[PATCH] PCI/AER: Cleanup AER error status registers on probing devices

[Taku Izumi <izumi.taku@jp.fujitsu.com>]

AER uncorrectable or correctable error might be recorded
when power on devices. These errors can be ignored, so
BIOS usually clean up these registers ahead of OS's scanning
devices.
However, in case of hot-plug PCIe devices, BIOS can't care.
Currently OS don't clean up AER error status registers on probing
devices, ignorable AER errors recorded when power-on remains.
This causes false-positive.

This patch address this problem by cleaning up
AER error status registers on probing devices.

Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
---
 drivers/pci/pcie/aer/aerdrv_core.c | 26 ++++++++++++++++++++++++++
 drivers/pci/probe.c                |  5 +++++
 include/linux/aer.h                |  5 +++++
 3 files changed, 36 insertions(+)

diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
index 9803e3d..9857cc4 100644
--- a/drivers/pci/pcie/aer/aerdrv_core.c
+++ b/drivers/pci/pcie/aer/aerdrv_core.c
@@ -74,6 +74,32 @@ int pci_cleanup_aer_uncorrect_error_status(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_cleanup_aer_uncorrect_error_status);
 
+int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
+{
+	int pos;
+	u32 status;
+	int port_type;
+
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
+	if (!pos)
+		return -EIO;
+
+	port_type = pci_pcie_type(dev);
+	if (port_type == PCI_EXP_TYPE_ROOT_PORT) {
+		pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, &status);
+		pci_write_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, status);
+	}
+
+	pci_read_config_dword(dev, pos + PCI_ERR_COR_STATUS, &status);
+	pci_write_config_dword(dev, pos + PCI_ERR_COR_STATUS, status);
+
+	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, &status);
+	pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, status);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_cleanup_aer_error_status_regs);
+
 /**
  * add_error_device - list device to be handled
  * @e_info: pointer to error info
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index cefd636..d660db7 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/cpumask.h>
 #include <linux/pci-aspm.h>
+#include <linux/aer.h>
 #include <asm-generic/pci-bridge.h>
 #include "pci.h"
 
@@ -1542,6 +1543,10 @@ static void pci_init_capabilities(struct pci_dev *dev)
 
 	/* Enable ACS P2P upstream forwarding */
 	pci_enable_acs(dev);
+
+	/* Cleanup AER error status registerts */
+	if (pci_is_pcie(dev))
+		pci_cleanup_aer_error_status_regs(dev);
 }
 
 void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
diff --git a/include/linux/aer.h b/include/linux/aer.h
index 4fef65e..744b997 100644
--- a/include/linux/aer.h
+++ b/include/linux/aer.h
@@ -42,6 +42,7 @@ struct aer_capability_regs {
 int pci_enable_pcie_error_reporting(struct pci_dev *dev);
 int pci_disable_pcie_error_reporting(struct pci_dev *dev);
 int pci_cleanup_aer_uncorrect_error_status(struct pci_dev *dev);
+int pci_cleanup_aer_error_status_regs(struct pci_dev *dev);
 #else
 static inline int pci_enable_pcie_error_reporting(struct pci_dev *dev)
 {
@@ -55,6 +56,10 @@ static inline int pci_cleanup_aer_uncorrect_error_status(struct pci_dev *dev)
 {
 	return -EINVAL;
 }
+static inline int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
+{
+	return -EINVAL;
+}
 #endif
 
 void cper_print_aer(struct pci_dev *dev, int cper_severity,
-- 
1.8.3.1