was based on the master as the trace at the very end if not part of the upstream code. > > This would cause problem in below case: > 1. initially there are two notifiers with ranges > 0-0xfedfffff, 0xfef00000-0xffffffffffffffff, > IOVAs from 0x3c000000 - 0x3c1fffff is in shadow page table. > > 2. in vfio, memory_region_register_iommu_notifier() is followed by > memory_region_iommu_replay(), which will first call address space unmap, > and walk and add back all entries in vtd shadow page table. e.g. > (1) for notifier 0-0xfedfffff, > IOVAs from 0 - 0xffffffff get unmapped, > and IOVAs from 0x3c000000 - 0x3c1fffff get mapped While the patch looks sensible, the issue is the notifier scope used in vtd_address_space_unmap is not a valid mask (ctpop64(size) != 1). Then the size is recomputed (either using n = 64 - clz64(size) for the 1st notifier or n = s->aw_bits for the 2d) and also the entry (especially for the 2d notifier where it becomes 0) to get a proper alignment. vtd_page_walk sends notifications per block or page (with valid addr_mask) so stays within the notifier. Modifying the entry->iova/addr_mask again in memory_region_notify_one leads to unaligned start address / addr_mask. I don't think we want that. Can't we modity the vtd_address_space_unmap() implementation to split the invalidation in smaller chunks instead? Thanks Eric > (2) for notifier 0xfef00000-0xffffffffffffffff > IOVAs from 0 - 0x7fffffffff get unmapped,> but IOVAs from 0x3c000000 - 0x3c1fffff cannot get mapped back. > > Signed-off-by: Yan Zhao > --- > memory.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/memory.c b/memory.c > index 07c8315..a6b9da6 100644 > --- a/memory.c > +++ b/memory.c > @@ -1948,6 +1948,14 @@ void memory_region_notify_one(IOMMUNotifier *notifier, > return; > } > > + if (entry->iova < notifier->start) { > + entry->iova = notifier->start; > + } > + > + if (entry->iova + entry->addr_mask > notifier->end) { > + entry->addr_mask = notifier->end - entry->iova;> + } > + > if (entry->perm & IOMMU_RW) { > printf("map %lx %lx\n", entry->iova, entry->iova + entry->addr_mask); > request_flags = IOMMU_NOTIFIER_MAP; >