disp: msm: dsi: avoid debugfs HW access based on HW ownership

Add VM ownership checks before accessing the HW through the debugfs
path in dsi display/ctrl modules to avoid illegal access.

Change-Id: Ia6e2ab0ef60d0f11e5945a63885d939db2ef78b0
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>

msm/dsi/dsi_display.c

@@ -1448,6 +1448,14 @@ static ssize_t debugfs_misr_setup(struct file *file,
 	display->misr_frame_count = frame_count;
 
 	mutex_lock(&display->display_lock);
+
+	if (!display->hw_ownership) {
+		DSI_DEBUG("[%s] op not supported due to HW unavailability\n",
+				display->name);
+		rc = -EOPNOTSUPP;
+		goto unlock;
+	}
+
 	rc = dsi_display_clk_ctrl(display->dsi_clk_handle,
 			DSI_CORE_CLK, DSI_CLK_ON);
 	if (rc) {
@@ -1499,6 +1507,14 @@ static ssize_t debugfs_misr_read(struct file *file,
 		return -ENOMEM;
 
 	mutex_lock(&display->display_lock);
+
+	if (!display->hw_ownership) {
+		DSI_DEBUG("[%s] op not supported due to HW unavailability\n",
+				display->name);
+		rc = -EOPNOTSUPP;
+		goto error;
+	}
+
 	rc = dsi_display_clk_ctrl(display->dsi_clk_handle,
 			DSI_CORE_CLK, DSI_CLK_ON);
 	if (rc) {
@@ -1596,6 +1612,15 @@ static ssize_t debugfs_esd_trigger_check(struct file *file,
 
 	display->esd_trigger = esd_trigger;
 
+	mutex_lock(&display->display_lock);
+
+	if (!display->hw_ownership) {
+		DSI_DEBUG("[%s] op not supported due to HW unavailability\n",
+				display->name);
+		rc = -EOPNOTSUPP;
+		goto unlock;
+	}
+
 	if (display->esd_trigger) {
 		DSI_INFO("ESD attack triggered by user\n");
 		rc = dsi_panel_trigger_esd_attack(display->panel,
@@ -1607,6 +1632,8 @@ static ssize_t debugfs_esd_trigger_check(struct file *file,
 	}
 
 	rc = len;
+unlock:
+	mutex_unlock(&display->display_lock);
 error:
 	kfree(buf);
 	return rc;
@@ -4156,10 +4183,13 @@ static int dsi_display_res_init(struct dsi_display *display)
 	 * In trusted vm, the connectors will not be enabled
 	 * until the HW resources are assigned and accepted.
 	 */
-	if (display->trusted_vm_env)
+	if (display->trusted_vm_env) {
 		display->is_active = false;
-	else
+		display->hw_ownership = false;
+	} else {
 		display->is_active = true;
+		display->hw_ownership = true;
+	}
 
 	return 0;
 error_ctrl_put:
@@ -4168,6 +4198,7 @@ error_ctrl_put:
 		dsi_ctrl_put(ctrl->ctrl);
 		dsi_phy_put(ctrl->phy);
 	}
+
 	return rc;
 }
 
@@ -5379,19 +5410,33 @@ end:
 
 static int dsi_display_pre_release(void *data)
 {
+	struct dsi_display *display;
+
 	if (!data)
 		return -EINVAL;
 
-	dsi_display_ctrl_irq_update((struct dsi_display *)data, false);
+	display = (struct dsi_display *)data;
+	mutex_lock(&display->display_lock);
+	display->hw_ownership = false;
+	mutex_unlock(&display->display_lock);
+
+	dsi_display_ctrl_irq_update(display, false);
 
 	return 0;
 }
 
 static int dsi_display_pre_acquire(void *data)
 {
+	struct dsi_display *display;
+
 	if (!data)
 		return -EINVAL;
 
+	display = (struct dsi_display *)data;
+	mutex_lock(&display->display_lock);
+	display->hw_ownership = true;
+	mutex_unlock(&display->display_lock);
+
 	dsi_display_ctrl_irq_update((struct dsi_display *)data, true);
 
 	return 0;
@@ -7666,6 +7711,7 @@ int dsi_display_prepare(struct dsi_display *display)
 	SDE_EVT32(SDE_EVTLOG_FUNC_ENTRY);
 	mutex_lock(&display->display_lock);
 
+	display->hw_ownership = true;
 	mode = display->panel->cur_mode;
 
 	dsi_display_set_ctrl_esd_check_flag(display, false);
@@ -8573,6 +8619,7 @@ int dsi_display_unprepare(struct dsi_display *display)
 			DSI_ERR("[%s] panel post-unprepare failed, rc=%d\n",
 			       display->name, rc);
 	}
+	display->hw_ownership = false;
 
 	mutex_unlock(&display->display_lock);
 

msm/dsi/dsi_display.h

@@ -187,6 +187,7 @@ struct dsi_display_ext_bridge {
  * @is_active:        status of the display
  * @trusted_vm_env:   Set to true, it the executing VM is Trusted VM.
  *                    Set to false, otherwise.
+ * @hw_ownership:     Indicates if VM owns the hardware resources.
  * @tx_cmd_buf_ndx:   Index to the DSI debugfs TX CMD buffer.
  * @cmd_set:	      Debugfs TX cmd set.
  * @enabled:	      Boolean to indicate display enabled.
@@ -287,6 +288,7 @@ struct dsi_display {
 	bool is_active;
 
 	bool trusted_vm_env;
+	bool hw_ownership;
 
 	int tx_cmd_buf_ndx;
 	struct dsi_panel_cmd_set cmd_set;