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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 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 C44F7C4BA10 for ; Wed, 26 Feb 2020 13:29:31 +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 922D324683 for ; Wed, 26 Feb 2020 13:29:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 922D324683 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:44382 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6wkk-0004aE-Pt for qemu-devel@archiver.kernel.org; Wed, 26 Feb 2020 08:29:30 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:32992) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6wk3-00047q-9V for qemu-devel@nongnu.org; Wed, 26 Feb 2020 08:28:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j6wk2-0000fC-8p for qemu-devel@nongnu.org; Wed, 26 Feb 2020 08:28:47 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58970 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j6wk2-0000dV-3r for qemu-devel@nongnu.org; Wed, 26 Feb 2020 08:28:46 -0500 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 01QDKdtd100989 for ; Wed, 26 Feb 2020 08:28:45 -0500 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ydqfumqh0-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 26 Feb 2020 08:28:45 -0500 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 26 Feb 2020 13:28:42 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 01QDSfrf37552128 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Feb 2020 13:28:41 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2B372A405B; Wed, 26 Feb 2020 13:28:41 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 018A2A404D; Wed, 26 Feb 2020 13:28:41 +0000 (GMT) Received: from oc2783563651 (unknown [9.152.98.187]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 26 Feb 2020 13:28:40 +0000 (GMT) Date: Wed, 26 Feb 2020 14:28:39 +0100 From: Halil Pasic To: Jason Wang Subject: Re: [PATCH V2] vhost: correctly turn on VIRTIO_F_IOMMU_PLATFORM In-Reply-To: <20200226094357.25061-1-jasowang@redhat.com> References: <20200226094357.25061-1-jasowang@redhat.com> Organization: IBM X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 20022613-4275-0000-0000-000003A5A7C0 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20022613-4276-0000-0000-000038B9C028 Message-Id: <20200226142839.4263de9b.pasic@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.572 definitions=2020-02-26_04:2020-02-26, 2020-02-26 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 malwarescore=0 suspectscore=0 priorityscore=1501 phishscore=0 adultscore=0 bulkscore=0 impostorscore=0 lowpriorityscore=0 mlxlogscore=999 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002260099 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 148.163.158.5 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-stable@nongnu.org, qemu-devel@nongnu.org, mst@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 26 Feb 2020 17:43:57 +0800 Jason Wang wrote: > We turn on device IOTLB via VIRTIO_F_IOMMU_PLATFORM unconditionally on > platform without IOMMU support. This can lead unnecessary IOTLB > transactions which will damage the performance. > > Fixing this by check whether the device is backed by IOMMU and disable > device IOTLB. > > Reported-by: Halil Pasic > Fixes: c471ad0e9bd46 ("vhost_net: device IOTLB support") > Cc: qemu-stable@nongnu.org > Signed-off-by: Jason Wang Tested-by: Halil Pasic Reviewed-by: Halil Pasic Thank you very much for fixing this! BTW as I mentioned before it fixes vhost-vsock with iommu_platform=on as well. Regards, Halil > --- > Changes from V1: > - do not check acked_features > - reuse vhost_dev_has_iommu() > --- > hw/virtio/vhost.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > index 9edfadc81d..9182a00495 100644 > --- a/hw/virtio/vhost.c > +++ b/hw/virtio/vhost.c > @@ -290,7 +290,14 @@ static int vhost_dev_has_iommu(struct vhost_dev *dev) > { > VirtIODevice *vdev = dev->vdev; > > - return virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM); > + /* > + * For vhost, VIRTIO_F_IOMMU_PLATFORM means the backend support > + * incremental memory mapping API via IOTLB API. For platform that > + * does not have IOMMU, there's no need to enable this feature > + * which may cause unnecessary IOTLB miss/update trnasactions. > + */ > + return vdev->dma_as != &address_space_memory && > + virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM); > } > > static void *vhost_memory_map(struct vhost_dev *dev, hwaddr addr, > @@ -765,6 +772,9 @@ static int vhost_dev_set_features(struct vhost_dev *dev, > if (enable_log) { > features |= 0x1ULL << VHOST_F_LOG_ALL; > } > + if (!vhost_dev_has_iommu(dev)) { > + features &= ~(0x1ULL << VIRTIO_F_IOMMU_PLATFORM); > + } > r = dev->vhost_ops->vhost_set_features(dev, features); > if (r < 0) { > VHOST_OPS_DEBUG("vhost_set_features failed");