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=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 D56D6C4BA0B for ; Wed, 26 Feb 2020 09:54:21 +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 A13E42467B for ; Wed, 26 Feb 2020 09:54:21 +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="Wvuxt5h/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A13E42467B 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]:41436 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6tOW-0008Nr-ON for qemu-devel@archiver.kernel.org; Wed, 26 Feb 2020 04:54:20 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:32834) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6tNw-0007rI-CK for qemu-devel@nongnu.org; Wed, 26 Feb 2020 04:53:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j6tNv-0000Pr-9M for qemu-devel@nongnu.org; Wed, 26 Feb 2020 04:53:44 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:45198 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 1j6tNv-0000Mu-5F for qemu-devel@nongnu.org; Wed, 26 Feb 2020 04:53:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582710822; 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=ao2aSRHWfywR/cBul0O8Tym+Bi61eo+4TSSTHa1bOj0=; b=Wvuxt5h/hGMQP6PzPFsSISsHe8rwsouu5nRRvhdzmtbvvo6k4VhUg2xoXFruxm9ML8OBqz AOTNS7hCT8KcARkXHXDimEu4u/6LDyLJI9BS5E0+U1N1ae+itjiGR5LqWU3GEaxwrOWCjG qWC+MljsseBZSq/massZsutDmQ8RiuQ= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-364-righ6pfxNVCxie-T2IdG2g-1; Wed, 26 Feb 2020 04:53:38 -0500 X-MC-Unique: righ6pfxNVCxie-T2IdG2g-1 Received: by mail-qk1-f198.google.com with SMTP id a10so3414036qkg.11 for ; Wed, 26 Feb 2020 01:53:38 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Nb7JWOdVKx5PXc7GxFD9jzC/TqFyeZh7wn6KaCuQ1G8=; b=BMJdgKKh4JtaouzF+U7XLU6O2Ktd9mxABnC6rbfdut/vkkPSWxDdtLeqoO6jhtWmdA VpNEBQ7vIQ3mI00ZWU6HtCw2ErDBTN4jjiP0yca+PH54Hr4Cd42HL8XQsWttceVGamMA 6CPfRBxLxsfreuUF5/XjWUD46Ex1qfLQWGvY0GgAtT9FYH068P2fifFeMBPcrQAinPD0 HNziAx49BnhPxOqU8tjlkT7ogA/uvk+/WjHtmej6hImjIA5yX//2UGe30cTE7BqF+lmz LHppovak98vVvZcVVttRxtoD3+4ZVTxdx52z3V9o3KmBFUmilFXCVKfpVVX/qawZpCcJ iuhA== X-Gm-Message-State: APjAAAXV4U3c8LhQ5TUkzhwfkCcMW6FLr5rfhM8mfSuQOsNdL1fI+T22 jKBGRByAbGGoV63rUC91Rh5ba1dTdErYX6MTMv0yDb3u7EY43pvn4sZhRwtp9iu7CszAWR0q6K7 7z2h/FCiYOvrjF9I= X-Received: by 2002:ac8:60cf:: with SMTP id i15mr3807792qtm.6.1582710817994; Wed, 26 Feb 2020 01:53:37 -0800 (PST) X-Google-Smtp-Source: APXvYqw4//I2EUjuqlPAXh+8gx6zr3L632bD8wWLrHqLvccadWrQNY9/iG5Ko3PIrYRktx7UKS96LQ== X-Received: by 2002:ac8:60cf:: with SMTP id i15mr3807775qtm.6.1582710817717; Wed, 26 Feb 2020 01:53:37 -0800 (PST) Received: from redhat.com (bzq-79-178-2-214.red.bezeqint.net. [79.178.2.214]) by smtp.gmail.com with ESMTPSA id a14sm864135qkk.73.2020.02.26.01.53.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Feb 2020 01:53:36 -0800 (PST) Date: Wed, 26 Feb 2020 04:53:33 -0500 From: "Michael S. Tsirkin" To: Jason Wang Subject: Re: [PATCH V2] vhost: correctly turn on VIRTIO_F_IOMMU_PLATFORM Message-ID: <20200226045128-mutt-send-email-mst@kernel.org> References: <20200226094357.25061-1-jasowang@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200226094357.25061-1-jasowang@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.61 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, qemu-devel@nongnu.org, qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Feb 26, 2020 at 05:43:57PM +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. >=20 > Fixing this by check whether the device is backed by IOMMU and disable > device IOTLB. >=20 > Reported-by: Halil Pasic > Fixes: c471ad0e9bd46 ("vhost_net: device IOTLB support") Well it's just an optimization, isn't it? I don't think it's justified to push this to everyone using vhost with IOTLB, is it? If you disagree, could you comment a bit on which configurations where test= ed? > Cc: qemu-stable@nongnu.org > Signed-off-by: Jason Wang Halil could you test this pls? Does this help your performance issue? > --- > 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(-) >=20 > 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 *d= ev, > 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