[PATCH v4 00/55] drivers: hv: dxgkrnl: Driver for Hyper-V virtual compute device

[Eric Curtin <ericcurtin17@gmail.com>]

This patch series introduces the dxgkrnl driver, which provides Linux
support for virtual compute devices (vGPUs) paravirtualized by a Windows
Hyper-V host. The primary use case is Windows Subsystem for Linux (WSL2),
where the driver enables GPU-accelerated workloads inside Linux containers
running on Windows.

The driver creates /dev/dxg, a miscdevice that user-space API libraries
(such as the open-source libdxg) use to communicate with virtual GPU
adapters via IOCTLs implementing a subset of the WDDM/MCDM D3DKMT
interface. Physical GPU access is performed entirely on the Windows host;
the guest driver communicates over Hyper-V VMBus channels.

Key characteristics:
 - Self-contained under drivers/hv/dxgkrnl/
 - Depends only on CONFIG_HYPERV, DMA_SHARED_BUFFER, SYNC_FILE
 - Supports multiple vGPU adapters per VM
 - DMA fence integration via dxgsyncfile (SYNC_FILE)
 - Supports compute-only accelerators (AI/ML workloads) as well as
   full graphics adapters

Changes since v3 (posted March 2022):
 - Replace deprecated one-element arrays [1] with C99 flexible arrays []
 - Replace %px with %p in trace macros
 - Remove unnecessary braces from single-statement if blocks
 - Remove LINUX_VERSION_CODE guard for max_pkt_size (added in 5.15,
   well before any target kernel for this submission)
 - Remove linux/version.h include (no longer needed)
 - Fix whitespace issues flagged by checkpatch
 - Replace non-debug DXG_ERR do{}while(0) macro with direct dev_err call
 - Change -EBADE to -ENODEV for global channel duplicate detection
   (as requested by Greg KH in v3 review)
 - Remove MODULE_VERSION (not recommended for in-tree drivers)
 - Add explanatory comment to guid_to_luid() cast
 - Additional features and fixes developed in the WSL2 fork:
   * dxgsyncfile: DMA fence / sync file integration
   * D3DKMTEnumProcesses, D3DDKMTIsFeatureEnabled, D3DKMTInvalidateCache
   * Compute-only adapter support
   * pin_user_pages for DMA-accessible memory
   * Retry logic for VMBus ring buffer full condition
   * Various synchronization and memory safety fixes

Regarding the dxgglobal singleton raised in v3 review:
The design reflects a host architecture constraint: each Hyper-V VM has
exactly one global VMBus channel offered by the host, regardless of how
many vGPU adapters are present. The dxgglobal structure encapsulates this
VM-level state (global channel, adapter list, process list, host event
tracking). Per-adapter state is separately managed in dxgadapter objects.
This design was previously explained in the v3 thread; the architecture
matches the Hyper-V GPU-PV protocol which is fixed by the host side.

The patches apply on top of v6.6-lts. The user-space library (libdxg)
that communicates with this driver is available at:
  https://github.com/microsoft/libdxg

The full WDDM compute stack (OpenCL, oneAPI, OpenVINO) is available
open-source via Intel's compute-runtime project.

Iouri Tarassov (iourit@linux.microsoft.com) is the primary author and
maintainer of this driver.

Eric Curtin (1):
  drivers: hv: dxgkrnl: Fix checkpatch issues and address reviewer
    feedback

Hideyuki Nagase (1):
  drivers: hv: dxgkrnl: Fix crash at hmgrtable_free_handle

Iouri Tarassov (53):
  drivers: hv: dxgkrnl: Driver initialization and loading
  drivers: hv: dxgkrnl: Add VMBus message support, initialize VMBus
    channels.
  drivers: hv: dxgkrnl: Creation of dxgadapter object
  drivers: hv: dxgkrnl: Opening of /dev/dxg device and dxgprocess
    creation
  drivers: hv: dxgkrnl: Enumerate and open dxgadapter objects
  drivers: hv: dxgkrnl: Creation of dxgdevice objects
  drivers: hv: dxgkrnl: Creation of dxgcontext objects
  drivers: hv: dxgkrnl: Creation of compute device allocations and
    resources
  drivers: hv: dxgkrnl: Creation of compute device sync objects
  drivers: hv: dxgkrnl: Operations using sync objects
  drivers: hv: dxgkrnl: Sharing of dxgresource objects
  drivers: hv: dxgkrnl: Sharing of sync objects
  drivers: hv: dxgkrnl: Creation of paging queue objects.
  drivers: hv: dxgkrnl: Submit execution commands to the compute device
  drivers: hv: dxgkrnl: Share objects with the host
  drivers: hv: dxgkrnl: Query the dxgdevice state
  drivers: hv: dxgkrnl: Map(unmap) CPU address to device allocation
  drivers: hv: dxgkrnl: Manage device allocation properties
  drivers: hv: dxgkrnl: Flush heap transitions
  drivers: hv: dxgkrnl: Query video memory information
  drivers: hv: dxgkrnl: The escape ioctl
  drivers: hv: dxgkrnl: Ioctl to put device to error state
  drivers: hv: dxgkrnl: Ioctls to query statistics and clock calibration
  drivers: hv: dxgkrnl: Offer and reclaim allocations
  drivers: hv: dxgkrnl: Ioctls to manage scheduling priority
  drivers: hv: dxgkrnl: Manage residency of allocations
  drivers: hv: dxgkrnl: Manage compute device virtual addresses
  drivers: hv: dxgkrnl: Add support to map guest pages by host
  drivers: hv: dxgkrnl: Removed struct vmbus_gpadl, which was defined in
    the main linux branch
  drivers: hv: dxgkrnl: Remove dxgk_init_ioctls
  drivers: hv: dxgkrnl: Creation of dxgsyncfile objects
  drivers: hv: dxgkrnl: Use tracing instead of dev_dbg
  drivers: hv: dxgkrnl: Implement D3DKMTWaitSyncFile
  drivers: hv: dxgkrnl: Improve tracing and return values from copy from
    user
  drivers: hv: dxgkrnl: Fix synchronization locks
  drivers: hv: dxgkrnl: Close shared file objects in case of a failure
  drivers: hv: dxgkrnl: Added missed NULL check for resource object
  drivers: hv: dxgkrnl: Fixed dxgkrnl to build for the 6.1 kernel
  drivers: hv: dxgkrnl: Added support for compute only adapters
  drivers: hv: dxgkrnl: Added implementation for D3DKMTInvalidateCache
  drivers: hv: dxgkrnl: Handle process ID in D3DKMTQueryStatistics
  drivers: hv: dxgkrnl: Implement the D3DKMTEnumProcesses API
  drivers: hv: dxgkrnl: Implement D3DDKMTIsFeatureEnabled API
  drivers: hv: dxgkrnl: Implement known escapes
  drivers: hv: dxgkrnl: Fixed coding style issues
  drivers: hv: dxgkrnl: Fixed the implementation of
    D3DKMTQueryClockCalibration
  drivers: hv: dxgkrnl: Retry sending a VM bus packet when there is no
    place in the ring buffer
  drivers: hv: dxgkrnl: Add support for locking a shared allocation by
    not the owner
  drivers: hv: dxgkrnl: Fix build breaks when switching to 6.6 kernel
    due to hv_driver remove callback change.
  drivers: hv: dxgkrnl: Fix build breaks when switching to 6.6 kernel
    due to removed uuid_le_cmp
  drivers: hv: dxgkrnl: Implement D3DKMTEnumProcesses to match the
    Windows implementation
  drivers: hv: dxgkrnl: Use pin_user_pages instead of get_user_pages for
    DMA accessible memory
  drivers: hv: dxgkrnl: Do not print error messages when virtual GPU is
    not present

 MAINTAINERS                      |    7 +
 drivers/hv/Kconfig               |    2 +
 drivers/hv/Makefile              |    1 +
 drivers/hv/dxgkrnl/Kconfig       |   28 +
 drivers/hv/dxgkrnl/Makefile      |    5 +
 drivers/hv/dxgkrnl/dxgadapter.c  | 1367 ++++++++
 drivers/hv/dxgkrnl/dxgkrnl.h     | 1042 ++++++
 drivers/hv/dxgkrnl/dxgmodule.c   |  971 +++++
 drivers/hv/dxgkrnl/dxgprocess.c  |  348 ++
 drivers/hv/dxgkrnl/dxgsyncfile.c |  481 +++
 drivers/hv/dxgkrnl/dxgsyncfile.h |   33 +
 drivers/hv/dxgkrnl/dxgvmbus.c    | 3992 +++++++++++++++++++++
 drivers/hv/dxgkrnl/dxgvmbus.h    |  910 +++++
 drivers/hv/dxgkrnl/hmgr.c        |  567 +++
 drivers/hv/dxgkrnl/hmgr.h        |  112 +
 drivers/hv/dxgkrnl/ioctl.c       | 5648 ++++++++++++++++++++++++++++++
 drivers/hv/dxgkrnl/misc.c        |   38 +
 drivers/hv/dxgkrnl/misc.h        |   96 +
 include/uapi/misc/d3dkmthk.h     | 1794 ++++++++++
 19 files changed, 17442 insertions(+)
 create mode 100644 drivers/hv/dxgkrnl/Kconfig
 create mode 100644 drivers/hv/dxgkrnl/Makefile
 create mode 100644 drivers/hv/dxgkrnl/dxgadapter.c
 create mode 100644 drivers/hv/dxgkrnl/dxgkrnl.h
 create mode 100644 drivers/hv/dxgkrnl/dxgmodule.c
 create mode 100644 drivers/hv/dxgkrnl/dxgprocess.c
 create mode 100644 drivers/hv/dxgkrnl/dxgsyncfile.c
 create mode 100644 drivers/hv/dxgkrnl/dxgsyncfile.h
 create mode 100644 drivers/hv/dxgkrnl/dxgvmbus.c
 create mode 100644 drivers/hv/dxgkrnl/dxgvmbus.h
 create mode 100644 drivers/hv/dxgkrnl/hmgr.c
 create mode 100644 drivers/hv/dxgkrnl/hmgr.h
 create mode 100644 drivers/hv/dxgkrnl/ioctl.c
 create mode 100644 drivers/hv/dxgkrnl/misc.c
 create mode 100644 drivers/hv/dxgkrnl/misc.h
 create mode 100644 include/uapi/misc/d3dkmthk.h