[PATCH v6 09/12] piix4: don't reserve hw resources when hotplug is off globally

[Ani Sinha]

When acpi hotplug is turned off for both root pci bus as well as for pci
bridges, we should not generate the related ACPI code for DSDT table or
initialize related hw ports or reserve hw resources. This change makes
sure all those operations are turned off in the case ACPI pci hotplug is
off globally.

In this change, we also make sure ACPI code for the PCNT method are only
added when bsel is enabled for the corresponding pci bus or bridge hotplug
is turned on.

As q35 machines do not use bsel for it's pci buses at this point in time, this
change affects DSDT acpi table for q35 machines as well. Therefore, we will
also need to commit the updated golden master DSDT table acpi binary blobs as
well. This is done in the following commit. Without the updated table blobs,
the unit tests would fail with this patch.

Signed-off-by: Ani Sinha <ani@anisinha.ca>
---
 hw/acpi/piix4.c      |  6 ++++--
 hw/i386/acpi-build.c | 25 ++++++++++++++++++-------
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index e6163bb6ce..b70b1f98af 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -596,8 +596,10 @@ static void piix4_acpi_system_hot_add_init(MemoryRegion 
*parent,
                           "acpi-gpe0", GPE_LEN);
     memory_region_add_subregion(parent, GPE_BASE, &s->io_gpe);
 
-    acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent,
-                    s->use_acpi_hotplug_bridge);
+    if (s->use_acpi_hotplug_bridge || s->use_acpi_root_pci_hotplug) {
+        acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent,
+                        s->use_acpi_hotplug_bridge);
+    }
 
     s->cpu_hotplug_legacy = true;
     object_property_add_bool(OBJECT(s), "cpu-hotplug-legacy",
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index e079b686f5..e41bb0992b 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -95,6 +95,7 @@ typedef struct AcpiPmInfo {
     bool s3_disabled;
     bool s4_disabled;
     bool pcihp_bridge_en;
+    bool pcihp_root_en;
     uint8_t s4_val;
     AcpiFadtData fadt;
     uint16_t cpu_hp_io_base;
@@ -245,6 +246,9 @@ static void acpi_get_pm_info(MachineState *machine, 
AcpiPmInfo *pm)
     pm->pcihp_bridge_en =
         object_property_get_bool(obj, "acpi-pci-hotplug-with-bridge-support",
                                  NULL);
+    pm->pcihp_root_en =
+        object_property_get_bool(obj, "acpi-root-pci-hotplug",
+                                 NULL);
 }
 
 static void acpi_get_misc_info(AcpiMiscInfo *info)
@@ -450,10 +454,12 @@ static void build_append_pci_bus_devices(Aml 
*parent_scope, PCIBus *bus,
     }
 
     /* Append PCNT method to notify about events on local and child buses.
-     * Add unconditionally for root since DSDT expects it.
+     * Add this method for root bus only when hotplug is enabled since DSDT
+     * expects it.
      */
-    method = aml_method("PCNT", 0, AML_NOTSERIALIZED);
-
+    if (bsel || pcihp_bridge_en) {
+        method = aml_method("PCNT", 0, AML_NOTSERIALIZED);
+    }
     /* If bus supports hotplug select it and notify about local events */
     if (bsel) {
         uint64_t bsel_val = qnum_get_uint(qobject_to(QNum, bsel));
@@ -479,7 +485,10 @@ static void build_append_pci_bus_devices(Aml 
*parent_scope, PCIBus *bus,
             aml_append(method, aml_name("^S%.02X.PCNT", devfn));
         }
     }
-    aml_append(parent_scope, method);
+
+    if (bsel || pcihp_bridge_en) {
+        aml_append(parent_scope, method);
+    }
     qobject_unref(bsel);
 }
 
@@ -1504,7 +1513,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         build_hpet_aml(dsdt);
         build_piix4_isa_bridge(dsdt);
         build_isa_devices_aml(dsdt);
-        build_piix4_pci_hotplug(dsdt);
+        if (pm->pcihp_bridge_en || pm->pcihp_root_en) {
+            build_piix4_pci_hotplug(dsdt);
+        }
         build_piix4_pci0_int(dsdt);
     } else {
         sb_scope = aml_scope("_SB");
@@ -1546,7 +1557,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
     {
         aml_append(scope, aml_name_decl("_HID", aml_string("ACPI0006")));
 
-        if (misc->is_piix4) {
+        if (misc->is_piix4 && (pm->pcihp_bridge_en || pm->pcihp_root_en)) {
             method = aml_method("_E01", 0, AML_NOTSERIALIZED);
             aml_append(method,
                 aml_acquire(aml_name("\\_SB.PCI0.BLCK"), 0xFFFF));
@@ -1698,7 +1709,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
     crs_range_set_free(&crs_range_set);
 
     /* reserve PCIHP resources */
-    if (pm->pcihp_io_len) {
+    if (pm->pcihp_io_len && (pm->pcihp_bridge_en || pm->pcihp_root_en)) {
         dev = aml_device("PHPR");
         aml_append(dev, aml_name_decl("_HID", aml_string("PNP0A06")));
         aml_append(dev,
-- 
2.17.1