From: Cornelia Huck <cohuck@redhat.com>
To: Max Gurtovoy <mgurtovoy@nvidia.com>
Cc: <alex.williamson@redhat.com>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <jgg@nvidia.com>,
<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 14:38:06 +0100 [thread overview]
Message-ID: <20210118143806.036c8dbc.cohuck@redhat.com> (raw)
In-Reply-To: <20210117181534.65724-1-mgurtovoy@nvidia.com>
On Sun, 17 Jan 2021 18:15:31 +0000
Max Gurtovoy <mgurtovoy@nvidia.com> wrote:
> Hi Alex and Cornelia,
>
> This series split the vfio_pci driver into 2 parts: pci driver and a
> subsystem driver that will also be library of code. The pci driver,
> vfio_pci.ko will be used as before and it will bind to the subsystem
> driver vfio_pci_core.ko to register to the VFIO subsystem. This patchset
> if fully backward compatible. This is a typical Linux subsystem
> framework behaviour. This framework can be also adopted by vfio_mdev
> devices as we'll see in the below sketch.
>
> This series is coming to solve the issues that were raised in the
> previous attempt for extending vfio-pci for vendor specific
> functionality: https://lkml.org/lkml/2020/5/17/376 by Yan Zhao.
>
> This solution is also deterministic in a sense that when a user will
> bind to a vendor specific vfio-pci driver, it will get all the special
> goodies of the HW.
>
> This subsystem framework will also ease on adding vendor specific
> functionality to VFIO devices in the future by allowing another module
> to provide the pci_driver that can setup number of details before
> registering to VFIO subsystem (such as inject its own operations).
>
> Below we can see the proposed changes (this patchset only deals with
> VFIO_PCI subsystem but it can easily be extended to VFIO_MDEV subsystem
> as well):
>
> +----------------------------------------------------------------------+
> | |
> | VFIO |
> | |
> +----------------------------------------------------------------------+
>
> +--------------------------------+ +--------------------------------+
> | | | |
> | VFIO_PCI_CORE | | VFIO_MDEV_CORE |
> | | | |
> +--------------------------------+ +--------------------------------+
>
> +---------------+ +--------------+ +---------------+ +--------------+
> | | | | | | | |
> | | | | | | | |
> | VFIO_PCI | | MLX5_VFIO_PCI| | VFIO_MDEV | |MLX5_VFIO_MDEV|
> | | | | | | | |
> | | | | | | | |
> +---------------+ +--------------+ +---------------+ +--------------+
>
> First 2 patches introduce the above changes for vfio_pci and
> vfio_pci_core.
>
> Patch (3/3) introduces a new mlx5 vfio-pci module that registers to VFIO
> subsystem using vfio_pci_core. It also registers to Auxiliary bus for
> binding to mlx5_core that is the parent of mlx5-vfio-pci devices. This
> will allow extending mlx5-vfio-pci devices with HW specific features
> such as Live Migration (mlx5_core patches are not part of this series
> that comes for proposing the changes need for the vfio pci subsystem).
>
> 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?); 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?
>
> In this way, we'll use the HW vendor driver core to manage the lifecycle
> of these devices. This is reasonable since only the vendor driver knows
> exactly about the status on its internal state and the capabilities of
> its acceleratots, for example.
>
> TODOs:
> 1. For this RFC we still haven't cleaned all vendor specific stuff that
> were merged in the past into vfio_pci (such as VFIO_PCI_IG and
> VFIO_PCI_NVLINK2).
> 2. Create subsystem module for VFIO_MDEV. This can be used for vendor
> specific scalable functions for example (SFs).
> 3. Add Live migration functionality for mlx5 SNAP devices
> (NVMe/Virtio-BLK).
> 4. Add Live migration functionality for mlx5 VFs
> 5. Add the needed functionality for mlx5_core
>
> I would like to thank the great team that was involved in this
> development, design and internal review:
> Oren, Liran, Jason, Leon, Aviad, Shahaf, Gary, Artem, Kirti, Neo, Andy
> and others.
>
> This series applies cleanly on top of kernel 5.11-rc2+ commit 2ff90100ace8:
> "Merge tag 'hwmon-for-v5.11-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging"
> from Linus.
>
> Note: Live migration for MLX5 SNAP devices is WIP and will be the first
> example for adding vendor extension to vfio-pci devices. As the
> changes to the subsystem must be defined as a pre-condition for
> this work, we've decided to split the submission for now.
>
> Max Gurtovoy (3):
> vfio-pci: rename vfio_pci.c to vfio_pci_core.c
> vfio-pci: introduce vfio_pci_core subsystem driver
> mlx5-vfio-pci: add new vfio_pci driver for mlx5 devices
>
> 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... from a quick glance at patch 3,
it mostly forwards to vfio_pci_core anyway. Do you expect a huge amount
of device-specific callback invocations?
[I have not looked at this in detail yet.]
> drivers/vfio/pci/vfio_pci_private.h | 21 +
> include/linux/mlx5/vfio_pci.h | 36 +
> 7 files changed, 2734 insertions(+), 2311 deletions(-)
> create mode 100644 drivers/vfio/pci/mlx5_vfio_pci.c
> create mode 100644 drivers/vfio/pci/vfio_pci_core.c
> create mode 100644 include/linux/mlx5/vfio_pci.h
>
next prev parent reply other threads:[~2021-01-18 13:40 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 ` Cornelia Huck [this message]
2021-01-18 15:10 ` [PATCH RFC v1 0/3] Introduce vfio-pci-core subsystem Jason Gunthorpe
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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