dev-amdgpu: Add PM4PP, VMID, Linux definitions

The PM4 packet processor is handling all non-HSA GPU packets such
as packets for (un)mapping HSA queues. This commit pulls many
Linux structs and defines out into their own files for clarity.
Finally, it implements the VMID related functions in AMDGPU device.

Change-Id: I5f0057209305404df58aff2c4cd07762d1a31690
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/53068
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/amdgpu/AMDGPU.py

@@ -85,6 +85,7 @@ class AMDGPUDevice(PciDevice):
     # The config script should not create a new cp here but rather assign the
     # same cp that is assigned to the Shader SimObject.
     cp = Param.GPUCommandProcessor(NULL, "Command Processor")
+    pm4_pkt_proc = Param.PM4PacketProcessor("PM4 Packet Processor")
     memory_manager = Param.AMDGPUMemoryManager("GPU Memory Manager")
     memories = VectorParam.AbstractMemory([], "All memories in the device")
     device_ih = Param.AMDGPUInterruptHandler("GPU Interrupt handler")
@@ -97,6 +98,11 @@ class SDMAEngine(DmaVirtDevice):
     gpu_device = Param.AMDGPUDevice(NULL, 'GPU Controller')
     walker = Param.VegaPagetableWalker("Page table walker")
 
+class PM4PacketProcessor(DmaVirtDevice):
+    type = 'PM4PacketProcessor'
+    cxx_header = "dev/amdgpu/pm4_packet_processor.hh"
+    cxx_class = 'gem5::PM4PacketProcessor'
+
 class AMDGPUMemoryManager(ClockedObject):
     type = 'AMDGPUMemoryManager'
     cxx_header = 'dev/amdgpu/memory_manager.hh'