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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 49934C433E6 for ; Fri, 25 Dec 2020 07:04:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 193D823139 for ; Fri, 25 Dec 2020 07:04:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726322AbgLYHEE (ORCPT ); Fri, 25 Dec 2020 02:04:04 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:28803 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725787AbgLYHED (ORCPT ); Fri, 25 Dec 2020 02:04:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608879756; 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=s8DUQqG91PABTEtj2MPDM1N2c4jECR7hfbdn8/wSpCs=; b=F2PjQtDfbPF0awVjbt2dx5MN+Is71ZX6HCJeTCCwyxS6B6cMOGqGbvVquTYOoEn495fqpA OZJPb++6oZfrPX6aJCXjaFWEmrcV0afV4dB+NbPY1oDNXEmOiw4j99sAfbvpl/elGbbijl Yr+UnahC5Nf7f1GkslUo2fE0VXHaMQU= 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-424-VawPKdybPEmy16E223rQWQ-1; Fri, 25 Dec 2020 02:02:32 -0500 X-MC-Unique: VawPKdybPEmy16E223rQWQ-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 3E9581005D44; Fri, 25 Dec 2020 07:02:30 +0000 (UTC) Received: from [10.72.12.97] (ovpn-12-97.pek2.redhat.com [10.72.12.97]) by smtp.corp.redhat.com (Postfix) with ESMTP id AEA7560C5B; Fri, 25 Dec 2020 07:02:12 +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> From: Jason Wang Message-ID: Date: Fri, 25 Dec 2020 15:02:11 +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-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 2020/12/25 上午10:37, Yongji Xie wrote: > On Thu, Dec 24, 2020 at 3:37 PM Yongji Xie wrote: >> On Thu, Dec 24, 2020 at 10:41 AM Jason Wang wrote: >>> >>> On 2020/12/23 下午8:14, Yongji Xie wrote: >>>> On Wed, Dec 23, 2020 at 5:05 PM Jason Wang wrote: >>>>> On 2020/12/22 下午10:52, 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 process. >>>>>> >>>>>> This patch tries to make use of the vhost iotlb message to achieve >>>>>> 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/driver-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 device 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 different ways >>>>>> +depending on the vdpa bus to which it is attached. >>>>>> + >>>>>> +In virtio-vdpa case, VDUSE framework implements a MMU-based on-chip IOMMU >>>>>> driver which supports mapping the kernel dma buffer to a userspace 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 memory region >>>>>> +which will be shared to the VDUSE userspace processs via the file >>>>>> +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 on the userspace >>>>>> vDPA device fd are provided to support that: >>>>>> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_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 vduse_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 = vduse_dev_new_msg(dev, VDUSE_UPDATE_IOTLB); >>>>>> + msg->req.size = sizeof(struct vduse_iotlb); >>>>>> + msg->req.iotlb.offset = offset; >>>>>> + msg->req.iotlb.iova = iova; >>>>>> + msg->req.iotlb.size = size; >>>>>> + msg->req.iotlb.perm = perm; >>>>>> + msg->req.iotlb.fd = -1; >>>>>> + msg->iotlb_file = get_file(file); >>>>>> + >>>>>> + ret = vduse_dev_msg_sync(dev, msg); >>>>> My feeling is that we should provide consistent API for the userspace >>>>> device to use. >>>>> >>>>> E.g we'd better carry the IOTLB message for both virtio/vhost drivers. >>>>> >>>>> It looks to me for virtio drivers we can still use UPDAT_IOTLB message >>>>> 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 have >>> on-chip IOMMU e.g mlx5e and vdpa simlator), then we can introduce ioctl >>> 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? Or >> how about trigger it when userspace call mmap() on the device fd? >> > Oh sorry, looks like mmap() needs to be called in IOTLB UPDATE message > handler. Is it possible for the vdpa device to know which vdpa bus it > is attached to? We'd better not. It's kind of layer violation. Thanks > So that we can generate this message during probing. > Otherwise, we don't know whether the iova domain of MMU-based IOMMU is > needed. > > Thanks, > Yongji >