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

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>

1 files changed, 62 insertions, 4 deletions

diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index 7ef768dce944..5dc324ca4090 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -99,6 +99,62 @@ extern u32 megasas_readl(struct megasas_instance *instance,
 			 const volatile void __iomem *addr);
 
 /**
+ * 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;
+}
+
+/**
  * megasas_check_same_4gb_region -	check if allocation
  *					crosses same 4GB boundary or not
  * @instance -				adapter's soft instance
@@ -4693,10 +4749,12 @@ 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 */