PCI/DPC: Fix print AER status in DPC event handling

Previously dpc_handler() called aer_get_device_error_info() without
initializing info->severity, so aer_get_device_error_info() relied on
uninitialized data.

Add dpc_get_aer_uncorrect_severity() to read the port's AER status, mask,
and severity registers and set info->severity.

Also, clear the port's AER fatal error status bits.

Fixes: 8aefa9b0d9 ("PCI/DPC: Print AER status in DPC event handling")
Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Cc: stable@vger.kernel.org	# v4.19+

drivers/pci/pcie/dpc.c

@@ -202,6 +202,28 @@ static void dpc_process_rp_pio_error(struct dpc_dev *dpc)
 	pci_write_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_STATUS, status);
 }
 
+static int dpc_get_aer_uncorrect_severity(struct pci_dev *dev,
+					  struct aer_err_info *info)
+{
+	int pos = dev->aer_cap;
+	u32 status, mask, sev;
+
+	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, &status);
+	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_MASK, &mask);
+	status &= ~mask;
+	if (!status)
+		return 0;
+
+	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_SEVER, &sev);
+	status &= sev;
+	if (status)
+		info->severity = AER_FATAL;
+	else
+		info->severity = AER_NONFATAL;
+
+	return 1;
+}
+
 static irqreturn_t dpc_handler(int irq, void *context)
 {
 	struct aer_err_info info;
@@ -229,9 +251,12 @@ static irqreturn_t dpc_handler(int irq, void *context)
 	/* show RP PIO error detail information */
 	if (dpc->rp_extensions && reason == 3 && ext_reason == 0)
 		dpc_process_rp_pio_error(dpc);
-	else if (reason == 0 && aer_get_device_error_info(pdev, &info)) {
+	else if (reason == 0 &&
+		 dpc_get_aer_uncorrect_severity(pdev, &info) &&
+		 aer_get_device_error_info(pdev, &info)) {
 		aer_print_error(pdev, &info);
 		pci_cleanup_aer_uncorrect_error_status(pdev);
+		pci_aer_clear_fatal_status(pdev);
 	}
 
 	/* We configure DPC so it only triggers on ERR_FATAL */