[PATCH] q35: flip acpi-pci-hotplug-with-bridge-support default back to off

[Gerd Hoffmann <kraxel@redhat.com>]

Switch qemu 6.2 back to 6.0 behavior (aka native pcie hotplug) because
acpi hotplug for pcie ports caused all kinds of regressions and a fix
for those is not in sight.

Add compat property for 6.1 to keep it enabled there.  Use a separate
compat property list so we can apply it to 6.1 only.

Fixes: https://gitlab.com/qemu-project/qemu/-/issues/641
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2006409
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/acpi/ich9.c   |  2 +-
 hw/i386/pc.c     |  1 -
 hw/i386/pc_q35.c | 14 +++++++++++++-
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
index 1ee2ba2c508c..6e7d4c9eb54a 100644
--- a/hw/acpi/ich9.c
+++ b/hw/acpi/ich9.c
@@ -427,7 +427,7 @@ void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs *pm)
     pm->disable_s3 = 0;
     pm->disable_s4 = 0;
     pm->s4_val = 2;
-    pm->use_acpi_hotplug_bridge = true;
+    pm->use_acpi_hotplug_bridge = false;
 
     object_property_add_uint32_ptr(obj, ACPI_PM_PROP_PM_IO_BASE,
                                    &pm->pm_io_base, OBJ_PROP_FLAG_READ);
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2592a821486f..4fed82dafcf0 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -106,7 +106,6 @@ GlobalProperty pc_compat_6_0[] = {
     { "qemu64" "-" TYPE_X86_CPU, "model", "6" },
     { "qemu64" "-" TYPE_X86_CPU, "stepping", "3" },
     { TYPE_X86_CPU, "x-vendor-cpuid-only", "off" },
-    { "ICH9-LPC", ACPI_PM_PROP_ACPI_PCIHP_BRIDGE, "off" },
 };
 const size_t pc_compat_6_0_len = G_N_ELEMENTS(pc_compat_6_0);
 
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 797e09500b15..735dd3cff4ed 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -375,8 +375,20 @@ static void pc_q35_6_1_machine_options(MachineClass *m)
     m->smp_props.prefer_sockets = true;
 }
 
+/* 6.1 only compat property (not applied to 6.0 + older) */
+static GlobalProperty pc_compat_6_1_only[] = {
+    { "ICH9-LPC", ACPI_PM_PROP_ACPI_PCIHP_BRIDGE, "on" },
+};
+static const size_t pc_compat_6_1_only_len = G_N_ELEMENTS(pc_compat_6_1_only);
+
+static void pc_q35_6_1_only_machine_options(MachineClass *m)
+{
+    pc_q35_6_1_machine_options(m);
+    compat_props_add(m->compat_props, pc_compat_6_1_only, pc_compat_6_1_only_len);
+}
+
 DEFINE_Q35_MACHINE(v6_1, "pc-q35-6.1", NULL,
-                   pc_q35_6_1_machine_options);
+                   pc_q35_6_1_only_machine_options);
 
 static void pc_q35_6_0_machine_options(MachineClass *m)
 {
-- 
2.33.1