From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 95EB4152A for ; Mon, 9 Jan 2017 05:51:19 +0100 (CET) Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DBF25C04B302; Mon, 9 Jan 2017 04:51:19 +0000 (UTC) Received: from [10.72.5.23] (vpn1-5-23.pek2.redhat.com [10.72.5.23]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v094pDBK007145 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 8 Jan 2017 23:51:16 -0500 To: "Tan, Jianfeng" , Yuanhan Liu References: <1480689075-66977-1-git-send-email-jianfeng.tan@intel.com> <1482477266-39199-1-git-send-email-jianfeng.tan@intel.com> <1482477266-39199-6-git-send-email-jianfeng.tan@intel.com> <20161226074437.GD19288@yliu-dev.sh.intel.com> <59e32f20-fe7a-20ad-1aa6-99fc90322a42@intel.com> Cc: dev@dpdk.org, ferruh.yigit@intel.com, cunming.liang@intel.com From: Jason Wang Message-ID: <9ecc9622-31e3-e8cc-41e6-4088ef7a7f5f@redhat.com> Date: Mon, 9 Jan 2017 12:51:11 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <59e32f20-fe7a-20ad-1aa6-99fc90322a42@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 09 Jan 2017 04:51:19 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH v2 5/7] net/virtio_user: add vhost kernel support X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Jan 2017 04:51:19 -0000 On 2017年01月04日 15:22, Tan, Jianfeng wrote: > > Sorry, I forget to reply this comment. > > On 12/26/2016 3:44 PM, Yuanhan Liu wrote: >> [...] >>> + >>> + /* Does not work when VIRTIO_F_IOMMU_PLATFORM now, why? */ >> Because this feature need the vhost IOTLB support from the device >> emulation. Patches for QEMU hasn't been merged yet, but it has been >> there for a while. > > Yes. And it's in need of help from QEMU. > >> >> Since we don't have the support yet, for sure it won't work. But >> I'm wondering why you have to disable it explicitly? > > Here we do not have QEMU. Frontend driver talks with vhost-net through > virtio_user_dev. And both ends claim to support > VIRTIO_F_IOMMU_PLATFORM. So this feature bit will be negotiated if we > don't explicitly disable it. In my previous test, it fails in > vhost_init_device_iotlb() of vhost kernel module. Interesting, vhost_init_device_iotlb() only fail when OOM. Do you meet it? > My guess is that, for this feature, without the help of QEMU, vhost > kernel module cannot work independently. Technically it can if your userspace supports device IOTLB APIs too. Or if you're using static mappings, and preset all mappings through VHOST_IOTLB_UPADATE to make sure no IOTLB misses. Thanks > > Thanks, > Jianfeng