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=-17.7 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 13503C433DB for ; Mon, 28 Dec 2020 07:43:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 85947206F6 for ; Mon, 28 Dec 2020 07:43:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 85947206F6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 75CF06B00B6; Mon, 28 Dec 2020 02:43:26 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 70F806B0123; Mon, 28 Dec 2020 02:43:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5FB626B0128; Mon, 28 Dec 2020 02:43:26 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0080.hostedemail.com [216.40.44.80]) by kanga.kvack.org (Postfix) with ESMTP id 4A9976B00B6 for ; Mon, 28 Dec 2020 02:43:26 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 10551180AD802 for ; Mon, 28 Dec 2020 07:43:26 +0000 (UTC) X-FDA: 77641900812.04.rail52_240d65227492 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id E83AE8001D1D for ; Mon, 28 Dec 2020 07:43:25 +0000 (UTC) X-HE-Tag: rail52_240d65227492 X-Filterd-Recvd-Size: 9556 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf34.hostedemail.com (Postfix) with ESMTP for ; Mon, 28 Dec 2020 07:43:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1609141404; 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=DUqT+VEpmHhWLOUn9+3++KLEXvtfbXB6JHxQWM389zk=; b=Mf3skb855UcWMBxlbI+XUXdQD2yA8N+9ZQ1+DmnKdPP76L1sTCCcNBsApgSBWoJLGIRzZf on3fGEmmAlKG21ZeSrg04tyowkL6uvWi9JVUZ/zA5wrixAZ1epvLg8gIRj4K4FOUAhQP8J NL1ibJ/Nnuw8hh46d7jzPPJjL+2k7y0= 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-205-inycoFP9NTmopTKJEXh3dg-1; Mon, 28 Dec 2020 02:43:20 -0500 X-MC-Unique: inycoFP9NTmopTKJEXh3dg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 88979800D53; Mon, 28 Dec 2020 07:43:17 +0000 (UTC) Received: from [10.72.13.159] (ovpn-13-159.pek2.redhat.com [10.72.13.159]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4E52E60CC4; Mon, 28 Dec 2020 07:43:04 +0000 (UTC) Subject: Re: [RFC v2 09/13] vduse: Add support for processing vhost iotlb message To: Yongji Xie Cc: "Michael S. Tsirkin" , Stefan Hajnoczi , sgarzare@redhat.com, Parav Pandit , akpm@linux-foundation.org, Randy Dunlap , Matthew Wilcox , viro@zeniv.linux.org.uk, axboe@kernel.dk, bcrl@kvack.org, corbet@lwn.net, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20201222145221.711-1-xieyongji@bytedance.com> <20201222145221.711-10-xieyongji@bytedance.com> <6818a214-d587-4f0b-7de6-13c4e7e94ab6@redhat.com> <595fe7d6-7876-26e4-0b7c-1d63ca6d7a97@redhat.com> <0e6faf9c-117a-e23c-8d6d-488d0ec37412@redhat.com> From: Jason Wang Message-ID: <2b24398c-e6d9-14ec-2c0d-c303d528e377@redhat.com> Date: Mon, 28 Dec 2020 15:43:03 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2020/12/25 =E4=B8=8B=E5=8D=886:31, Yongji Xie wrote: > On Fri, Dec 25, 2020 at 2:58 PM Jason Wang wrote: >> >> On 2020/12/24 =E4=B8=8B=E5=8D=883:37, Yongji Xie wrote: >>> On Thu, Dec 24, 2020 at 10:41 AM Jason Wang wro= te: >>>> On 2020/12/23 =E4=B8=8B=E5=8D=888:14, Yongji Xie wrote: >>>>> On Wed, Dec 23, 2020 at 5:05 PM Jason Wang wr= ote: >>>>>> On 2020/12/22 =E4=B8=8B=E5=8D=8810:52, Xie Yongji wrote: >>>>>>> To support vhost-vdpa bus driver, we need a way to share the >>>>>>> vhost-vdpa backend process's memory with the userspace VDUSE proc= ess. >>>>>>> >>>>>>> This patch tries to make use of the vhost iotlb message to achiev= e >>>>>>> that. We will get the shm file from the iotlb message and pass it >>>>>>> to the userspace VDUSE process. >>>>>>> >>>>>>> Signed-off-by: Xie Yongji >>>>>>> --- >>>>>>> Documentation/driver-api/vduse.rst | 15 +++- >>>>>>> drivers/vdpa/vdpa_user/vduse_dev.c | 147 +++++++++++++++++++= +++++++++++++++++- >>>>>>> include/uapi/linux/vduse.h | 11 +++ >>>>>>> 3 files changed, 171 insertions(+), 2 deletions(-) >>>>>>> >>>>>>> diff --git a/Documentation/driver-api/vduse.rst b/Documentation/d= river-api/vduse.rst >>>>>>> index 623f7b040ccf..48e4b1ba353f 100644 >>>>>>> --- a/Documentation/driver-api/vduse.rst >>>>>>> +++ b/Documentation/driver-api/vduse.rst >>>>>>> @@ -46,13 +46,26 @@ The following types of messages are provided = by the VDUSE framework now: >>>>>>> >>>>>>> - VDUSE_GET_CONFIG: Read from device specific configuration = space >>>>>>> >>>>>>> +- VDUSE_UPDATE_IOTLB: Update the memory mapping in device IOTLB >>>>>>> + >>>>>>> +- VDUSE_INVALIDATE_IOTLB: Invalidate the memory mapping in devic= e IOTLB >>>>>>> + >>>>>>> Please see include/linux/vdpa.h for details. >>>>>>> >>>>>>> -In the data path, VDUSE framework implements a MMU-based on-chip= IOMMU >>>>>>> +The data path of userspace vDPA device is implemented in differe= nt ways >>>>>>> +depending on the vdpa bus to which it is attached. >>>>>>> + >>>>>>> +In virtio-vdpa case, VDUSE framework implements a MMU-based on-c= hip IOMMU >>>>>>> driver which supports mapping the kernel dma buffer to a use= rspace iova >>>>>>> region dynamically. The userspace iova region can be created= by passing >>>>>>> the userspace vDPA device fd to mmap(2). >>>>>>> >>>>>>> +In vhost-vdpa case, the dma buffer is reside in a userspace memo= ry region >>>>>>> +which will be shared to the VDUSE userspace processs via the fil= e >>>>>>> +descriptor in VDUSE_UPDATE_IOTLB message. And the corresponding = address >>>>>>> +mapping (IOVA of dma buffer <-> VA of the memory region) is also= included >>>>>>> +in this message. >>>>>>> + >>>>>>> Besides, the eventfd mechanism is used to trigger interrupt = callbacks and >>>>>>> receive virtqueue kicks in userspace. The following ioctls o= n the userspace >>>>>>> vDPA device fd are provided to support that: >>>>>>> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vd= pa_user/vduse_dev.c >>>>>>> index b974333ed4e9..d24aaacb6008 100644 >>>>>>> --- a/drivers/vdpa/vdpa_user/vduse_dev.c >>>>>>> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c >>>>>>> @@ -34,6 +34,7 @@ >>>>>>> >>>>>>> struct vduse_dev_msg { >>>>>>> struct vduse_dev_request req; >>>>>>> + struct file *iotlb_file; >>>>>>> struct vduse_dev_response resp; >>>>>>> struct list_head list; >>>>>>> wait_queue_head_t waitq; >>>>>>> @@ -325,12 +326,80 @@ static int vduse_dev_set_vq_state(struct vd= use_dev *dev, >>>>>>> return ret; >>>>>>> } >>>>>>> >>>>>>> +static int vduse_dev_update_iotlb(struct vduse_dev *dev, struct = file *file, >>>>>>> + u64 offset, u64 iova, u64 size, u8 = perm) >>>>>>> +{ >>>>>>> + struct vduse_dev_msg *msg; >>>>>>> + int ret; >>>>>>> + >>>>>>> + if (!size) >>>>>>> + return -EINVAL; >>>>>>> + >>>>>>> + msg =3D vduse_dev_new_msg(dev, VDUSE_UPDATE_IOTLB); >>>>>>> + msg->req.size =3D sizeof(struct vduse_iotlb); >>>>>>> + msg->req.iotlb.offset =3D offset; >>>>>>> + msg->req.iotlb.iova =3D iova; >>>>>>> + msg->req.iotlb.size =3D size; >>>>>>> + msg->req.iotlb.perm =3D perm; >>>>>>> + msg->req.iotlb.fd =3D -1; >>>>>>> + msg->iotlb_file =3D get_file(file); >>>>>>> + >>>>>>> + ret =3D vduse_dev_msg_sync(dev, msg); >>>>>> My feeling is that we should provide consistent API for the usersp= ace >>>>>> device to use. >>>>>> >>>>>> E.g we'd better carry the IOTLB message for both virtio/vhost driv= ers. >>>>>> >>>>>> It looks to me for virtio drivers we can still use UPDAT_IOTLB mes= sage >>>>>> by using VDUSE file as msg->iotlb_file here. >>>>>> >>>>> It's OK for me. One problem is when to transfer the UPDATE_IOTLB >>>>> message in virtio cases. >>>> Instead of generating IOTLB messages for userspace. >>>> >>>> How about record the mappings (which is a common case for device hav= e >>>> on-chip IOMMU e.g mlx5e and vdpa simlator), then we can introduce io= ctl >>>> for userspace to query? >>>> >>> If so, the IOTLB UPDATE is actually triggered by ioctl, but >>> IOTLB_INVALIDATE is triggered by the message. Is it a little odd? >> >> Good point. >> >> Some questions here: >> >> 1) Userspace think the IOTLB was flushed after IOTLB_INVALIDATE syscal= l >> is returned. But this patch doesn't have this guarantee. Can this lead >> some issues? > I'm not sure. But should it be guaranteed in VDUSE userspace? Just > like what vhost-user backend process does. I think so. This is because the userspace device needs a way to=20 synchronize invalidation with its datapath. Otherwise, guest may thing=20 the buffer is freed to be used by other parts but the it actually can be=20 used by the VDUSE device. The may cause security issues. > >> 2) I think after VDUSE userspace receives IOTLB_INVALIDATE, it needs t= o >> issue a munmap(). What if it doesn't do that? >> > Yes, the munmap() is needed. If it doesn't do that, VDUSE userspace > could still access the corresponding guest memory region. I see. So all the above two questions are because VHOST_IOTLB_INVALIDATE=20 is expected to be synchronous. This need to be solved by tweaking the=20 current VDUSE API or we can re-visit to go with descriptors relaying firs= t. Thanks > > Thanks, > Yongji >