Re: [PATCH v4 00/10] Introduce fwctl subystem

[Dave Jiang <dave.jiang@intel.com>]

On 2/6/25 5:13 PM, Jason Gunthorpe wrote:
> [
> Many people were away around the holiday period, but work is back in full
> swing now with Dave already at v3 on his CXL work over the past couple
> weeks. We are looking at a good chance of reaching this merge window. I
> will work out some shared branches with CXL and get it into linux-next
> once all three drivers can be assembled and reviews seem to be concluding.
> 
> There are couple open notes
>  - Greg was interested in a new name, but nobody offered any bikesheds
>  - I would like a co-maintainer

I volunteer as tribute. :) 

I got the CXL series rebased and tested on top of this series. So you can add
Tested-by: Dave Jiang <dave.jiang@intel.com>
for the core FWCTL bits in the series.

I'll post the CXL FWCTL series v4 shortly.

DJ

> ]
> 
> fwctl is a new subsystem intended to bring some common rules and order to
> the growing pattern of exposing a secure FW interface directly to
> userspace. Unlike existing places like RDMA/DRM/VFIO/uacce that are
> exposing a device for datapath operations fwctl is focused on debugging,
> configuration and provisioning of the device. It will not have the
> necessary features like interrupt delivery to support a datapath.
> 
> This concept is similar to the long standing practice in the "HW" RAID
> space of having a device specific misc device to manage the RAID
> controller FW. fwctl generalizes this notion of a companion debug and
> management interface that goes along with a dataplane implemented in an
> appropriate subsystem.
> 
> The need for this has reached a critical point as many users are moving to
> run lockdown enabled kernels. Several existing devices have had long
> standing tooling for management that relied on /sys/../resource0 or PCI
> config space access which is not permitted in lockdown. A major point of
> fwctl is to define and document the rules that a device must follow to
> expose a lockdown compatible RPC.
> 
> Based on some discussion fwctl splits the RPCs into four categories
> 
> 	FWCTL_RPC_CONFIGURATION
> 	FWCTL_RPC_DEBUG_READ_ONLY
> 	FWCTL_RPC_DEBUG_WRITE
> 	FWCTL_RPC_DEBUG_WRITE_FULL
> 
> Where the latter two trigger a new TAINT_FWCTL, and the final one requires
> CAP_SYS_RAWIO - excluding it from lockdown. The device driver and its FW
> would be responsible to restrict RPCs to the requested security scope,
> while the core code handles the tainting and CAP checks.
> 
> For details see the final patch which introduces the documentation.
> 
> The CXL FWCTL driver is now in it own series on v3:
>  https://lore.kernel.org/r/20250204220430.4146187-1-dave.jiang@intel.com
> 
> I'm expecting a 3rd driver (from Shannon @ Pensando) to be posted right
> away, the github version I saw looked good. I've got soft commitments for
> about 6 drivers in total now.
> 
> There have been three LWN articles written discussing various aspects of
> this proposal:
> 
>  https://lwn.net/Articles/955001/
>  https://lwn.net/Articles/969383/
>  https://lwn.net/Articles/990802/
> 
> A really giant ksummit thread preceding a discussion at the Maintainer
> Summit:
> 
>  https://lore.kernel.org/ksummit/668c67a324609_ed99294c0@dwillia2-xfh.jf.intel.com.notmuch/
> 
> Several have expressed general support for this concept:
> 
>  AMD/Pensando - https://lore.kernel.org/linux-rdma/20241205222818.44439-1-shannon.nelson@amd.com
>  Broadcom Networking - https://lore.kernel.org/r/Zf2n02q0GevGdS-Z@C02YVCJELVCG
>  Christoph Hellwig - https://lore.kernel.org/r/Zcx53N8lQjkpEu94@infradead.org
>  Daniel Vetter - https://lore.kernel.org/r/ZrHY2Bds7oF7KRGz@phenom.ffwll.local
>  Enfabrica - https://lore.kernel.org/r/9cc7127f-8674-43bc-b4d7-b1c4c2d96fed@kernel.org
>  NVIDIA Networking
>  Oded Gabbay/Habana - https://lore.kernel.org/r/ZrMl1bkPP-3G9B4N@T14sgabbay.
>  Oracle Linux - https://lore.kernel.org/r/6lakj6lxlxhdgrewodvj3xh6sxn3d36t5dab6najzyti2navx3@wrge7cyfk6nq
>  SuSE/Hannes - https://lore.kernel.org/r/2fd48f87-2521-4c34-8589-dbb7e91bb1c8@suse.com
> 
> Work is ongoing for userspace, currently the mellanox tool suite has been
> ported over:
>   https://github.com/Mellanox/mstflint
> 
> And a more simplified example how to use it:
>   https://github.com/jgunthorpe/mlx5ctl.git
> 
> This is on github: https://github.com/jgunthorpe/linux/commits/fwctl
> 
> v4:
>  - Rebase to v6.14-rc1
>  - Fine tune comments and rst documentatin
>  - Adjust cleanup.h usage - remove places that add more ofuscation than
>    value
>  - CXL is back to its own independent series
>  - Increase FWCTL_MAX_DEVICES to 4096, someone hit the limit
>  - Fix mlx5ctl_validate_rpc() logic around scope checking
>  - Disable mlx5ctl on SFs
> v3: https://patch.msgid.link/r/0-v3-960f17f90f17+516-fwctl_jgg@nvidia.com
>  - Rebase to v6.11-rc4
>  - Add a squashed version of David's CXL series as the 2nd driver
>  - Add missing includes
>  - Improve comments based on feedback
>  - Use the kdoc format that puts the member docs inside the struct
>  - Rewrite fwctl_alloc_device() to be clearer
>  - Incorporate all remarks for the documentation
> v2: https://lore.kernel.org/r/0-v2-940e479ceba9+3821-fwctl_jgg@nvidia.com
>  - Rebase to v6.10-rc5
>  - Minor style changes
>  - Follow the style consensus for the guard stuff
>  - Documentation grammer/spelling
>  - Add missed length output for mlx5 get_info
>  - Add two more missed MLX5 CMD's
>  - Collect tags
> v1: https://lore.kernel.org/r/0-v1-9912f1a11620+2a-fwctl_jgg@nvidia.com
> 
> Andy Gospodarek (2):
>   fwctl/bnxt: Support communicating with bnxt fw
>   bnxt: Create an auxiliary device for fwctl_bnxt
> 
> Jason Gunthorpe (6):
>   fwctl: Add basic structure for a class subsystem with a cdev
>   fwctl: Basic ioctl dispatch for the character device
>   fwctl: FWCTL_INFO to return basic information about the device
>   taint: Add TAINT_FWCTL
>   fwctl: FWCTL_RPC to execute a Remote Procedure Call to device firmware
>   fwctl: Add documentation
> 
> Saeed Mahameed (2):
>   fwctl/mlx5: Support for communicating with mlx5 fw
>   mlx5: Create an auxiliary device for fwctl_mlx5
> 
>  Documentation/admin-guide/tainted-kernels.rst |   5 +
>  Documentation/userspace-api/fwctl/fwctl.rst   | 285 ++++++++++++
>  Documentation/userspace-api/fwctl/index.rst   |  12 +
>  Documentation/userspace-api/index.rst         |   1 +
>  .../userspace-api/ioctl/ioctl-number.rst      |   1 +
>  MAINTAINERS                                   |  16 +
>  drivers/Kconfig                               |   2 +
>  drivers/Makefile                              |   1 +
>  drivers/fwctl/Kconfig                         |  32 ++
>  drivers/fwctl/Makefile                        |   6 +
>  drivers/fwctl/bnxt/Makefile                   |   4 +
>  drivers/fwctl/bnxt/bnxt.c                     | 167 +++++++
>  drivers/fwctl/main.c                          | 416 ++++++++++++++++++
>  drivers/fwctl/mlx5/Makefile                   |   4 +
>  drivers/fwctl/mlx5/main.c                     | 340 ++++++++++++++
>  drivers/net/ethernet/broadcom/bnxt/bnxt.c     |   3 +
>  drivers/net/ethernet/broadcom/bnxt/bnxt.h     |   3 +
>  drivers/net/ethernet/broadcom/bnxt/bnxt_ulp.c | 126 +++++-
>  drivers/net/ethernet/broadcom/bnxt/bnxt_ulp.h |   4 +
>  drivers/net/ethernet/mellanox/mlx5/core/dev.c |   9 +
>  include/linux/fwctl.h                         | 135 ++++++
>  include/linux/panic.h                         |   3 +-
>  include/uapi/fwctl/bnxt.h                     |  27 ++
>  include/uapi/fwctl/fwctl.h                    | 140 ++++++
>  include/uapi/fwctl/mlx5.h                     |  36 ++
>  kernel/panic.c                                |   1 +
>  tools/debugging/kernel-chktaint               |   8 +
>  27 files changed, 1782 insertions(+), 5 deletions(-)
>  create mode 100644 Documentation/userspace-api/fwctl/fwctl.rst
>  create mode 100644 Documentation/userspace-api/fwctl/index.rst
>  create mode 100644 drivers/fwctl/Kconfig
>  create mode 100644 drivers/fwctl/Makefile
>  create mode 100644 drivers/fwctl/bnxt/Makefile
>  create mode 100644 drivers/fwctl/bnxt/bnxt.c
>  create mode 100644 drivers/fwctl/main.c
>  create mode 100644 drivers/fwctl/mlx5/Makefile
>  create mode 100644 drivers/fwctl/mlx5/main.c
>  create mode 100644 include/linux/fwctl.h
>  create mode 100644 include/uapi/fwctl/bnxt.h
>  create mode 100644 include/uapi/fwctl/fwctl.h
>  create mode 100644 include/uapi/fwctl/mlx5.h
> 
> 
> base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b