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=-3.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 BB185C433E0 for ; Wed, 3 Jun 2020 13:54:48 +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 8649C206A2 for ; Wed, 3 Jun 2020 13:54:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hCF0BO14" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8649C206A2 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]:58248 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jgTqx-0003i1-Mk for qemu-devel@archiver.kernel.org; Wed, 03 Jun 2020 09:54:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56212) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jgTpZ-0002Mr-GC for qemu-devel@nongnu.org; Wed, 03 Jun 2020 09:53:21 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:52735 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jgTpY-0003nI-Cf for qemu-devel@nongnu.org; Wed, 03 Jun 2020 09:53:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591192398; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KSmhvyrUNPITZR71X8uXr+/WNZ47on5QwI4jFHkGKKM=; b=hCF0BO14eQuVO5UYKjZMkuYgvSBPQKZDffV952VKEQQsunkvP8adWKQMPNAdp60sqc33Pn 0N4CjigJFlEl04a5MjH9Nmf6ykztKu8v/peFrD3P2FBLH6vVsz6xF9IS+kcTfiqA71rF2X cXN011g8ki66OS5UiwQbxqJiVoLqopk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-82-AOecchZoO5K6dcDyYVZX9A-1; Wed, 03 Jun 2020 09:53:14 -0400 X-MC-Unique: AOecchZoO5K6dcDyYVZX9A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3AA5756B33; Wed, 3 Jun 2020 13:53:13 +0000 (UTC) Received: from linux.fritz.box (ovpn-112-187.ams2.redhat.com [10.36.112.187]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3B0487B5E1; Wed, 3 Jun 2020 13:53:09 +0000 (UTC) Date: Wed, 3 Jun 2020 15:53:07 +0200 From: Kevin Wolf To: Pavel Dovgalyuk Subject: Re: [PATCH v4] icount: make dma reads deterministic Message-ID: <20200603135307.GD5127@linux.fritz.box> References: <159117972206.12193.12939621311413561779.stgit@pasha-ThinkPad-X280> MIME-Version: 1.0 In-Reply-To: <159117972206.12193.12939621311413561779.stgit@pasha-ThinkPad-X280> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/03 01:04:34 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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: vsementsov@virtuozzo.com, qemu-devel@nongnu.org, mreitz@redhat.com, dovgaluk@ispras.ru, pavel.dovgaluk@ispras.ru, jsnow@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 03.06.2020 um 12:22 hat Pavel Dovgalyuk geschrieben: > From: Pavel Dovgalyuk > > Windows guest sometimes makes DMA requests with overlapping > target addresses. This leads to the following structure of iov for > the block driver: > > addr size1 > addr size2 > addr size3 > > It means that three adjacent disk blocks should be read into the same > memory buffer. Windows does not expects anything from these bytes > (should it be data from the first block, or the last one, or some mix), > but uses them somehow. It leads to non-determinism of the guest execution, > because block driver does not preserve any order of reading. > > This situation was discusses in the mailing list at least twice: > https://lists.gnu.org/archive/html/qemu-devel/2010-09/msg01996.html > https://lists.gnu.org/archive/html/qemu-devel/2020-02/msg05185.html > > This patch makes such disk reads deterministic in icount mode. > It splits the whole request into several parts. Parts may overlap, > but SGs inside one part do not overlap. > Parts that are processed later overwrite the prior ones in case > of overlapping. > > Examples for different SG part sequences: > > 1) > A1 1000 > A2 1000 > A1 1000 > A3 1000 > -> > One request is split into two. > A1 1000 > A2 1000 > -- > A1 1000 > A3 1000 > > 2) > A1 800 > A2 1000 > A1 1000 > -> > A1 800 > A2 1000 > -- > A1 1000 > > Signed-off-by: Pavel Dovgalyuk Thanks, applied to the block branch. Kevin