[PATCH v2 1/2] PCI/AER: Do not use APEI/HEST to disable AER services globally

[Alexandru Gagniuc <mr.nuke.me@gmail.com>]

As part of the ACPI Platform Error Interfaces (APEI), the HEST table
describes the meaning of errors sources. Although HEST is related to
ownership of AER, the gatekeeper for AER ownership is the _OSC method.

HEST can identify error sources as firmware-first with granularity
ranging from device-level to global. It's not uncommon for HEST to
say "all AER errors sent via of APEI are firmware-first" by setting
the firmware-first and global bits. It's still allowable to do this
and grant the OS AER control over part of the PCIe topology.

Because there is quite some flexibility in how HEST and _OSC can
interact, it is wrong to assume that global firmware-first implies
_OSC will never grant AER control. If we don't ask for control, we are
not going to get it, and we may have entire parts of the PCIe tree
that do not report errors. Thus, ask for AER ownership, regardless of
HEST.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
---
 drivers/acpi/pci_root.c  |  9 ++-------
 drivers/pci/pcie/aer.c   | 25 +------------------------
 include/linux/pci-acpi.h |  6 ------
 3 files changed, 3 insertions(+), 37 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 707aafc7c2aa..32b2053bb0fa 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -491,13 +491,8 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
 	if (IS_ENABLED(CONFIG_HOTPLUG_PCI_SHPC))
 		control |= OSC_PCI_SHPC_NATIVE_HP_CONTROL;
 
-	if (pci_aer_available()) {
-		if (aer_acpi_firmware_first())
-			dev_info(&device->dev,
-				 "PCIe AER handled by firmware\n");
-		else
-			control |= OSC_PCI_EXPRESS_AER_CONTROL;
-	}
+	if (pci_aer_available())
+		control |= OSC_PCI_EXPRESS_AER_CONTROL;
 
 	requested = control;
 	status = acpi_pci_osc_control_set(handle, &control,
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index f8fc2114ad39..d029979e61f6 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -313,29 +313,6 @@ int pcie_aer_get_firmware_first(struct pci_dev *dev)
 	return dev->__aer_firmware_first;
 }
 
-static bool aer_firmware_first;
-
-/**
- * aer_acpi_firmware_first - Check if APEI should control AER.
- */
-bool aer_acpi_firmware_first(void)
-{
-	static bool parsed = false;
-	struct aer_hest_parse_info info = {
-		.pci_dev	= NULL,	/* Check all PCIe devices */
-		.firmware_first	= 0,
-	};
-
-	if (pcie_ports_native)
-		return false;
-
-	if (!parsed) {
-		apei_hest_parse(aer_hest_parse, &info);
-		aer_firmware_first = info.firmware_first;
-		parsed = true;
-	}
-	return aer_firmware_first;
-}
 #endif
 
 #define	PCI_EXP_AER_FLAGS	(PCI_EXP_DEVCTL_CERE | PCI_EXP_DEVCTL_NFERE | \
@@ -1450,7 +1427,7 @@ static struct pcie_port_service_driver aerdriver = {
  */
 int __init pcie_aer_init(void)
 {
-	if (!pci_aer_available() || aer_acpi_firmware_first())
+	if (!pci_aer_available())
 		return -ENXIO;
 	return pcie_port_service_register(&aerdriver);
 }
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index 8082b612f561..2e9c0b973eba 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -116,10 +116,4 @@ static inline void acpi_pci_add_bus(struct pci_bus *bus) { }
 static inline void acpi_pci_remove_bus(struct pci_bus *bus) { }
 #endif	/* CONFIG_ACPI */
 
-#ifdef CONFIG_ACPI_APEI
-extern bool aer_acpi_firmware_first(void);
-#else
-static inline bool aer_acpi_firmware_first(void) { return false; }
-#endif
-
 #endif	/* _PCI_ACPI_H_ */
-- 
2.19.2