[PATCH v7-incomplete 1/3] PCI: Move PRESERVE_BOOT_CONFIG _DSM evaluation to pci_register_host_bridge()

Bjorn Helgaas
2024-04-21T19:09:29Z

From: Bjorn Helgaas <bhelgaas@google.com>

Move the PRESERVE_BOOT_CONFIG _DSM evaluation from acpi_pci_root_create()
to pci_register_host_bridge().

This will help unify the ACPI _DSM path and the DT-based
"linux,pci-probe-only" paths.

This should be safe because it happens earlier than it used to:

acpi_pci_root_create
pci_create_root_bus
pci_register_host_bridge
+ bridge->preserve_config = pci_preserve_config(bridge)
pci_acpi_preserve_config
+ acpi_evaluate_dsm_typed(DSM_PCI_PRESERVE_BOOT_CONFIG)
- acpi_evaluate_dsm_typed(DSM_PCI_PRESERVE_BOOT_CONFIG)

No functional change intended.
---
drivers/acpi/pci_root.c | 12 ------------
drivers/pci/pci-acpi.c | 22 ++++++++++++++++++++++
drivers/pci/pci.h | 5 +++++
drivers/pci/probe.c | 11 +++++++++++
4 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 58b89b8d950e..ddc2b3e89111 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -1008,7 +1008,6 @@ 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;
@@ -1050,17 +1049,6 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
if (!(root->osc_ext_control_set & OSC_CXL_ERROR_REPORTING_CONTROL))
host_bridge->native_cxl_error = 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_typed(ACPI_HANDLE(bus->bridge), &pci_acpi_dsm_guid, 1,
- DSM_PCI_PRESERVE_BOOT_CONFIG, NULL, ACPI_TYPE_INTEGER);
- if (obj && obj->integer.value == 0)
- host_bridge->preserve_config = 1;
- ACPI_FREE(obj);
-
acpi_dev_power_up_children_with_adr(device);

pci_scan_child_bus(bus);
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 004575091596..9cc447da9475 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -119,6 +119,28 @@ phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
return (phys_addr_t)mcfg_addr;
}

+bool pci_acpi_preserve_config(struct pci_host_bridge *host_bridge)
+{
+ if (ACPI_HANDLE(&host_bridge->dev)) {
+ union acpi_object *obj;
+
+ /*
+ * 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_typed(ACPI_HANDLE(&host_bridge->dev),
+ &pci_acpi_dsm_guid,
+ 1, DSM_PCI_PRESERVE_BOOT_CONFIG,
+ NULL, ACPI_TYPE_INTEGER);
+ if (obj && obj->integer.value == 0)
+ return true;
+ ACPI_FREE(obj);
+ }
+
+ return false;
+}
+
/* _HPX PCI Setting Record (Type 0); same as _HPP */
struct hpx_type0 {
u32 revision; /* Not present in _HPP */
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 17fed1846847..180d3907b543 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -734,6 +734,7 @@ static inline void pci_restore_aer_state(struct pci_dev *dev) { }
#endif

#ifdef CONFIG_ACPI
+bool pci_acpi_preserve_config(struct pci_host_bridge *bridge);
int pci_acpi_program_hp_params(struct pci_dev *dev);
extern const struct attribute_group pci_dev_acpi_attr_group;
void pci_set_acpi_fwnode(struct pci_dev *dev);
@@ -747,6 +748,10 @@ int acpi_pci_wakeup(struct pci_dev *dev, bool enable);
bool acpi_pci_need_resume(struct pci_dev *dev);
pci_power_t acpi_pci_choose_state(struct pci_dev *pdev);
#else
+static inline bool pci_acpi_preserve_config(struct pci_host_bridge *bridge)
+{
+ return false;
+}
static inline int pci_dev_acpi_reset(struct pci_dev *dev, bool probe)
{
return -ENOTTY;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1325fbae2f28..ee086d029450 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -889,6 +889,14 @@ static void pci_set_bus_msi_domain(struct pci_bus *bus)
dev_set_msi_domain(&bus->dev, d);
}

+static bool pci_preserve_config(struct pci_host_bridge *host_bridge)
+{
+ if (pci_acpi_preserve_config(host_bridge))
+ return true;
+
+ return false;
+}
+
static int pci_register_host_bridge(struct pci_host_bridge *bridge)
{
struct device *parent = bridge->dev.parent;
@@ -983,6 +991,9 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
if (nr_node_ids > 1 && pcibus_to_node(bus) == NUMA_NO_NODE)
dev_warn(&bus->dev, "Unknown NUMA node; performance will be reduced\n");

+ /* Check if the boot configuration by FW needs to be preserved */
+ bridge->preserve_config = pci_preserve_config(bridge);
+
/* Coalesce contiguous windows */
resource_list_for_each_entry_safe(window, n, &resources) {
if (list_is_last(&window->node, &resources))
--
2.34.1