drm/amdgpu: Add PASID management

Allows assigning a PASID to a VM for identifying VMs involved in page
faults. The global PASID manager is also exported in the KFD
interface so that AMDGPU and KFD can share the PASID space.

PASIDs of different sizes can be requested. On APUs, the PASID size
is deterined by the capabilities of the IOMMU. So KFD must be able
to allocate PASIDs in a smaller range.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/include/kgd_kfd_interface.h

@@ -112,6 +112,9 @@ struct tile_config {
  *
  * @get_max_engine_clock_in_mhz: Retrieves maximum GPU clock in MHz
  *
+ * @alloc_pasid: Allocate a PASID
+ * @free_pasid: Free a PASID
+ *
  * @program_sh_mem_settings: A function that should initiate the memory
  * properties such as main aperture memory type (cache / non cached) and
  * secondary aperture base address, size and memory type.
@@ -160,6 +163,9 @@ struct kfd2kgd_calls {
 
 	uint32_t (*get_max_engine_clock_in_mhz)(struct kgd_dev *kgd);
 
+	int (*alloc_pasid)(unsigned int bits);
+	void (*free_pasid)(unsigned int pasid);
+
 	/* Register access functions */
 	void (*program_sh_mem_settings)(struct kgd_dev *kgd, uint32_t vmid,
 			uint32_t sh_mem_config,	uint32_t sh_mem_ape1_base,