drm/amdgpu: introduce a stolen reserved buffer to protect specific buffer region (v2)

Some ASICs such as Yellow Carp needs to reserve a region of video memory
to avoid access from driver. So this patch is to introduce a stolen
reserved buffer to protect specific buffer region.

v2: free this buffer in amdgpu_ttm_fini.

Signed-off-by: Huang Rui <ray.huang@amd.com>
Acked-and-Tested-by: Aaron Liu <aaron.liu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c

@@ -785,3 +785,19 @@ uint64_t amdgpu_gmc_vram_cpu_pa(struct amdgpu_device *adev, struct amdgpu_bo *bo
 {
 	return amdgpu_bo_gpu_offset(bo) - adev->gmc.vram_start + adev->gmc.aper_base;
 }
+
+void amdgpu_gmc_get_reserved_allocation(struct amdgpu_device *adev)
+{
+	/* Some ASICs need to reserve a region of video memory to avoid access
+	 * from driver */
+	switch (adev->asic_type) {
+	case CHIP_YELLOW_CARP:
+		adev->mman.stolen_reserved_offset = 0x1ffb0000;
+		adev->mman.stolen_reserved_size = 64 * PAGE_SIZE;
+		break;
+	default:
+		adev->mman.stolen_reserved_offset = 0;
+		adev->mman.stolen_reserved_size = 0;
+		break;
+	}
+}

drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h

@@ -332,6 +332,7 @@ amdgpu_gmc_set_vm_fault_masks(struct amdgpu_device *adev, int hub_type,
 			      bool enable);
 
 void amdgpu_gmc_get_vbios_allocations(struct amdgpu_device *adev);
+void amdgpu_gmc_get_reserved_allocation(struct amdgpu_device *adev);
 
 void amdgpu_gmc_init_pdb0(struct amdgpu_device *adev);
 uint64_t amdgpu_gmc_vram_mc2pa(struct amdgpu_device *adev, uint64_t mc_addr);

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

@@ -1718,6 +1718,13 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
 				       NULL);
 	if (r)
 		return r;
+	r = amdgpu_bo_create_kernel_at(adev, adev->mman.stolen_reserved_offset,
+				       adev->mman.stolen_reserved_size,
+				       AMDGPU_GEM_DOMAIN_VRAM,
+				       &adev->mman.stolen_reserved_memory,
+				       NULL);
+	if (r)
+		return r;
 
 	DRM_INFO("amdgpu: %uM of VRAM memory ready\n",
 		 (unsigned) (adev->gmc.real_vram_size / (1024 * 1024)));
@@ -1787,6 +1794,9 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev)
 	amdgpu_bo_free_kernel(&adev->mman.stolen_extended_memory, NULL, NULL);
 	/* return the IP Discovery TMR memory back to VRAM */
 	amdgpu_bo_free_kernel(&adev->mman.discovery_memory, NULL, NULL);
+	if (adev->mman.stolen_reserved_size)
+		amdgpu_bo_free_kernel(&adev->mman.stolen_reserved_memory,
+				      NULL, NULL);
 	amdgpu_ttm_fw_reserve_vram_fini(adev);
 
 	amdgpu_vram_mgr_fini(adev);

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h

@@ -84,6 +84,10 @@ struct amdgpu_mman {
 	struct amdgpu_bo	*stolen_extended_memory;
 	bool			keep_stolen_vga_memory;
 
+	struct amdgpu_bo	*stolen_reserved_memory;
+	uint64_t		stolen_reserved_offset;
+	uint64_t		stolen_reserved_size;
+
 	/* discovery */
 	uint8_t				*discovery_bin;
 	uint32_t			discovery_tmr_size;

drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c

@@ -936,6 +936,7 @@ static int gmc_v10_0_sw_init(void *handle)
 		return r;
 
 	amdgpu_gmc_get_vbios_allocations(adev);
+	amdgpu_gmc_get_reserved_allocation(adev);
 
 	/* Memory manager */
 	r = amdgpu_bo_init(adev);