scsi: megaraid_sas: Block PCI config space access from userspace during OCR

ANBZ: torvalds#721

commit 78409d4 upstream.

While an online controller reset(OCR) is in progress, there is short
duration where all access to controller's PCI config space from the host
needs to be blocked.  This is due to a hardware limitation of MegaRAID
controllers.

With this patch, driver will block all access to controller's config space
from userland applications by calling pci_cfg_access_lock() while OCR is in
progress and unlocking after controller comes back to ready state.

Added helper function which locks the config space before initiating OCR
and wait for controller to become READY.

Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Liu Song <liusong@linux.alibaba.com>
Reviewed-by: Xunlei Pang <xlpang@linux.alibaba.com>
Link: https://gitee.com/anolis/cloud-kernel/pulls/598

Author: shivasharan-s

drivers/scsi/megaraid/megaraid_sas.h

@@ -2570,4 +2570,7 @@ void megasas_free_fusion_context(struct megasas_instance *instance);
 void megasas_set_dma_settings(struct megasas_instance *instance,
 			      struct megasas_dcmd_frame *dcmd,
 			      dma_addr_t dma_addr, u32 dma_len);
+int megasas_adp_reset_wait_for_ready(struct megasas_instance *instance,
+				     bool do_adp_reset,
+				     int ocr_context);
 #endif				/*LSI_MEGARAID_SAS_H */

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -5303,13 +5303,15 @@ static int megasas_init_fw(struct megasas_instance *instance)
 	}
 
 	if (megasas_transition_to_ready(instance, 0)) {
+		dev_info(&instance->pdev->dev,
+			 "Failed to transition controller to ready from %s!\n",
+			 __func__);
 		if (instance->adapter_type != MFI_SERIES) {
 			status_reg = instance->instancet->read_fw_status_reg(
 					instance);
 			if (status_reg & MFI_RESET_ADAPTER) {
-				instance->instancet->adp_reset
-					(instance, instance->reg_set);
-				if (megasas_transition_to_ready(instance, 0))
+				if (megasas_adp_reset_wait_for_ready
+					(instance, true, 0) == FAILED)
 					goto fail_ready_state;
 			} else {
 				goto fail_ready_state;
@@ -5319,16 +5321,17 @@ static int megasas_init_fw(struct megasas_instance *instance)
 			instance->instancet->adp_reset
 				(instance, instance->reg_set);
 			atomic_set(&instance->fw_reset_no_pci_access, 0);
-			dev_info(&instance->pdev->dev,
-				 "FW restarted successfully from %s!\n",
-				 __func__);
 
 			/*waiting for about 30 second before retry*/
 			ssleep(30);
 
 			if (megasas_transition_to_ready(instance, 0))
 				goto fail_ready_state;
 		}
+
+		dev_info(&instance->pdev->dev,
+			 "FW restarted successfully from %s!\n",
+			 __func__);
 	}
 
 	megasas_init_ctrl_params(instance);

drivers/scsi/megaraid/megaraid_sas_fusion.c

@@ -4506,6 +4506,62 @@ int megasas_check_mpio_paths(struct megasas_instance *instance,
 	return retval;
 }
 
+/**
+ * megasas_adp_reset_wait_for_ready -	initiate chip reset and wait for
+ *					controller to come to ready state
+ * @instance -				adapter's soft state
+ * @do_adp_reset -			If true, do a chip reset
+ * @ocr_context -			If called from OCR context this will
+ *					be set to 1, else 0
+ *
+ * This function initates a chip reset followed by a wait for controller to
+ * transition to ready state.
+ * During this, driver will block all access to PCI config space from userspace
+ */
+int
+megasas_adp_reset_wait_for_ready(struct megasas_instance *instance,
+				 bool do_adp_reset,
+				 int ocr_context)
+{
+	int ret = FAILED;
+
+	/*
+	 * Block access to PCI config space from userspace
+	 * when diag reset is initiated from driver
+	 */
+	if (megasas_dbg_lvl & OCR_LOGS)
+		dev_info(&instance->pdev->dev,
+			 "Block access to PCI config space %s %d\n",
+			 __func__, __LINE__);
+
+	pci_cfg_access_lock(instance->pdev);
+
+	if (do_adp_reset) {
+		if (instance->instancet->adp_reset
+			(instance, instance->reg_set))
+			goto out;
+	}
+
+	/* Wait for FW to become ready */
+	if (megasas_transition_to_ready(instance, ocr_context)) {
+		dev_warn(&instance->pdev->dev,
+			 "Failed to transition controller to ready for scsi%d.\n",
+			 instance->host->host_no);
+		goto out;
+	}
+
+	ret = SUCCESS;
+out:
+	if (megasas_dbg_lvl & OCR_LOGS)
+		dev_info(&instance->pdev->dev,
+			 "Unlock access to PCI config space %s %d\n",
+			 __func__, __LINE__);
+
+	pci_cfg_access_unlock(instance->pdev);
+
+	return ret;
+}
+
 /* Core fusion reset function */
 int megasas_reset_fusion(struct Scsi_Host *shost, int reason)
 {
@@ -4646,10 +4702,12 @@ int megasas_reset_fusion(struct Scsi_Host *shost, int reason)
 
 		/* Now try to reset the chip */
 		for (i = 0; i < max_reset_tries; i++) {
-
-			if (do_adp_reset &&
-			    instance->instancet->adp_reset
-				(instance, instance->reg_set))
+			/*
+			 * Do adp reset and wait for
+			 * controller to transition to ready
+			 */
+			if (megasas_adp_reset_wait_for_ready(instance,
+				do_adp_reset, 1) == FAILED)
 				continue;
 
 			/* Wait for FW to become ready */