From nobody Mon Feb 9 01:17:26 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1583123174; cv=none; d=zohomail.com; s=zohoarc; b=HJE6lxVqWLqV0NHJmWAwzxl2FsCCKIDNfLbIaTmCLv+zD6+iZLDw2yAjfZihedsHSfnhSzZKVgNu1CQ3IZWA7z6e7kjL/EBj4+gw2HGqOqW7nzpQfHbZmOt/5PQ7EkGPCjFQfgXSKByNUMOeZhaQlkNPQ3BQNUnUHhtbRpfl4cU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1583123174; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Sender:Subject:To; bh=jvWNRw+Ygvti/hp7R/fcBpiZ1L2h+OOs0iNXiyAsjTo=; b=AbljmBZT1JBsuucEm0DAHMriZHW2VK8xGQ+aJp+VQBJ9zVUdOllcWMc536eYJBu4Q8B/zKBaLcPFXAp+BzGQXZgtTO4m+5DCz/ZWSpE+hrgePKirhBXGG/rE84qVJfaTsK+qSGEoy6AyZnBtKA8tEwZOzXXufXQ4ZkOqpm6H+pc= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1583123174516464.38504034720165; Sun, 1 Mar 2020 20:26:14 -0800 (PST) Received: from localhost ([::1]:54674 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j8cei-0004fx-8o for importer@patchew.org; Sun, 01 Mar 2020 23:26:12 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:39281) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j8ce5-00049p-9D for qemu-devel@nongnu.org; Sun, 01 Mar 2020 23:25:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j8ce3-0004D1-9f for qemu-devel@nongnu.org; Sun, 01 Mar 2020 23:25:32 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:34024 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j8ce2-0004BT-V0 for qemu-devel@nongnu.org; Sun, 01 Mar 2020 23:25:31 -0500 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-241-Nur-VLLBPcevIN6aXo0R0g-1; Sun, 01 Mar 2020 23:25:26 -0500 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 255A5107ACCA; Mon, 2 Mar 2020 04:25:25 +0000 (UTC) Received: from jason-ThinkPad-X1-Carbon-6th.redhat.com (ovpn-13-131.pek2.redhat.com [10.72.13.131]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1769B19E9C; Mon, 2 Mar 2020 04:25:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583123130; 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; bh=jvWNRw+Ygvti/hp7R/fcBpiZ1L2h+OOs0iNXiyAsjTo=; b=NhZxCWk8bDOuKZzzinW+K1k9+WrJYbAg0TGDYWFjSGvNKGMeJRkooTSXWlx5B2/YLwmOmZ dEtaNKED0QOpF5hnbXsdCo7HXM1ZlLYHk9Rib68GMwA3o/lU/rbtYeIQTPUAdR5jzuKVW1 m+u/kZb75w+dCakQ4L/0/1MHrxxA9GA= X-MC-Unique: Nur-VLLBPcevIN6aXo0R0g-1 From: Jason Wang To: mst@redhat.com Subject: [PATCH V3] vhost: correctly turn on VIRTIO_F_IOMMU_PLATFORM Date: Mon, 2 Mar 2020 12:24:54 +0800 Message-Id: <20200302042454.24814-1-jasowang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: pasic@linux.ibm.com, thomas.lendacky@amd.com, Jason Wang , brijesh.singh@amd.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" 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 Tested-by: Halil Pasic Reviewed-by: Halil Pasic Signed-off-by: Jason Wang --- Changes from V2: - remove fixes tag - tested with guest kernel virtio drivers + vIOMMU 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 =3D dev->vdev; =20 - 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 !=3D &address_space_memory && + virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM); } =20 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 |=3D 0x1ULL << VHOST_F_LOG_ALL; } + if (!vhost_dev_has_iommu(dev)) { + features &=3D ~(0x1ULL << VIRTIO_F_IOMMU_PLATFORM); + } r =3D dev->vhost_ops->vhost_set_features(dev, features); if (r < 0) { VHOST_OPS_DEBUG("vhost_set_features failed"); --=20 2.19.1