[PATCH] Introduce global piix flag to disable PCI hotplug

[Ani Sinha <ani@anisinha.ca>]

We introduce a new global flag for PIIX with which we can
turn on or off PCI device hotplug. This flag can be used
to prevent all PCI devices from getting hotplugged/unplugged
on the PCI bus. The new options disables all hotpluh HW
initialization code as well as the ACPI AMLs.

Signed-off-by: Ani Sinha <ani@anisinha.ca>
---
 hw/acpi/piix4.c      |  8 ++++++--
 hw/i386/acpi-build.c | 20 ++++++++++++++------
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index 26bac4f..8b13e86 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -78,6 +78,7 @@ typedef struct PIIX4PMState {
 
     AcpiPciHpState acpi_pci_hotplug;
     bool use_acpi_hotplug_bridge;
+    bool use_acpi_pci_hotplug;
 
     uint8_t disable_s3;
     uint8_t disable_s4;
@@ -595,8 +596,9 @@ 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_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",
@@ -635,6 +637,8 @@ static Property piix4_pm_properties[] = {
     DEFINE_PROP_UINT8(ACPI_PM_PROP_S4_VAL, PIIX4PMState, s4_val, 2),
     DEFINE_PROP_BOOL("acpi-pci-hotplug-with-bridge-support", PIIX4PMState,
                      use_acpi_hotplug_bridge, true),
+    DEFINE_PROP_BOOL("acpi-pci-hotplug", PIIX4PMState,
+                     use_acpi_pci_hotplug, true),
     DEFINE_PROP_BOOL("memory-hotplug-support", PIIX4PMState,
                      acpi_memory_hotplug.is_enabled, true),
     DEFINE_PROP_END_OF_LIST(),
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index b7bcbbb..343b9b6 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_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_en =
+        object_property_get_bool(obj, "acpi-pci-hotplug", NULL);
+
 }
 
 static void acpi_get_misc_info(AcpiMiscInfo *info)
@@ -337,14 +341,16 @@ static void build_append_pcihp_notify_entry(Aml *method, int slot)
 }
 
 static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
-                                         bool pcihp_bridge_en)
+                                         bool pcihp_bridge_en, bool pcihp_en)
 {
     Aml *dev, *notify_method = NULL, *method;
-    QObject *bsel;
+    QObject *bsel = NULL;
     PCIBus *sec;
     int i;
 
-    bsel = object_property_get_qobject(OBJECT(bus), ACPI_PCIHP_PROP_BSEL, NULL);
+    if (pcihp_en)
+        bsel = object_property_get_qobject(OBJECT(bus),
+                                           ACPI_PCIHP_PROP_BSEL, NULL);
     if (bsel) {
         uint64_t bsel_val = qnum_get_uint(qobject_to(QNum, bsel));
 
@@ -439,7 +445,8 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
              */
             PCIBus *sec_bus = pci_bridge_get_sec_bus(PCI_BRIDGE(pdev));
 
-            build_append_pci_bus_devices(dev, sec_bus, pcihp_bridge_en);
+            build_append_pci_bus_devices(dev, sec_bus, pcihp_bridge_en,
+                                         pcihp_en);
         }
         /* slot descriptor has been composed, add it into parent context */
         aml_append(parent_scope, dev);
@@ -468,7 +475,7 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
     }
 
     /* Notify about child bus events in any case */
-    if (pcihp_bridge_en) {
+    if (pcihp_bridge_en && pcihp_en) {
         QLIST_FOREACH(sec, &bus->child, sibling) {
             int32_t devfn = sec->parent_dev->devfn;
 
@@ -1818,7 +1825,8 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         if (bus) {
             Aml *scope = aml_scope("PCI0");
             /* Scan all PCI buses. Generate tables to support hotplug. */
-            build_append_pci_bus_devices(scope, bus, pm->pcihp_bridge_en);
+            build_append_pci_bus_devices(scope, bus, pm->pcihp_bridge_en,
+                                         pm->pcihp_en);
 
             if (TPM_IS_TIS_ISA(tpm)) {
                 if (misc->tpm_version == TPM_VERSION_2_0) {
-- 
2.7.4