PCI/ACPI: Evaluate PCI Boot Configuration _DSM

ANBZ: #43 commit a78cf96 upstream Evaluate _DSM Function #5, the "PCI Boot Configuration" function. If the result is 0, the OS should preserve any resource assignments made by the firmware. [ Guanjun: fix conflicts in include/linux/pci.h ] Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Benjamin Herrenschmidt <[email protected]> [bhelgaas: commit log] Signed-off-by: Bjorn Helgaas <[email protected]> Signed-off-by: Guanjun <[email protected]> Reviewed-by: Zelin Deng <[email protected]>
alibaba · Dec 7, 2021 · 849bfd8 · 849bfd8
1 parent 2210712
commit 849bfd8
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Showing 3 changed files with 18 additions and 3 deletions.
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
@@ -897,6 +897,7 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
 	int node = acpi_get_node(device->handle);
 	struct pci_bus *bus;
 	struct pci_host_bridge *host_bridge;
+	union acpi_object *obj;
 
 	info->root = root;
 	info->bridge = device;
@@ -935,6 +936,17 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
 	if (!(root->osc_control_set & OSC_PCI_EXPRESS_DPC_CONTROL))
 		host_bridge->native_dpc = 0;
 
+	/*
+	 * Evaluate the "PCI Boot Configuration" _DSM Function.  If it
+	 * exists and returns 0, we must preserve any PCI resource
+	 * assignments made by firmware for this host bridge.
+	 */
+	obj = acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), &pci_acpi_dsm_guid, 1,
+	                        IGNORE_PCI_BOOT_CONFIG_DSM, NULL);
+	if (obj && obj->type == ACPI_TYPE_INTEGER && obj->integer.value == 0)
+		host_bridge->preserve_config = 1;
+	ACPI_FREE(obj);
+
 	pci_scan_child_bus(bus);
 	pci_set_host_bridge_release(host_bridge, acpi_pci_root_release_info,
 				    info);

diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
@@ -107,9 +107,10 @@ static inline void acpiphp_check_host_bridge(struct acpi_device *adev) { }
 #endif
 
 extern const guid_t pci_acpi_dsm_guid;
-#define DEVICE_LABEL_DSM	0x07
-#define RESET_DELAY_DSM		0x08
-#define FUNCTION_DELAY_DSM	0x09
+#define IGNORE_PCI_BOOT_CONFIG_DSM	0x05
+#define DEVICE_LABEL_DSM		0x07
+#define RESET_DELAY_DSM			0x08
+#define FUNCTION_DELAY_DSM		0x09
 
 #ifdef CONFIG_PCIE_EDR
 void pci_acpi_add_edr_notifier(struct pci_dev *pdev);

diff --git a/include/linux/pci.h b/include/linux/pci.h
@@ -493,6 +493,8 @@ struct pci_host_bridge {
 	unsigned int	native_pme:1;		/* OS may use PCIe PME */
 	unsigned int	native_ltr:1;		/* OS may use PCIe LTR */
 	unsigned int	native_dpc:1;		/* OS may use PCIe DPC */
+	unsigned int	preserve_config:1;	/* Preserve FW resource setup */
+
 	/* Resource alignment requirements */
 	resource_size_t (*align_resource)(struct pci_dev *dev,
 			const struct resource *res,