drm/amdgpu: add debugfs support for VM pagetable per client

Add a debugfs file under the client directory which shares
the root page table base address of the VM.

This address could be used to dump the pagetable for debug
memory issues.

Signed-off-by: Sunil Khatri <[e-mail]>
Reviewed-by: Christian König <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Christian König <[e-mail]>

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

···
 	return 0;
 }
 
+static int amdgpu_pt_info_read(struct seq_file *m, void *unused)
+{
+	struct drm_file *file;
+	struct amdgpu_fpriv *fpriv;
+	struct amdgpu_bo *root_bo;
+	int r;
+
+	file = m->private;
+	if (!file)
+		return -EINVAL;
+
+	fpriv = file->driver_priv;
+	if (!fpriv && !fpriv->vm.root.bo)
+		return -ENODEV;
+
+	root_bo = amdgpu_bo_ref(fpriv->vm.root.bo);
+	r = amdgpu_bo_reserve(root_bo, true);
+	if (r) {
+		amdgpu_bo_unref(&root_bo);
+		return -EINVAL;
+	}
+
+	seq_printf(m, "gpu_address: 0x%llx\n", amdgpu_bo_gpu_offset(fpriv->vm.root.bo));
+
+	amdgpu_bo_unreserve(root_bo);
+	amdgpu_bo_unref(&root_bo);
+
+	return 0;
+}
+
+static int amdgpu_pt_info_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, amdgpu_pt_info_read, inode->i_private);
+}
+
+static const struct file_operations amdgpu_pt_info_fops = {
+	.owner = THIS_MODULE,
+	.open = amdgpu_pt_info_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+void amdgpu_debugfs_vm_init(struct drm_file *file)
+{
+	debugfs_create_file("vm_pagetable_info", 0444, file->debugfs_client, file,
+			    &amdgpu_pt_info_fops);
+}
+
 #else
 int amdgpu_debugfs_init(struct amdgpu_device *adev)
 {
···
 int amdgpu_debugfs_regs_init(struct amdgpu_device *adev)
 {
 	return 0;
+}
+void amdgpu_debugfs_vm_init(struct drm_file *file)
+{
 }
 #endif

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

···
 void amdgpu_debugfs_firmware_init(struct amdgpu_device *adev);
 void amdgpu_debugfs_gem_init(struct amdgpu_device *adev);
 void amdgpu_debugfs_mes_event_log_init(struct amdgpu_device *adev);
+void amdgpu_debugfs_vm_init(struct drm_file *file);
 

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

···
 	if (r)
 		goto error_pasid;
 
+	amdgpu_debugfs_vm_init(file_priv);
+
 	r = amdgpu_vm_init(adev, &fpriv->vm, fpriv->xcp_id);
 	if (r)
 		goto error_pasid;