drivers: hv: dxgkrnl: Driver initialization and creation of dxgadapter

- Add support for a Hyper-V based vGPU implementation that exposes the
  DirectX API to Linux userspace.
- Handle driver loading, registration for the PCI and VM bus device
  notifications
- Add headers for user mode interfaces, internal driver objects and VM bus
  communication interface
- Handle initialization of VM bus channels and creation of the dxgadapter
  object
- Removed dxg_copy_from_user and dxg_copy_to_user
- Connect the dxgkrnl module to the drivers/hv/ makefile and Kconfig.
- Create a MAINTAINERS entry

PCI driver registration

A PCI device is created for each virtual GPU (vGPU) device, projected by
the host. The device vendor is PCI_VENDOR_ID_MICROSOFT and device id is
PCI_DEVICE_ID_VIRTUAL_RENDER. dxg_pci_probe_device handles arrival of such
devices and it creates dxgadapter objects. The PCI config space of the
vGPU device has luid of the corresponding per GPU VM bus channel. This is
how the adapters are linked to VM bus channels.

dxgadapter initialization

A dxgadapter object represents a virtual GPU, projected to the VM by the
host. This object can start functioning only when the global VM bus
channel and the corresponding per vGPU VM bus channel are initialized in
the guest. Notifications about arrival of vGPU PCI device and VM bus
channels can happen in any order. Therefore, the initial dxgadapter object
state is DXGADAPTER_STATE_WAITING_VMBUS. A list of VM bus channels and a
list of dxgadapter objects are created. When dxgkrnl is notified about a
VM bus channel arrival, if tries to start all adapters, which are not
started yet.

VM bus interface version is exchanged by reading/writing the PCI config
space of the vGPU device.

Signed-off-by: Iouri Tarassov <iourit@linux.microsoft.com>

Author: Iouri Tarassov

MAINTAINERS

@@ -8190,6 +8190,12 @@ F:	Documentation/devicetree/bindings/mtd/ti,am654-hbmc.txt
 F:	drivers/mtd/hyperbus/
 F:	include/linux/mtd/hyperbus.h
 
+Hyper-V vGPU DRIVER
+M:	Iouri Tarassov <iourit@microsoft.com>
+L:	linux-hyperv@vger.kernel.org
+S:	Supported
+F:	drivers/hv/dxgkrnl/
+
 HYPERVISOR VIRTUAL CONSOLE DRIVER
 L:	linuxppc-dev@lists.ozlabs.org
 S:	Odd Fixes

drivers/hv/Kconfig

@@ -26,4 +26,6 @@ config HYPERV_BALLOON
 	help
 	  Select this option to enable Hyper-V Balloon driver.
 
+source "drivers/hv/dxgkrnl/Kconfig"
+
 endmenu

drivers/hv/Makefile

@@ -2,6 +2,7 @@
 obj-$(CONFIG_HYPERV)		+= hv_vmbus.o
 obj-$(CONFIG_HYPERV_UTILS)	+= hv_utils.o
 obj-$(CONFIG_HYPERV_BALLOON)	+= hv_balloon.o
+obj-$(CONFIG_DXGKRNL)		+= dxgkrnl/
 
 CFLAGS_hv_trace.o = -I$(src)
 CFLAGS_hv_balloon.o = -I$(src)

drivers/hv/dxgkrnl/Kconfig

@@ -0,0 +1,26 @@
+#
+# dxgkrnl configuration
+#
+
+config DXGKRNL
+	tristate "Microsoft Paravirtualized GPU support"
+	depends on HYPERV
+	depends on 64BIT || COMPILE_TEST
+	help
+	  This driver supports paravirtualized virtual compute devices, exposed
+	  by Microsoft Hyper-V when Linux is running inside of a virtual machine
+	  hosted by Windows. The virtual machines needs to be configured to use
+	  host compute adapters. The driver name is dxgkrnl.
+
+	  An example of such virtual machine is a  Windows Subsystem for
+	  Linux container. When such container is instantiated, the Windows host
+	  assigns compatible host GPU adapters to the container. The corresponding
+	  virtual GPU devices appear on the PCI bus in the container. These
+	  devices are enumerated and accessed by this driver.
+
+	  Communications with the driver are done by using the Microsoft libdxcore
+	  library, which translates the D3DKMT interface
+	  <https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/d3dkmthk/>
+	  to the driver IOCTLs. The virtual GPU devices are paravirtualized,
+	  which means that access to the hardware is done in the host. The driver
+	  communicates with the host using Hyper-V VM bus communication channels.

drivers/hv/dxgkrnl/Makefile

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for the Linux video drivers.
+
+obj-$(CONFIG_DXGKRNL)	+= dxgkrnl.o
+dxgkrnl-y		:= dxgmodule.o hmgr.o misc.o dxgadapter.o ioctl.o dxgvmbus.o dxgprocess.o