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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 07F06C32771 for ; Thu, 9 Jan 2020 12:04:48 +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 C672C20661 for ; Thu, 9 Jan 2020 12:04:47 +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="J1I9j3GX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C672C20661 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]:59090 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ipWYQ-00050v-E5 for qemu-devel@archiver.kernel.org; Thu, 09 Jan 2020 07:04:46 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41859) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ipWWC-0002Hi-PV for qemu-devel@nongnu.org; Thu, 09 Jan 2020 07:02:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ipWWB-0001TX-Cs for qemu-devel@nongnu.org; Thu, 09 Jan 2020 07:02:28 -0500 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:36006 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ipWWB-0001QW-6L for qemu-devel@nongnu.org; Thu, 09 Jan 2020 07:02:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578571346; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=s/m/DPPmOtvxFMiS2XBx7cvLdh9f++FiEBXDX3B9vo4=; b=J1I9j3GX3oPrloPz5f3f4WmjqNW5m4G7R7Plpe8WA7ae6o2l0Lx/cgadWuhftqQkBKxFJt iU2XNY1EmIqy03KWGVGpr42qYePq6oVC3pF7noJa2nQxjm2QS72bdXXVo0WlN3YgZrd9u4 FUZI3BSaNH6+nNlqClVQsCivI/7iGYY= 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-225-XCXwtP68MPuwLj1iBAOAgw-1; Thu, 09 Jan 2020 07:02:23 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3F3BF107ACC9 for ; Thu, 9 Jan 2020 12:02:22 +0000 (UTC) Received: from work-vm (unknown [10.36.118.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CEC7D5C241; Thu, 9 Jan 2020 12:02:18 +0000 (UTC) Date: Thu, 9 Jan 2020 12:02:16 +0000 From: "Dr. David Alan Gilbert" To: Jason Wang Subject: Re: [PATCH 0/2] exclude hyperv synic sections from vhost Message-ID: <20200109120216.GA6795@work-vm> References: <20200108135353.75471-1-dgilbert@redhat.com> <53359208-3cd9-b0b6-f424-a5135e770fca@redhat.com> MIME-Version: 1.0 In-Reply-To: <53359208-3cd9-b0b6-f424-a5135e770fca@redhat.com> User-Agent: Mutt/1.13.0 (2019-11-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-MC-Unique: XCXwtP68MPuwLj1iBAOAgw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: vkuznets@redhat.com, qemu-devel@nongnu.org, mst@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Jason Wang (jasowang@redhat.com) wrote: >=20 > On 2020/1/8 =E4=B8=8B=E5=8D=889:53, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > >=20 > > Hyperv's synic (that we emulate) is a feature that allows the guest > > to place some magic (4k) pages of RAM anywhere it likes in GPA. > > This confuses vhost's RAM section merging when these pages > > land over the top of hugepages. >=20 >=20 > Hi David: >=20 > A silly question, is this because the alignment when adding sections? If > yes, what's the reason for doing alignment which is not a must for vhost > memory table. Page alignment is a bit odd with vhost-user - it ends up having to mmap each of the sections itself; and still has to map them as hugepages to be able to mmap - in the old world you could sometimes have the daemon mmaping the same chunk of memory twice into the vhost-user process; without the aggregation you'd get a hugepage mapping for the 0-2MB chunk for the 0-512K mapping, and then maybe another 0-2MB chunk for some of the other parts over 512K. With postcopy we can't have the multiple mappings of the same part of guest memory; we need to have one mapping for userfault. Also, given the 16 separate synic regions, you'd probably end up having a lot of wasted vhost-sections. Dave > Thanks >=20 >=20 > >=20 > > Since they're not normal RAM, and they shouldn't have vhost DMAing > > into them, exclude them from the vhost set. > >=20 > > I do that by marking them as device-ram and then excluding device-ram > > from vhost. > >=20 > > bz: https://bugzilla.redhat.com/show_bug.cgi?id=3D1779041 > >=20 > > Dr. David Alan Gilbert (2): > > vhost: Don't pass ram device sections > > hyperv/synic: Allocate as ram_device > >=20 > > hw/hyperv/hyperv.c | 14 ++++++++------ > > hw/virtio/vhost.c | 1 + > > 2 files changed, 9 insertions(+), 6 deletions(-) > >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK