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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 7EA1CC4360C for ; Fri, 27 Sep 2019 12:18:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 59E21217D9 for ; Fri, 27 Sep 2019 12:18:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727559AbfI0MSB (ORCPT ); Fri, 27 Sep 2019 08:18:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49168 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725890AbfI0MSB (ORCPT ); Fri, 27 Sep 2019 08:18:01 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CC55C10DCC9D; Fri, 27 Sep 2019 12:18:00 +0000 (UTC) Received: from [10.72.12.24] (ovpn-12-24.pek2.redhat.com [10.72.12.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id E731E5D9C9; Fri, 27 Sep 2019 12:17:49 +0000 (UTC) Subject: Re: [PATCH] vhost: introduce mdev based hardware backend To: "Michael S. Tsirkin" Cc: Tiwei Bie , alex.williamson@redhat.com, maxime.coquelin@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, dan.daly@intel.com, cunming.liang@intel.com, zhihong.wang@intel.com, lingshan.zhu@intel.com References: <20190926045427.4973-1-tiwei.bie@intel.com> <20190926042156-mutt-send-email-mst@kernel.org> <20190926131439.GA11652@___> <8ab5a8d9-284d-bba5-803d-08523c0814e1@redhat.com> <20190927053935-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: Date: Fri, 27 Sep 2019 20:17:47 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190927053935-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.64]); Fri, 27 Sep 2019 12:18:00 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/9/27 下午5:41, Michael S. Tsirkin wrote: > On Fri, Sep 27, 2019 at 11:27:12AM +0800, Jason Wang wrote: >> On 2019/9/26 下午9:14, Tiwei Bie wrote: >>> On Thu, Sep 26, 2019 at 04:35:18AM -0400, Michael S. Tsirkin wrote: >>>> On Thu, Sep 26, 2019 at 12:54:27PM +0800, Tiwei Bie wrote: >>> [...] >>>>> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h >>>>> index 40d028eed645..5afbc2f08fa3 100644 >>>>> --- a/include/uapi/linux/vhost.h >>>>> +++ b/include/uapi/linux/vhost.h >>>>> @@ -116,4 +116,12 @@ >>>>> #define VHOST_VSOCK_SET_GUEST_CID _IOW(VHOST_VIRTIO, 0x60, __u64) >>>>> #define VHOST_VSOCK_SET_RUNNING _IOW(VHOST_VIRTIO, 0x61, int) >>>>> +/* VHOST_MDEV specific defines */ >>>>> + >>>>> +#define VHOST_MDEV_SET_STATE _IOW(VHOST_VIRTIO, 0x70, __u64) >>>>> + >>>>> +#define VHOST_MDEV_S_STOPPED 0 >>>>> +#define VHOST_MDEV_S_RUNNING 1 >>>>> +#define VHOST_MDEV_S_MAX 2 >>>>> + >>>>> #endif >>>> So assuming we have an underlying device that behaves like virtio: >>> I think they are really good questions/suggestions. Thanks! >>> >>>> 1. Should we use SET_STATUS maybe? >>> I like this idea. I will give it a try. >>> >>>> 2. Do we want a reset ioctl? >>> I think it is helpful. If we use SET_STATUS, maybe we >>> can use it to support the reset. >>> >>>> 3. Do we want ability to enable rings individually? >>> I will make it possible at least in the vhost layer. >> >> Note the API support e.g set_vq_ready(). > virtio spec calls this "enabled" so let's stick to that. Ok. > >>>> 4. Does device need to limit max ring size? >>>> 5. Does device need to limit max number of queues? >>> I think so. It's helpful to have ioctls to report the max >>> ring size and max number of queues. >> >> An issue is the max number of queues is done through a device specific way, >> usually device configuration space. This is supported by the transport API, >> but how to expose it to userspace may need more thought. >> >> Thanks > an ioctl for device config? But for v1 I'd be quite happy to just have > a minimal working device with 2 queues. I'm fully agree, and it will work as long as VIRTIO_NET_F_MQ and VIRTIO_NET_F_CTRL_VQ is not advertised by the mdev device. Thanks > >>> Thanks!