hw/acpi/pcihp: Remove root arg in acpi_pcihp_init

Let pass the root bus to ich9 and piix4 through a property link
instead of through an argument passed to acpi_pcihp_init().

Also make sure the root bus is set at the entry of acpi_pcihp_init().

The rationale of that change is to be consistent with the forecoming ARM
implementation where the machine passes the root bus (steming from GPEX)
to the GED device through a link property.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Suggested-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20250714080639.2525563-28-eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

5 files changed, 14 insertions, 6 deletions

diff --git a/hw/acpi/acpi-pci-hotplug-stub.c b/hw/acpi/acpi-pci-hotplug-stub.c
index b7bc6e4..d58ea72 100644
--- a/hw/acpi/acpi-pci-hotplug-stub.c
+++ b/hw/acpi/acpi-pci-hotplug-stub.c
@@ -4,7 +4,7 @@
 
 const VMStateDescription vmstate_acpi_pcihp_pci_status;
 
-void acpi_pcihp_init(Object *owner, AcpiPciHpState *s, PCIBus *root_bus,
+void acpi_pcihp_init(Object *owner, AcpiPciHpState *s,
                      MemoryRegion *address_space_io, uint16_t io_base)
 {
 }
diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
index 967b674..2b3b493 100644
--- a/hw/acpi/ich9.c
+++ b/hw/acpi/ich9.c
@@ -322,9 +322,10 @@ void ich9_pm_init(PCIDevice *lpc_pci, ICH9LPCPMRegs *pm, qemu_irq sci_irq)
     }
 
     if (pm->acpi_pci_hotplug.use_acpi_hotplug_bridge) {
+        object_property_set_link(OBJECT(lpc_pci), "bus",
+                                 OBJECT(pci_get_bus(lpc_pci)), &error_abort);
         acpi_pcihp_init(OBJECT(lpc_pci),
                         &pm->acpi_pci_hotplug,
-                        pci_get_bus(lpc_pci),
                         pci_address_space_io(lpc_pci),
                         ACPI_PCIHP_ADDR_ICH9);
 
@@ -428,6 +429,10 @@ void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs *pm)
 
     object_property_add_uint32_ptr(obj, ACPI_PM_PROP_PM_IO_BASE,
                                    &pm->pm_io_base, OBJ_PROP_FLAG_READ);
+    object_property_add_link(obj, "bus", TYPE_PCI_BUS,
+                             (Object **)&pm->acpi_pci_hotplug.root,
+                             object_property_allow_set_link,
+                             OBJ_PROP_LINK_STRONG);
     object_property_add(obj, ACPI_PM_PROP_GPE0_BLK, "uint32",
                         ich9_pm_get_gpe0_blk,
                         NULL, NULL, pm);
diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index f1594e6..4922bbc 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -493,13 +493,13 @@ static const MemoryRegionOps acpi_pcihp_io_ops = {
     },
 };
 
-void acpi_pcihp_init(Object *owner, AcpiPciHpState *s, PCIBus *root_bus,
+void acpi_pcihp_init(Object *owner, AcpiPciHpState *s,
                      MemoryRegion *io, uint16_t io_base)
 {
     s->io_len = ACPI_PCIHP_SIZE;
     s->io_base = io_base;
 
-    s->root = root_bus;
+    assert(s->root);
 
     memory_region_init_io(&s->io, owner, &acpi_pcihp_io_ops, s,
                           "acpi-pci-hotplug", s->io_len);
diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index d98b80d..7a18f18 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -567,7 +567,8 @@ static void piix4_acpi_system_hot_add_init(MemoryRegion *parent,
 
     if (s->acpi_pci_hotplug.use_acpi_hotplug_bridge ||
         s->acpi_pci_hotplug.use_acpi_root_pci_hotplug) {
-        acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent,
+        object_property_set_link(OBJECT(s), "bus", OBJECT(bus), &error_abort);
+        acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, parent,
                         ACPI_PCIHP_ADDR_PIIX4);
         qbus_set_hotplug_handler(BUS(pci_get_bus(PCI_DEVICE(s))), OBJECT(s));
     }
@@ -611,6 +612,8 @@ static const Property piix4_pm_properties[] = {
                      acpi_pci_hotplug.use_acpi_hotplug_bridge, true),
     DEFINE_PROP_BOOL(ACPI_PM_PROP_ACPI_PCI_ROOTHP, PIIX4PMState,
                      acpi_pci_hotplug.use_acpi_root_pci_hotplug, true),
+    DEFINE_PROP_LINK("bus", PIIX4PMState, acpi_pci_hotplug.root,
+                     TYPE_PCI_BUS, PCIBus *),
     DEFINE_PROP_BOOL("memory-hotplug-support", PIIX4PMState,
                      acpi_memory_hotplug.is_enabled, true),
     DEFINE_PROP_BOOL("smm-compat", PIIX4PMState, smm_compat, false),
diff --git a/include/hw/acpi/pcihp.h b/include/hw/acpi/pcihp.h
index 9ff5486..ca6a258 100644
--- a/include/hw/acpi/pcihp.h
+++ b/include/hw/acpi/pcihp.h
@@ -62,7 +62,7 @@ typedef struct AcpiPciHpState {
     bool use_acpi_root_pci_hotplug;
 } AcpiPciHpState;
 
-void acpi_pcihp_init(Object *owner, AcpiPciHpState *, PCIBus *root,
+void acpi_pcihp_init(Object *owner, AcpiPciHpState *,
                      MemoryRegion *io, uint16_t io_base);
 
 bool acpi_pcihp_is_hotpluggable_bus(AcpiPciHpState *s, BusState *bus);