From 5352a44a561d708f1a975a90f5ce16a054fe265c Mon Sep 17 00:00:00 2001
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Wed, 23 May 2018 17:24:08 -0500
Subject: [PATCH] PCI: pciehp: Make pciehp_is_native() stricter
Git-commit: 5352a44a561d708f1a975a90f5ce16a054fe265c
Patch-mainline: v4.18
References: FATE#326302

Previously pciehp_is_native() returned true for any PCI device in a
hierarchy where _OSC says we can use pciehp.  This is incorrect because
bridges without PCI_EXP_SLTCAP_HPC capability should be managed by acpiphp
instead.

Improve pciehp_is_native() to return true only when PCI_EXP_SLTCAP_HPC is
set and the pciehp driver is present.  In any other case return false
to let acpiphp handle those.

Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[bhelgaas: remove NULL pointer check]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/pci/pci-acpi.c      |   26 ++++++++++++++------------
 drivers/pci/pcie/portdrv.h  |    2 --
 include/linux/pci.h         |    2 ++
 include/linux/pci_hotplug.h |    4 ++--
 4 files changed, 18 insertions(+), 16 deletions(-)

--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -370,26 +370,28 @@ EXPORT_SYMBOL_GPL(pci_get_hp_params);
 
 /**
  * pciehp_is_native - Check whether a hotplug port is handled by the OS
- * @pdev: Hotplug port to check
+ * @bridge: Hotplug port to check
  *
- * Walk up from @pdev to the host bridge, obtain its cached _OSC Control Field
- * and return the value of the "PCI Express Native Hot Plug control" bit.
- * On failure to obtain the _OSC Control Field return %false.
+ * Returns true if the given @bridge is handled by the native PCIe hotplug
+ * driver.
  */
-bool pciehp_is_native(struct pci_dev *pdev)
+bool pciehp_is_native(struct pci_dev *bridge)
 {
-	struct acpi_pci_root *root;
-	acpi_handle handle;
+	const struct pci_host_bridge *host;
+	u32 slot_cap;
 
-	handle = acpi_find_root_bridge_handle(pdev);
-	if (!handle)
+	if (!IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
 		return false;
 
-	root = acpi_pci_find_root(handle);
-	if (!root)
+	pcie_capability_read_dword(bridge, PCI_EXP_SLTCAP, &slot_cap);
+	if (!(slot_cap & PCI_EXP_SLTCAP_HPC))
 		return false;
 
-	return root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL;
+	if (pcie_ports_native)
+		return true;
+
+	host = pci_find_host_bridge(bridge->bus);
+	return host->native_pcie_hotplug;
 }
 
 /**
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1465,9 +1465,11 @@ static inline int pci_irqd_intx_xlate(st
 
 #ifdef CONFIG_PCIEPORTBUS
 extern bool pcie_ports_disabled;
+extern bool pcie_ports_native;
 extern bool pcie_ports_auto;
 #else
 #define pcie_ports_disabled	true
+#define pcie_ports_native	false
 #define pcie_ports_auto		false
 #endif
 
--- a/include/linux/pci_hotplug.h
+++ b/include/linux/pci_hotplug.h
@@ -176,7 +176,7 @@ struct hotplug_params {
 #ifdef CONFIG_ACPI
 #include <linux/acpi.h>
 int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp);
-bool pciehp_is_native(struct pci_dev *pdev);
+bool pciehp_is_native(struct pci_dev *bridge);
 int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags);
 int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle);
 int acpi_pci_detect_ejectable(acpi_handle handle);
@@ -186,6 +186,6 @@ static inline int pci_get_hp_params(stru
 {
 	return -ENODEV;
 }
-static inline bool pciehp_is_native(struct pci_dev *pdev) { return true; }
+static inline bool pciehp_is_native(struct pci_dev *bridge) { return true; }
 #endif
 #endif
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -11,8 +11,6 @@
 
 #include <linux/compiler.h>
 
-extern bool pcie_ports_native;
-
 /* Service Type */
 #define PCIE_PORT_SERVICE_PME_SHIFT	0	/* Power Management Event */
 #define PCIE_PORT_SERVICE_PME		(1 << PCIE_PORT_SERVICE_PME_SHIFT)