From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jason Wang <jasowang@redhat.com>,
Parav Pandit <parav@mellanox.com>,
Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
Dave Ertman <david.m.ertman@intel.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"nhorman@redhat.com" <nhorman@redhat.com>,
"sassmann@redhat.com" <sassmann@redhat.com>,
Kiran Patil <kiran.patil@intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
"Bie, Tiwei" <tiwei.bie@intel.com>
Subject: Re: [net-next v2 1/1] virtual-bus: Implementation of Virtual Bus
Date: Tue, 19 Nov 2019 19:16:21 -0500 [thread overview]
Message-ID: <20191119191053-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20191119231023.GN4991@ziepe.ca>
On Tue, Nov 19, 2019 at 07:10:23PM -0400, Jason Gunthorpe wrote:
> On Tue, Nov 19, 2019 at 04:33:40PM -0500, Michael S. Tsirkin wrote:
> > On Tue, Nov 19, 2019 at 03:15:47PM -0400, Jason Gunthorpe wrote:
> > > On Tue, Nov 19, 2019 at 01:58:42PM -0500, Michael S. Tsirkin wrote:
> > > > On Tue, Nov 19, 2019 at 12:46:32PM -0400, Jason Gunthorpe wrote:
> > > > > As always, this is all very hard to tell without actually seeing real
> > > > > accelerated drivers implement this.
> > > > >
> > > > > Your patch series might be a bit premature in this regard.
> > > >
> > > > Actually drivers implementing this have been posted, haven't they?
> > > > See e.g. https://lwn.net/Articles/804379/
> > >
> > > Is that a real driver? It looks like another example quality
> > > thing.
> > >
> > > For instance why do we need any of this if it has '#define
> > > IFCVF_MDEV_LIMIT 1' ?
> > >
> > > Surely for this HW just use vfio over the entire PCI function and be
> > > done with it?
> >
> > What this does is allow using it with unmodified virtio drivers
> > within guests. You won't get this with passthrough as it only
> > implements parts of virtio in hardware.
>
> I don't mean use vfio to perform passthrough, I mean to use vfio to
> implement the software parts in userspace while vfio to talk to the
> hardware.
You repeated vfio twice here, hard to decode what you meant actually.
> kernel -> vfio -> user space virtio driver -> qemu -> guest
Exactly what has been implemented for control path.
The interface between vfio and userspace is
based on virtio which is IMHO much better than
a vendor specific one. userspace stays vendor agnostic.
> Generally we don't want to see things in the kernel that can be done
> in userspace, and to me, at least for this driver, this looks
> completely solvable in userspace.
I don't think that extends as far as actively encouraging userspace
drivers poking at hardware in a vendor specific way. That has lots of
security and portability implications and isn't appropriate for
everyone. It is kernel's job to abstract hardware away and present
a unified interface as far as possible.
--
MST
next prev parent reply other threads:[~2019-11-20 0:16 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-15 22:33 [net-next v2 1/1] virtual-bus: Implementation of Virtual Bus Jeff Kirsher
2019-11-15 23:25 ` Parav Pandit
2019-11-19 3:58 ` Ertman, David M
2019-11-19 4:31 ` Parav Pandit
2019-11-19 4:39 ` Parav Pandit
2019-11-19 17:46 ` Ertman, David M
2019-11-19 18:39 ` Jason Gunthorpe
2019-11-19 17:44 ` Ertman, David M
2019-11-19 4:08 ` Jason Wang
2019-11-19 4:36 ` Parav Pandit
2019-11-19 6:51 ` Jason Wang
2019-11-19 7:13 ` Parav Pandit
2019-11-19 7:37 ` Jason Wang
2019-11-19 15:14 ` Parav Pandit
2019-11-20 3:15 ` Jason Wang
2019-11-20 3:38 ` Parav Pandit
2019-11-20 4:07 ` Jason Wang
2019-11-20 13:41 ` Jason Gunthorpe
2019-11-21 4:06 ` Jason Wang
2019-11-20 8:52 ` Michael S. Tsirkin
2019-11-20 12:03 ` Jiri Pirko
2019-11-19 16:46 ` Jason Gunthorpe
2019-11-19 18:58 ` Michael S. Tsirkin
2019-11-19 19:03 ` Jason Gunthorpe
2019-11-19 21:34 ` Michael S. Tsirkin
2019-11-19 19:15 ` Jason Gunthorpe
2019-11-19 21:33 ` Michael S. Tsirkin
2019-11-19 23:10 ` Jason Gunthorpe
2019-11-20 0:16 ` Michael S. Tsirkin [this message]
2019-11-20 1:46 ` Jason Gunthorpe
2019-11-20 3:59 ` Jason Wang
2019-11-20 5:34 ` Jason Wang
2019-11-20 13:38 ` Jason Gunthorpe
2019-11-20 14:15 ` Michael S. Tsirkin
2019-11-20 17:28 ` Alex Williamson
2019-11-20 18:11 ` Jason Gunthorpe
2019-11-20 22:07 ` Alex Williamson
2019-11-20 22:39 ` Parav Pandit
2019-11-21 8:17 ` Jason Wang
2019-11-21 3:03 ` Jason Gunthorpe
2019-11-21 4:24 ` Michael S. Tsirkin
2019-11-21 13:44 ` Jason Gunthorpe
2019-11-23 16:50 ` Michael S. Tsirkin
2019-11-21 7:21 ` Jason Wang
2019-11-21 14:17 ` Jason Gunthorpe
2019-11-22 8:45 ` Jason Wang
2019-11-22 18:02 ` Jason Gunthorpe
2019-11-23 4:39 ` Tiwei Bie
2019-11-23 23:09 ` Jason Gunthorpe
2019-11-24 11:00 ` Michael S. Tsirkin
2019-11-24 14:56 ` Tiwei Bie
2019-11-25 0:07 ` Jason Gunthorpe
2019-11-24 14:51 ` Tiwei Bie
2019-11-24 15:07 ` Michael S. Tsirkin
2019-11-25 0:09 ` Jason Gunthorpe
2019-11-25 12:59 ` Jason Wang
2019-11-23 16:48 ` Michael S. Tsirkin
2019-11-21 5:22 ` Jason Wang
2019-11-21 6:59 ` Jason Wang
2019-11-21 3:52 ` Jason Wang
2019-11-20 7:38 ` Michael S. Tsirkin
2019-11-20 13:03 ` Jason Gunthorpe
2019-11-20 13:43 ` Michael S. Tsirkin
2019-11-20 14:30 ` Jason Gunthorpe
2019-11-20 14:57 ` Michael S. Tsirkin
2019-11-20 16:45 ` Jason Gunthorpe
2019-11-20 22:05 ` Michael S. Tsirkin
2019-11-21 1:38 ` Jason Gunthorpe
2019-11-21 4:53 ` Jason Wang
2019-11-20 3:29 ` Jason Wang
2019-11-20 3:24 ` Jason Wang
2019-11-20 13:33 ` Jason Gunthorpe
2019-11-21 3:57 ` Jason Wang
2019-11-21 15:10 ` Martin Habets
2019-11-22 9:13 ` Jason Wang
2019-11-22 16:19 ` Parav Pandit
2019-11-26 12:26 ` Martin Habets
2019-11-27 10:58 ` Jason Wang
2019-11-27 11:03 ` Jason Wang
2019-11-15 23:42 ` Parav Pandit
2019-11-18 7:48 ` Greg KH
2019-11-18 22:57 ` Ertman, David M
2019-11-19 8:04 ` Jason Wang
2019-11-19 17:50 ` Ertman, David M
2019-11-18 7:49 ` Greg KH
2019-11-18 22:55 ` Ertman, David M
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