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From: Yongji Xie <xieyongji@bytedance.com>
To: Parav Pandit <parav@nvidia.com>
Cc: Jason Wang <jasowang@redhat.com>,
	"virtualization@lists.linux-foundation.org" 
	<virtualization@lists.linux-foundation.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Eli Cohen <elic@nvidia.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [External] Re: [PATCH 0/7] Introduce vdpa management tool
Date: Tue, 1 Dec 2020 22:18:35 +0800
Message-ID: <CACycT3tTCmEzY37E5196Q2mqME2v+KpAp7Snn8wK4XtRKHEqEw@mail.gmail.com> (raw)
In-Reply-To: <DM6PR12MB4330173AF4BA08FE12F68B5BDCF40@DM6PR12MB4330.namprd12.prod.outlook.com>

On Tue, Dec 1, 2020 at 7:32 PM Parav Pandit <parav@nvidia.com> wrote:
>
>
>
> > From: Yongji Xie <xieyongji@bytedance.com>
> > Sent: Tuesday, December 1, 2020 3:26 PM
> >
> > On Tue, Dec 1, 2020 at 2:25 PM Jason Wang <jasowang@redhat.com> wrote:
> > >
> > >
> > > On 2020/11/30 下午3:07, Yongji Xie wrote:
> > > >>> Thanks for adding me, Jason!
> > > >>>
> > > >>> Now I'm working on a v2 patchset for VDUSE (vDPA Device in
> > > >>> Userspace) [1]. This tool is very useful for the vduse device. So
> > > >>> I'm considering integrating this into my v2 patchset. But there is
> > > >>> one problem:
> > > >>>
> > > >>> In this tool, vdpa device config action and enable action are
> > > >>> combined into one netlink msg: VDPA_CMD_DEV_NEW. But in vduse
> > > >>> case, it needs to be splitted because a chardev should be created
> > > >>> and opened by a userspace process before we enable the vdpa device
> > > >>> (call vdpa_register_device()).
> > > >>>
> > > >>> So I'd like to know whether it's possible (or have some plans) to
> > > >>> add two new netlink msgs something like: VDPA_CMD_DEV_ENABLE
> > and
> > > >>> VDPA_CMD_DEV_DISABLE to make the config path more flexible.
> > > >>>
> > > >> Actually, we've discussed such intermediate step in some early
> > > >> discussion. It looks to me VDUSE could be one of the users of this.
> > > >>
> > > >> Or I wonder whether we can switch to use anonymous inode(fd) for
> > > >> VDUSE then fetching it via an VDUSE_GET_DEVICE_FD ioctl?
> > > >>
> > > > Yes, we can. Actually the current implementation in VDUSE is like
> > > > this.  But seems like this is still a intermediate step. The fd
> > > > should be binded to a name or something else which need to be
> > > > configured before.
> > >
> > >
> > > The name could be specified via the netlink. It looks to me the real
> > > issue is that until the device is connected with a userspace, it can't
> > > be used. So we also need to fail the enabling if it doesn't opened.
> > >
> >
> > Yes, that's true. So you mean we can firstly try to fetch the fd binded to a
> > name/vduse_id via an VDUSE_GET_DEVICE_FD, then use the
> > name/vduse_id as a attribute to create vdpa device? It looks fine to me.
>
> I probably do not well understand. I tried reading patch [1] and few things do not look correct as below.
> Creating the vdpa device on the bus device and destroying the device from the workqueue seems unnecessary and racy.
>
> It seems vduse driver needs
> This is something should be done as part of the vdpa dev add command, instead of connecting two sides separately and ensuring race free access to it.
>
> So VDUSE_DEV_START and VDUSE_DEV_STOP should possibly be avoided.
>

Yes, we can avoid these two ioctls with the help of the management tool.

> $ vdpa dev add parentdev vduse_mgmtdev type net name foo2
>
> When above command is executed it creates necessary vdpa device foo2 on the bus.
> When user binds foo2 device with the vduse driver, in the probe(), it creates respective char device to access it from user space.

But vduse driver is not a vdpa bus driver. It works like vdpasim
driver, but offloads the data plane and control plane to a user space
process.

Thanks,
Yongji

  reply index

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12  6:39 Parav Pandit
2020-11-12  6:39 ` [PATCH 1/7] vdpa: Add missing comment for virtqueue count Parav Pandit
2020-11-12  6:40 ` [PATCH 2/7] vdpa: Use simpler version of ida allocation Parav Pandit
2020-11-12  6:40 ` [PATCH 3/7] vdpa: Extend routine to accept vdpa device name Parav Pandit
2020-11-12  6:40 ` [PATCH 4/7] vdpa: Define vdpa parent device, ops and a netlink interface Parav Pandit
2020-11-12  6:40 ` [PATCH 5/7] vdpa: Enable a user to add and delete a vdpa device Parav Pandit
2020-11-12  6:40 ` [PATCH 6/7] vdpa: Enable user to query vdpa device info Parav Pandit
2020-11-12  6:40 ` [PATCH 7/7] vdpa/vdpa_sim: Enable user to create vdpasim net devices Parav Pandit
2020-11-16  9:41 ` [PATCH 0/7] Introduce vdpa management tool Stefan Hajnoczi
2020-11-17 19:41   ` Parav Pandit
2020-11-16 22:23 ` Jakub Kicinski
2020-11-17 19:51   ` Parav Pandit
2020-12-16  9:13     ` Michael S. Tsirkin
     [not found]       ` <20201216080610.08541f44@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
2020-12-16 16:54         ` Parav Pandit
2020-12-16 19:57           ` Michael S. Tsirkin
2020-12-17 12:13             ` Parav Pandit
2020-11-27  3:53 ` Jason Wang
     [not found]   ` <CACycT3sYScObb9nN3g7L3cesjE7sCZWxZ5_5R1usGU9ePZEeqA@mail.gmail.com>
2020-11-30  3:36     ` [External] " Jason Wang
2020-11-30  7:07       ` Yongji Xie
2020-12-01  6:25         ` Jason Wang
2020-12-01  9:55           ` Yongji Xie
2020-12-01 11:32             ` Parav Pandit
2020-12-01 14:18               ` Yongji Xie [this message]
2020-12-01 15:58                 ` Parav Pandit
2020-12-02  3:29                   ` Yongji Xie
2020-12-02  4:53                     ` Parav Pandit
2020-12-02  5:51                       ` Jason Wang
2020-12-02  6:24                         ` Parav Pandit
2020-12-02  7:55                           ` Jason Wang
2020-12-02  9:27                         ` Yongji Xie
2020-12-02  9:21                       ` Yongji Xie
2020-12-02 11:13                         ` Parav Pandit
2020-12-02 13:18                           ` Yongji Xie
2020-12-02  5:48             ` Jason Wang
2020-12-08 22:47   ` David Ahern
2021-01-19  4:21     ` Parav Pandit
2020-12-16  9:16 ` Michael S. Tsirkin
2021-01-04  3:31 ` [PATCH linux-next v2 " Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 1/7] vdpa_sim_net: Make mac address array static Parav Pandit
2021-01-04  7:00     ` Jason Wang
2021-01-04  3:31   ` [PATCH linux-next v2 2/7] vdpa_sim_net: Add module param to disable default vdpa net device Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 3/7] vdpa: Extend routine to accept vdpa device name Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 4/7] vdpa: Define vdpa mgmt device, ops and a netlink interface Parav Pandit
2021-01-04  7:03     ` Jason Wang
2021-01-04  7:24       ` Parav Pandit
2021-01-05  4:10         ` Jason Wang
2021-01-05  6:33           ` Parav Pandit
2021-01-05  8:36             ` Jason Wang
2021-01-04  3:31   ` [PATCH linux-next v2 5/7] vdpa: Enable a user to add and delete a vdpa device Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 6/7] vdpa: Enable user to query vdpa device info Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 7/7] vdpa_sim_net: Add support for user supported devices Parav Pandit
2021-01-04  7:05     ` Jason Wang
2021-01-04  7:21       ` Parav Pandit
2021-01-05  4:06         ` Jason Wang
2021-01-05  6:22           ` Parav Pandit
2021-01-05 10:31 ` [PATCH linux-next v3 0/6] Introduce vdpa management tool Parav Pandit
2021-01-05 10:31   ` [PATCH linux-next v3 1/6] vdpa_sim_net: Make mac address array static Parav Pandit
2021-01-07 13:45     ` Stefano Garzarella
2021-01-05 10:31   ` [PATCH linux-next v3 2/6] vdpa: Extend routine to accept vdpa device name Parav Pandit
2021-01-05 10:32   ` [PATCH linux-next v3 3/6] vdpa: Define vdpa mgmt device, ops and a netlink interface Parav Pandit
2021-01-05 10:32   ` [PATCH linux-next v3 4/6] vdpa: Enable a user to add and delete a vdpa device Parav Pandit
2021-01-05 10:32   ` [PATCH linux-next v3 5/6] vdpa: Enable user to query vdpa device info Parav Pandit
2021-01-05 10:32   ` [PATCH linux-next v3 6/6] vdpa_sim_net: Add support for user supported devices Parav Pandit
2021-01-05 11:48     ` Michael S. Tsirkin
2021-01-05 12:02       ` Parav Pandit
2021-01-05 12:14         ` Michael S. Tsirkin
2021-01-05 12:30           ` Parav Pandit
2021-01-05 13:23             ` Michael S. Tsirkin
2021-01-07  3:48               ` Parav Pandit
2021-01-12  4:14                 ` Parav Pandit
2021-01-14  4:17                 ` Jason Wang
2021-01-14  7:58                   ` Parav Pandit
2021-01-15  5:38                     ` Jason Wang
2021-01-15  6:27                       ` Parav Pandit
2021-01-19 11:09                         ` Jason Wang
2021-01-20  3:21                           ` Parav Pandit
2021-01-20  3:46                             ` Parav Pandit
2021-01-18 18:03                       ` Parav Pandit
2021-01-20  7:53                         ` Michael S. Tsirkin

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