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From: Jason Gunthorpe <jgg@nvidia.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: Max Gurtovoy <mgurtovoy@nvidia.com>, <alex.williamson@redhat.com>,
	<kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<liranl@nvidia.com>, <oren@nvidia.com>, <tzahio@nvidia.com>,
	<leonro@nvidia.com>, <yarong@nvidia.com>, <aviadye@nvidia.com>,
	<shahafs@nvidia.com>, <artemp@nvidia.com>, <kwankhede@nvidia.com>,
	<ACurrid@nvidia.com>, <gmataev@nvidia.com>, <cjia@nvidia.com>
Subject: Re: [PATCH RFC v1 0/3] Introduce vfio-pci-core subsystem
Date: Mon, 18 Jan 2021 11:10:20 -0400	[thread overview]
Message-ID: <20210118151020.GJ4147@nvidia.com> (raw)
In-Reply-To: <20210118143806.036c8dbc.cohuck@redhat.com>

On Mon, Jan 18, 2021 at 02:38:06PM +0100, Cornelia Huck wrote:

> > These devices will be seen on the Auxiliary bus as:
> > mlx5_core.vfio_pci.2048 -> ../../../devices/pci0000:00/0000:00:02.0/0000:05:00.0/0000:06:00.0/0000:07:00.0/mlx5_core.vfio_pci.2048
> > mlx5_core.vfio_pci.2304 -> ../../../devices/pci0000:00/0000:00:02.0/0000:05:00.0/0000:06:00.0/0000:07:00.1/mlx5_core.vfio_pci.2304
> > 
> > 2048 represents BDF 08:00.0 and 2304 represents BDF 09:00.0 in decimal
> > view. In this manner, the administrator will be able to locate the
> > correct vfio-pci module it should bind the desired BDF to (by finding
> > the pointer to the module according to the Auxiliary driver of that
> > BDF).
> 
> I'm not familiar with that auxiliary framework (it seems to be fairly
> new?); 

Auxillary bus is for connecting two parts of the same driver that
reside in different modules/subystems. Here it is connecting the vfio
part to the core part of mlx5 (running on the PF).

> but can you maybe create an auxiliary device unconditionally and
> contain all hardware-specific things inside a driver for it? Or is
> that not flexible enough?

The goal is to make a vfio device, auxiliary bus is only in the
picture because a VF device under vfio needs to interact with the PF
mlx5_core driver, auxiliary bus provides that connection.

You can say that all the HW specific things are in the mlx5_vfio_pci
driver. It is an unusual driver because it must bind to both the PCI
VF with a pci_driver and to the mlx5_core PF using an
auxiliary_driver. This is needed for the object lifetimes to be
correct.

The PF is providing services to control a full VF which mlx5_vfio_pci
converts into VFIO API.

> >  drivers/vfio/pci/Kconfig            |   22 +-
> >  drivers/vfio/pci/Makefile           |   16 +-
> >  drivers/vfio/pci/mlx5_vfio_pci.c    |  253 +++
> >  drivers/vfio/pci/vfio_pci.c         | 2386 +--------------------------
> >  drivers/vfio/pci/vfio_pci_core.c    | 2311 ++++++++++++++++++++++++++
> 
> Especially regarding this diffstat... 

It is a bit misleading because it doesn't show the rename

Jason

  reply	other threads:[~2021-01-18 16:54 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-17 18:15 [PATCH RFC v1 0/3] Introduce vfio-pci-core subsystem Max Gurtovoy
2021-01-17 18:15 ` [PATCH 1/3] vfio-pci: rename vfio_pci.c to vfio_pci_core.c Max Gurtovoy
2021-01-17 18:15 ` [PATCH 2/3] vfio-pci: introduce vfio_pci_core subsystem driver Max Gurtovoy
2021-01-17 18:15 ` [PATCH 3/3] mlx5-vfio-pci: add new vfio_pci driver for mlx5 devices Max Gurtovoy
2021-01-18 13:38 ` [PATCH RFC v1 0/3] Introduce vfio-pci-core subsystem Cornelia Huck
2021-01-18 15:10   ` Jason Gunthorpe [this message]
2021-01-18 16:00     ` Cornelia Huck
2021-01-18 18:16       ` Jason Gunthorpe
2021-01-19 18:56         ` Cornelia Huck
2021-01-19 19:42           ` Jason Gunthorpe
2021-01-22 19:25 ` Alex Williamson
2021-01-22 20:04   ` Jason Gunthorpe
2021-01-25 16:20     ` Cornelia Huck
2021-01-25 18:04       ` Jason Gunthorpe
2021-01-25 23:31         ` Alex Williamson
2021-01-26  0:45           ` Jason Gunthorpe
2021-01-26  3:34             ` Alex Williamson
2021-01-26 13:27               ` Max Gurtovoy
2021-01-28 16:29                 ` Cornelia Huck
2021-01-28 21:02                   ` Alex Williamson
2021-01-31 18:46                     ` Max Gurtovoy
2021-02-01  4:32                       ` Alex Williamson
2021-02-01  9:40                         ` Max Gurtovoy
2021-02-01 17:29                           ` Alex Williamson
2021-02-01 17:17                         ` Jason Gunthorpe
2021-01-31 18:09                   ` Max Gurtovoy
2021-01-26 17:23               ` Jason Gunthorpe

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