From patchwork Wed Feb 26 07:06:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Wang X-Patchwork-Id: 1244724 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=DkkDlg6u; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 48S6M010Tdz9sPK for ; Wed, 26 Feb 2020 18:07:38 +1100 (AEDT) Received: from localhost ([::1]:38854 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6qn8-0007xW-26 for incoming@patchwork.ozlabs.org; Wed, 26 Feb 2020 02:07:34 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:54335) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6qmq-0007xD-BU for qemu-devel@nongnu.org; Wed, 26 Feb 2020 02:07:17 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j6qmo-0000G4-8P for qemu-devel@nongnu.org; Wed, 26 Feb 2020 02:07:15 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:30735 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 1j6qmo-0000EC-46 for qemu-devel@nongnu.org; Wed, 26 Feb 2020 02:07:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582700833; 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=jKQwo1nb44muwnghXEkj5MvoQoiMXJnQDobqHPh0c0c=; b=DkkDlg6uvRjEOPgThRecFL7VPpNiFQlJoMSi/+kM/Jzu+7jUtzQkAmb9kmO3ufvx2lMoAa +Ry6KA36AdzVXuAYqUd0um6oLEyLmm6fCE/Pbs2RWJve4g11r6yhS3f/dH2Q7Q0vbq4Hi0 fSljIfB3sc+YkcJF+NH2Z0kyEtK4K90= 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-191-22l3ufk7OW6EAvMisXEeyg-1; Wed, 26 Feb 2020 02:07:11 -0500 X-MC-Unique: 22l3ufk7OW6EAvMisXEeyg-1 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 C8BD5801E5C; Wed, 26 Feb 2020 07:07:10 +0000 (UTC) Received: from jason-ThinkPad-X1-Carbon-6th.redhat.com (ovpn-13-217.pek2.redhat.com [10.72.13.217]) by smtp.corp.redhat.com (Postfix) with ESMTP id C93A65C28C; Wed, 26 Feb 2020 07:06:57 +0000 (UTC) From: Jason Wang To: mst@redhat.com, qemu-devel@nongnu.org Subject: [PATCH] vhost: correctly turn on VIRTIO_F_IOMMU_PLATFORM Date: Wed, 26 Feb 2020 15:06:47 +0800 Message-Id: <20200226070647.8103-1-jasowang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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: pasic@linux.ibm.com, Jason Wang Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" 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") Signed-off-by: Jason Wang --- 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..6e12c3d2de 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_has_feature(dev->acked_features, 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 (dev->vdev->dma_as == &address_space_memory) { + 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");