PCI / PCIe / AER: Disable native AER service if BIOS has precedence

From: Rafael J. Wysocki<[email protected]>

There is a design issue related to PCIe AER and _OSC that the BIOS may be asked to grant control of the AER service even if some Hardware Error Source Table (HEST) entries contain information meaning that the BIOS really should control it. Namely, pcie_port_acpi_setup() calls pcie_aer_get_firmware_first() that determines whether or not the AER service should be controlled by the BIOS on the basis of the HEST information for the given PCIe port. The BIOS is asked to grant control of the AER service for a PCIe Root Complex if pcie_aer_get_firmware_first() returns 'false' for at least one root port in that complex, even if all of the other root ports' HEST entries have the FIRMWARE_FIRST flag set (and none of them has the GLOBAL flag set). However, if the AER service is controlled by the kernel, that may interfere with the BIOS' handling of the error sources having the FIRMWARE_FIRST flag. Moreover, there may be PCIe endpoints that have the FIRMWARE_FIRST flag set in HEST and are attached to the root ports in question, in which case it also may be unsafe to ask the BIOS for control of the AER service.

For this reason, introduce a function checking if there's at least one PCIe-related HEST entry with the FIRMWARE_FIRST flag set and disable the native AER service altogether if this function returns 'true'.

Signed-off-by Rafael J. Wysocki<[email protected]>

---
  drivers/pci/pcie/aer/aerdrv.c      |    2 +-
  drivers/pci/pcie/aer/aerdrv.h      |    3 +++
  drivers/pci/pcie/aer/aerdrv_acpi.c |   31 +++++++++++++++++++++++++++++++
  drivers/pci/pcie/portdrv_acpi.c    |    2 +-
  4 files changed, 36 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/pci/pcie/aer/aerdrv_acpi.c
===================================================================

drivers/pci/pcie/aer/aerdrv_acpi.c +3 -0

@@ -93,4 +93,35 @@ int pcie_aer_get_firmware_first(struct p
  		aer_set_firmware_first(dev);
  	return dev->__aer_firmware_first;
  }
+
+static bool aer_firmware_first;
+

drivers/pci/pcie/aer/aerdrv_acpi.c +18 -0

+	default:
+		return 0;
+	}
+}
+
+/**
+ * aer_acpi_firmware_first - Check if APEI should control AER.
+ */
+bool aer_acpi_firmware_first(void)
+{
+	static bool parsed = false;
+
+	if (!parsed) {
+		apei_hest_parse(aer_hest_parse_aff, NULL);
+		parsed = true;
+	}
+	return aer_firmware_first;
+}
  #endif

Index: linux-2.6/drivers/pci/pcie/aer/aerdrv.h
===================================================================

drivers/pci/pcie/aer/aerdrv.h +3 -0

@@ -132,6 +132,7 @@ static inline int aer_osc_setup(struct p
 
  #ifdef CONFIG_ACPI_APEI
  extern int pcie_aer_get_firmware_first(struct pci_dev *pci_dev);
+extern bool aer_acpi_firmware_first(void);
  #else
  static inline int pcie_aer_get_firmware_first(struct pci_dev *pci_dev)
  {

@@ -139,6 +140,8 @@ static inline int pcie_aer_get_firmware_
  		return pci_dev->__aer_firmware_first;
  	return 0;
  }
+
+static inline bool aer_acpi_firmware_first(void) { return false; }
  #endif
 
  static inline void pcie_aer_force_firmware_first(struct pci_dev *pci_dev,

Index: linux-2.6/drivers/pci/pcie/aer/aerdrv.c
===================================================================

drivers/pci/pcie/aer/aerdrv.c +1 -1

@@ -416,7 +416,7 @@ static void aer_error_resume(struct pci_
   */
  static int __init aer_service_init(void)
  {
-	if (!pci_aer_available())
+	if (!pci_aer_available() || aer_acpi_firmware_first())
  		return -ENXIO;
  	return pcie_port_service_register(&aerdriver);
  }

Index: linux-2.6/drivers/pci/pcie/portdrv_acpi.c
===================================================================

drivers/pci/pcie/portdrv_acpi.c +1 -2

@@ -49,7 +49,7 @@ int pcie_port_acpi_setup(struct pci_dev
  		| OSC_PCI_EXPRESS_PME_CONTROL;
 
  	if (pci_aer_available()) {
-		if (pcie_aer_get_firmware_first(port))
+		if (aer_acpi_firmware_first())
  			dev_dbg(&port->dev, "PCIe errors handled by BIOS.\n");
  		else
  			flags |= OSC_PCI_EXPRESS_AER_CONTROL;
--

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Quoted 48 lines · Rafael J. Wysocki

From: Rafael J. Wysocki<[email protected]>

There is a design issue related to PCIe AER and _OSC that the BIOS may be asked to grant control of the AER service even if some Hardware Error Source Table (HEST) entries contain information meaning that the BIOS really should control it. Namely, pcie_port_acpi_setup() calls pcie_aer_get_firmware_first() that determines whether or not the AER service should be controlled by the BIOS on the basis of the HEST information for the given PCIe port. The BIOS is asked to grant control of the AER service for a PCIe Root Complex if pcie_aer_get_firmware_first() returns 'false' for at least one root port in that complex, even if all of the other root ports' HEST entries have the FIRMWARE_FIRST flag set (and none of them has the GLOBAL flag set). However, if the AER service is controlled by the kernel, that may interfere with the BIOS' handling of the error sources having the FIRMWARE_FIRST flag. Moreover, there may be PCIe endpoints that have the FIRMWARE_FIRST flag set in HEST and are attached to the root ports in question, in which case it also may be unsafe to ask the BIOS for control of the AER service.

For this reason, introduce a function checking if there's at least one PCIe-related HEST entry with the FIRMWARE_FIRST flag set and disable the native AER service altogether if this function returns 'true'.

Signed-off-by Rafael J. Wysocki<[email protected]>

---
  drivers/pci/pcie/aer/aerdrv.c      |    2 +-
  drivers/pci/pcie/aer/aerdrv.h      |    3 +++
  drivers/pci/pcie/aer/aerdrv_acpi.c |   31 +++++++++++++++++++++++++++++++
  drivers/pci/pcie/portdrv_acpi.c    |    2 +-
  4 files changed, 36 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/pci/pcie/aer/aerdrv_acpi.c
===================================================================

drivers/pci/pcie/aer/aerdrv_acpi.c +7 -0

@@ -93,4 +93,35 @@ int pcie_aer_get_firmware_first(struct p
  		aer_set_firmware_first(dev);
  	return dev->__aer_firmware_first;
  }
+
+static bool aer_firmware_first;
+
+static int aer_hest_parse_aff(struct acpi_hest_header *hest_hdr, void *data)
+{
+	if (aer_firmware_first)
+		return 0;

drivers/pci/pcie/aer/aerdrv_acpi.c int pcie_aer_get_firmware_first(struct p · line 108

Quoted 6 lines

drivers/pci/pcie/aer/aerdrv_acpi.c +6 -0

+
+	switch (hest_hdr->type) {
+	case ACPI_HEST_TYPE_AER_ROOT_PORT:
+	case ACPI_HEST_TYPE_AER_ENDPOINT:
+	case ACPI_HEST_TYPE_AER_BRIDGE:
+		aer_firmware_first = !!(p->flags&  ACPI_HEST_FIRMWARE_FIRST);

Where "p" comes from ? Maybe it points to "struct acpi_hest_aer_common *p;"

Quoted 21 lines · Chen Gong

Quoted 20 lines · Rafael J. Wysocki

From: Rafael J. Wysocki<[email protected]>

There is a design issue related to PCIe AER and _OSC that the BIOS may be asked to grant control of the AER service even if some Hardware Error Source Table (HEST) entries contain information meaning that the BIOS really should control it. Namely, pcie_port_acpi_setup() calls pcie_aer_get_firmware_first() that determines whether or not the AER service should be controlled by the BIOS on the basis of the HEST information for the given PCIe port. The BIOS is asked to grant control of the AER service for a PCIe Root Complex if pcie_aer_get_firmware_first() returns 'false' for at least one root port in that complex, even if all of the other root ports' HEST entries have the FIRMWARE_FIRST flag set (and none of them has the GLOBAL flag set). However, if the AER service is controlled by the kernel, that may interfere with the BIOS' handling of the error sources having the FIRMWARE_FIRST flag. Moreover, there may be PCIe endpoints that have the FIRMWARE_FIRST flag set in HEST and are attached to the root ports in question, in which case it also may be unsafe to ask the BIOS for control of the AER service.

Quoted 4 lines

Quoted 4 lines

For this reason, introduce a function checking if there's at least one PCIe-related HEST entry with the FIRMWARE_FIRST flag set and disable the native AER service altogether if this function returns 'true'.

Hi, Rafael,

Quoted 5 lines · Rafael J. Wysocki

drivers/pci/pcie/portdrv_acpi.c +0 -0

@@ -49,7 +49,7 @@ int pcie_port_acpi_setup(struct pci_dev 
 		| OSC_PCI_EXPRESS_PME_CONTROL;
 

drivers/pci/pcie/portdrv_acpi.c int pcie_port_acpi_setup(struct pci_dev · line 55

Quoted 6 lines

drivers/pci/pcie/portdrv_acpi.c +1 -1

 	if (pci_aer_available()) {
-		if (pcie_aer_get_firmware_first(port))
+		if (aer_acpi_firmware_first())
 			dev_dbg(&port->dev, "PCIe errors handled by BIOS.\n");
 		else
 			flags |= OSC_PCI_EXPRESS_AER_CONTROL;

The original per-device firmware_first is overridden by the new global firmware_first? If it is, why keep the original per-device firmware_first?