Netdev Archive on lore.kernel.org
 help / color / Atom feed
From: Parav Pandit <parav@mellanox.com>
To: Jason Gunthorpe <jgg@ziepe.ca>,
	Alex Williamson <alex.williamson@redhat.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>,
	Jiri Pirko <jiri@resnulli.us>, David M <david.m.ertman@intel.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Saeed Mahameed <saeedm@mellanox.com>,
	"kwankhede@nvidia.com" <kwankhede@nvidia.com>,
	"leon@kernel.org" <leon@kernel.org>,
	"cohuck@redhat.com" <cohuck@redhat.com>,
	Jiri Pirko <jiri@mellanox.com>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	Or Gerlitz <gerlitz.or@gmail.com>,
	"Jason Wang (jasowang@redhat.com)" <jasowang@redhat.com>
Subject: RE: [PATCH net-next 00/19] Mellanox, mlx5 sub function support
Date: Sat, 9 Nov 2019 00:45:04 +0000
Message-ID: <AM0PR05MB4866C174D5DAC301D97B8324D17A0@AM0PR05MB4866.eurprd05.prod.outlook.com> (raw)
In-Reply-To: <20191109001225.GA31761@ziepe.ca>

Hi Jason,

> -----Original Message-----
> From: Jason Gunthorpe <jgg@ziepe.ca>
> 
> On Fri, Nov 08, 2019 at 02:52:10PM -0700, Alex Williamson wrote:
> > > >
> > > > Unless there's some opposition, I'm intended to queue this for v5.5:
> > > >
> > > > https://www.spinics.net/lists/kvm/msg199613.html
> > > >
> > > > mdev has started out as tied to vfio, but at it's core, it's just
> > > > a device life cycle infrastructure with callbacks between bus
> > > > drivers and vendor devices.  If virtio is on the wrong path with
> > > > the above series, please speak up.  Thanks,
> > >
> > > Well, I think Greg just objected pretty strongly.
> > >
> > > IMHO it is wrong to turn mdev into some API multiplexor. That is
> > > what the driver core already does and AFAIK your bus type is
> > > supposed to represent your API contract to your drivers.
> > >
> > > Since the bus type is ABI, 'mdev' is really all about vfio I guess?
> > >
> > > Maybe mdev should grow by factoring the special GUID life cycle
> > > stuff into a helper library that can make it simpler to build proper
> > > API specific bus's using that lifecycle model? ie the virtio I saw
> > > proposed should probably be a mdev-virtio bus type providing this
> > > new virtio API contract using a 'struct mdev_virtio'?
> >
> > I see, the bus:API contract is more clear when we're talking about
> > physical buses and physical devices following a hardware
> > specification.
> 
> Well, I don't think it matters, this is a software contract inside the kernel
> between the 'struct foo_device' (as provided by the foo_bus) and the 'struct
> foo_driver'
> 
> This contract is certainly easier to define when a HW specification dictates
> basically how it works.
> 
> > But if we take PCI for example, each PCI device has it's own internal
> > API that operates on the bus API.  PCI bus drivers match devices based
> > on vendor and device ID, which defines that internal API, not the bus
> > API.
> 
> Yes, this matching is part of the API contract between the bus and device
> driver.
> 
> But all of the pci_* functions that accept a 'struct pci_device *' are also part of
> this API contract toward the driver.
> 
> > The bus API is pretty thin when we're talking virtual devices and
> > virtual buses though.  The bus "API" is essentially that lifecycle
> > management, so I'm having a bit of a hard time differentiating this
> 
> But Parav just pointed out to a virtio SW API that had something like
> 20 API entry points.
> 
> > instead?"  Essentially for virtual devices, we're dictating a bus per
> > device type, whereas it seemed like a reasonable idea at the time to
> 
> Well, what does a driver binding to a virtual device need to know?
> 
> The virtual device API should provide all of that information.
> 
> I think things like vfio and virtio APIs are very reasonable bus types. virtio in
> particular has a published 'hw-like' specification with some good layers that
> can build a bus API.
> 
> Not so sure about the very HW specific things like the Intel driver and these SFs.
> These will really only ever bind to one driver and seem to have no
> commonalities.
> 
> For those we either create a bus per driver-specific proprietary API (feels kind
> of wrong) or we have a generic bus essentially for managed multi-function
> hardware that uses a simple 'void *hw_data' as the driver API and some
> matching logic to support that.
> 
Its certainly important to use generic bus approach overall at kernel level so that every vendor doesn't define that own devlink flavor, id scheme, udev naming method, PM and so on.
(It is not just bus definition).

Coming to hw_data part, even if this subdev (vendor) bus is created, it can still exactly follow your foo_device example.

In fact my first published RFC [1] and its specific patch [2] was doing that.

probe() routine in series [1] didn't have PCI like struct subdev *, because I wanted to use the core's generic probe(),
However it still correct because probe() can reach out to foo_device using container_of().
And hence the *hw_data is also resolved.

So struct looks like,

struct subdev {
	struct device device;
	/* resource range */
	/* num of irq vectors */
	const char *hw_addr;
	[..]
};

struct mlx5_subdev {
	struct subdev device;
	[..];
};

I request to reconsider RFC [1] for multi-function SFs use with extension of device flavour as 'virtio', 'mlx5' etc in [3].

[1] https://lkml.org/lkml/2019/3/1/19
[2] https://lore.kernel.org/patchwork/patch/1046997/#1238851
[3] https://lkml.org/lkml/2019/3/1/25

> > create a common virtual device bus, but maybe it went into the weeds
> > when trying to figure out how device drivers match to devices on that
> > bus and actually interact with them.
> 
> I think it is important to focus on the the SW API the 'struct foo_device' is
> supposed to provide toward the driver that binds to it.
> 
> It should be a sensible API covering some well defined area..
> 
> Jason

  reply index

Thread overview: 132+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-07 16:04 Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 01/19] net/mlx5: E-switch, Move devlink port close to eswitch port Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 02/19] net/mlx5: E-Switch, Add SF vport, vport-rep support Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 03/19] net/mlx5: Introduce SF table framework Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 04/19] net/mlx5: Introduce SF life cycle APIs to allocate/free Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 05/19] net/mlx5: E-Switch, Enable/disable SF's vport during SF life cycle Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 06/19] net/mlx5: Add support for mediated devices in switchdev mode Parav Pandit
2019-11-08 10:32     ` Jiri Pirko
2019-11-08 16:03       ` Parav Pandit
2019-11-08 16:22         ` Jiri Pirko
2019-11-08 16:29           ` Parav Pandit
2019-11-08 18:01             ` Jiri Pirko
2019-11-08 18:04             ` Jiri Pirko
2019-11-08 18:21               ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 07/19] vfio/mdev: Introduce sha1 based mdev alias Parav Pandit
2019-11-08 11:04     ` Jiri Pirko
2019-11-08 15:59       ` Parav Pandit
2019-11-08 16:28         ` Jiri Pirko
2019-11-08 11:10     ` Cornelia Huck
2019-11-08 16:03       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 08/19] vfio/mdev: Make mdev alias unique among all mdevs Parav Pandit
2019-11-08 10:49     ` Jiri Pirko
2019-11-08 15:13       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 09/19] vfio/mdev: Expose mdev alias in sysfs tree Parav Pandit
2019-11-08 13:22     ` Jiri Pirko
2019-11-08 18:03       ` Alex Williamson
2019-11-08 18:16         ` Jiri Pirko
2019-11-07 16:08   ` [PATCH net-next 10/19] vfio/mdev: Introduce an API mdev_alias Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 11/19] vfio/mdev: Improvise mdev life cycle and parent removal scheme Parav Pandit
2019-11-08 13:01     ` Cornelia Huck
2019-11-08 16:12       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 12/19] devlink: Introduce mdev port flavour Parav Pandit
2019-11-07 20:38     ` Jakub Kicinski
2019-11-07 21:03       ` Parav Pandit
2019-11-08  1:17         ` Jakub Kicinski
2019-11-08  1:44           ` Parav Pandit
2019-11-08  2:20             ` Jakub Kicinski
2019-11-08  2:31               ` Parav Pandit
2019-11-08  9:46                 ` Jiri Pirko
2019-11-08 15:45                   ` Parav Pandit
2019-11-08 16:31                     ` Jiri Pirko
2019-11-08 16:43                       ` Parav Pandit
2019-11-08 18:11                         ` Jiri Pirko
2019-11-08 18:23                           ` Parav Pandit
2019-11-08 18:34                             ` Jiri Pirko
2019-11-08 18:56                               ` Parav Pandit
2019-11-08  9:30               ` Jiri Pirko
2019-11-08 15:41                 ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 13/19] net/mlx5: Register SF devlink port Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 14/19] net/mlx5: Share irqs between SFs and parent PCI device Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 15/19] net/mlx5: Add load/unload routines for SF driver binding Parav Pandit
2019-11-08  9:48     ` Jiri Pirko
2019-11-08 11:13       ` Jiri Pirko
2019-11-07 16:08   ` [PATCH net-next 16/19] net/mlx5: Implement dma ops and params for mediated device Parav Pandit
2019-11-07 20:42     ` Jakub Kicinski
2019-11-07 21:30       ` Parav Pandit
2019-11-08  1:16         ` Jakub Kicinski
2019-11-08  6:37     ` Christoph Hellwig
2019-11-08 15:29       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 17/19] net/mlx5: Add mdev driver to bind to mdev devices Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 18/19] Documentation: net: mlx5: Add mdev usage documentation Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 19/19] mtty: Optionally support mtty alias Parav Pandit
2019-11-08  6:26     ` Leon Romanovsky
2019-11-08 10:45     ` Jiri Pirko
2019-11-08 15:08       ` Parav Pandit
2019-11-08 15:15         ` Jiri Pirko
2019-11-08 13:46     ` Cornelia Huck
2019-11-08 15:10       ` Parav Pandit
2019-11-08 15:28         ` Cornelia Huck
2019-11-08 15:30           ` Parav Pandit
2019-11-08 17:54             ` Alex Williamson
2019-11-08  9:51   ` [PATCH net-next 01/19] net/mlx5: E-switch, Move devlink port close to eswitch port Jiri Pirko
2019-11-08 15:50     ` Parav Pandit
2019-11-07 17:03 ` [PATCH net-next 00/19] Mellanox, mlx5 sub function support Leon Romanovsky
2019-11-07 20:10   ` Parav Pandit
2019-11-08  6:20     ` Leon Romanovsky
2019-11-08 15:01       ` Parav Pandit
2019-11-07 20:32 ` Jakub Kicinski
2019-11-07 20:52   ` Parav Pandit
2019-11-08  1:16     ` Jakub Kicinski
2019-11-08  1:49       ` Parav Pandit
2019-11-08  2:12         ` Jakub Kicinski
2019-11-08 12:12   ` Jiri Pirko
2019-11-08 14:40     ` Jason Gunthorpe
2019-11-08 15:40       ` Parav Pandit
2019-11-08 19:12         ` Jakub Kicinski
2019-11-08 20:12           ` Jason Gunthorpe
2019-11-08 20:20             ` Parav Pandit
2019-11-08 20:32               ` Jason Gunthorpe
2019-11-08 20:52                 ` gregkh
2019-11-08 20:34             ` Alex Williamson
2019-11-08 21:05               ` Jason Gunthorpe
2019-11-08 21:19                 ` gregkh
2019-11-08 21:52                 ` Alex Williamson
2019-11-08 22:48                   ` Parav Pandit
2019-11-09  0:57                     ` Jason Gunthorpe
2019-11-09 17:41                       ` Jakub Kicinski
2019-11-10 19:04                         ` Jason Gunthorpe
2019-11-10 19:48                       ` Parav Pandit
2019-11-11 14:17                         ` Jiri Pirko
2019-11-11 14:58                           ` Parav Pandit
2019-11-11 15:06                             ` Jiri Pirko
2019-11-19  4:51                               ` Parav Pandit
2019-11-09  0:12                   ` Jason Gunthorpe
2019-11-09  0:45                     ` Parav Pandit [this message]
2019-11-11  2:19                 ` Jason Wang
2019-11-08 21:45             ` Jakub Kicinski
2019-11-09  0:44               ` Jason Gunthorpe
2019-11-09  8:46                 ` gregkh
2019-11-09 11:18                   ` Jiri Pirko
2019-11-09 17:28                     ` Jakub Kicinski
2019-11-10  9:16                     ` gregkh
2019-11-09 17:27                 ` Jakub Kicinski
2019-11-10  9:18                   ` gregkh
2019-11-11  3:46                     ` Jakub Kicinski
2019-11-11  5:18                       ` Parav Pandit
2019-11-11 13:30                       ` Jiri Pirko
2019-11-11 14:14                         ` gregkh
2019-11-11 14:37                           ` Jiri Pirko
2019-11-10 19:37                   ` Jason Gunthorpe
2019-11-11  3:57                     ` Jakub Kicinski
2019-11-08 16:06     ` Parav Pandit
2019-11-08 19:06     ` Jakub Kicinski
2019-11-08 19:34       ` Parav Pandit
2019-11-08 19:48         ` Jakub Kicinski
2019-11-08 19:41       ` Jiri Pirko
2019-11-08 20:40         ` Parav Pandit
2019-11-08 21:21         ` Jakub Kicinski
2019-11-08 21:39           ` Jiri Pirko
2019-11-08 21:51             ` Jakub Kicinski
2019-11-08 22:21               ` Jiri Pirko
2019-11-07 23:57 ` David Miller

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=AM0PR05MB4866C174D5DAC301D97B8324D17A0@AM0PR05MB4866.eurprd05.prod.outlook.com \
    --to=parav@mellanox.com \
    --cc=alex.williamson@redhat.com \
    --cc=cohuck@redhat.com \
    --cc=davem@davemloft.net \
    --cc=david.m.ertman@intel.com \
    --cc=gerlitz.or@gmail.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=jakub.kicinski@netronome.com \
    --cc=jasowang@redhat.com \
    --cc=jgg@ziepe.ca \
    --cc=jiri@mellanox.com \
    --cc=jiri@resnulli.us \
    --cc=kvm@vger.kernel.org \
    --cc=kwankhede@nvidia.com \
    --cc=leon@kernel.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=saeedm@mellanox.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Netdev Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/netdev/0 netdev/git/0.git
	git clone --mirror https://lore.kernel.org/netdev/1 netdev/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 netdev netdev/ https://lore.kernel.org/netdev \
		netdev@vger.kernel.org
	public-inbox-index netdev

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.netdev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git