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 manager 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. This series incorporates a version of the mlx5ctl interface previously proposed: https://lore.kernel.org/r/20240207072435.14182-1-saeed@xxxxxxxxxx/ For this series the memory registration mechanism was removed, but I expect it will come back. This series comes with mlx5 as a driver implementation, and I have soft commitments for at least three more drivers. There have been two LWN articles written discussing various aspects of this proposal: https://lwn.net/Articles/955001/ https://lwn.net/Articles/969383/ Several have expressed general support for this concept: Broadcom Networking - https://lore.kernel.org/r/Zf2n02q0GevGdS-Z@C02YVCJELVCG Christoph Hellwig - https://lore.kernel.org/r/Zcx53N8lQjkpEu94@xxxxxxxxxxxxx/ Enfabrica - https://lore.kernel.org/r/9cc7127f-8674-43bc-b4d7-b1c4c2d96fed@xxxxxxxxxx/ NVIDIA Networking Oracle Linux - https://lore.kernel.org/r/6lakj6lxlxhdgrewodvj3xh6sxn3d36t5dab6najzyti2navx3@wrge7cyfk6nq Work is ongoing for a robust multi-device open source userspace, currently the mlx5ctl_user that was posted by Saeed has been updated to use fwctl. https://github.com/saeedtx/mlx5ctl.git https://github.com/jgunthorpe/mlx5ctl.git This is on github: https://github.com/jgunthorpe/linux/commits/fwctl 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.rst | 269 ++++++++++++ Documentation/userspace-api/index.rst | 1 + .../userspace-api/ioctl/ioctl-number.rst | 1 + MAINTAINERS | 16 + drivers/Kconfig | 2 + drivers/Makefile | 1 + drivers/fwctl/Kconfig | 23 + drivers/fwctl/Makefile | 5 + drivers/fwctl/main.c | 411 ++++++++++++++++++ drivers/fwctl/mlx5/Makefile | 4 + drivers/fwctl/mlx5/main.c | 333 ++++++++++++++ drivers/net/ethernet/mellanox/mlx5/core/dev.c | 8 + include/linux/fwctl.h | 112 +++++ include/linux/panic.h | 3 +- include/uapi/fwctl/fwctl.h | 137 ++++++ include/uapi/fwctl/mlx5.h | 36 ++ kernel/panic.c | 1 + 18 files changed, 1367 insertions(+), 1 deletion(-) create mode 100644 Documentation/userspace-api/fwctl.rst create mode 100644 drivers/fwctl/Kconfig create mode 100644 drivers/fwctl/Makefile 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/fwctl.h create mode 100644 include/uapi/fwctl/mlx5.h base-commit: c3f38fa61af77b49866b006939479069cd451173 -- 2.45.2
