UBUNTU: SAUCE: cxlflash: Verify problem state area is mapped before notifying shutdown

BugLink: http://bugs.launchpad.net/bugs/1605405

If an EEH or some other hard error occurs while the
adapter instance was being initialized, on the subsequent
shutdown of the device, the system could crash with:

[c000000f1da03b60] c0000000005eccfc pci_device_shutdown+0x6c/0x100
[c000000f1da03ba0] c0000000006d67d4 device_shutdown+0x1b4/0x2c0
[c000000f1da03c40] c0000000000ea30c kernel_restart_prepare+0x5c/0x80
[c000000f1da03c70] c0000000000ea48c kernel_restart+0x2c/0xc0
[c000000f1da03ce0] c0000000000ea970 SyS_reboot+0x1c0/0x2d0
[c000000f1da03e30] c000000000009204 system_call+0x38/0xb4

This crash is due to the AFU not being mapped when the shutdown
notification routine is called and is a regression that was inserted
recently with Commit 704c4b0d ("cxlflash: Shutdown notify support
for CXL Flash cards").

As a fix, shutdown notification should only occur when the AFU is mapped.

Fixes: 704c4b0d ("cxlflash: Shutdown notify support for CXL Flash cards")
Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/scsi/cxlflash/main.c

@@ -778,7 +778,7 @@ static void notify_shutdown(struct cxlflash_cfg *cfg, bool wait)
 {
 	struct afu *afu = cfg->afu;
 	struct device *dev = &cfg->dev->dev;
-	struct sisl_global_map __iomem *global = &afu->afu_map->global;
+	struct sisl_global_map __iomem *global;
 	struct dev_dependent_vals *ddv;
 	u64 reg, status;
 	int i, retry_cnt = 0;
@@ -787,6 +787,14 @@ static void notify_shutdown(struct cxlflash_cfg *cfg, bool wait)
 	if (!(ddv->flags & CXLFLASH_NOTIFY_SHUTDOWN))
 		return;
 
+	if (!afu || !afu->afu_map) {
+		dev_dbg(dev, "%s: The problem state area is not mapped\n",
+			__func__);
+		return;
+	}
+
+	global = &afu->afu_map->global;
+
 	/* Notify AFU */
 	for (i = 0; i < NUM_FC_PORTS; i++) {
 		reg = readq_be(&global->fc_regs[i][FC_CONFIG2 / 8]);