[PATCH v2 1/7] x86: lpc9: let firmware negotiate 'CPU hotplug with SMI' features

[Igor Mammedov]

It will allow firmware to notify QEMU that firmware requires SMI
being triggered on CPU hot[un]plug, so that it would be able to account
for hotplugged CPU and relocate it to new SMM base and/or safely remove
CPU on unplug.

Using negotiated features, follow up patches will insert SMI upcall
into AML code, to make sure that firmware processes hotplug before
guest OS would attempt to use new CPU.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
---
v2:
  - rebase on top of 5.1 (move compat values to 5.1 machine)
  - make "x-smi-cpu-hotunplug" false by default (Laszlo Ersek 
<lersek@redhat.com>)
---
 include/hw/i386/ich9.h |  2 ++
 include/hw/i386/pc.h   |  3 +++
 hw/i386/pc.c           |  6 +++++-
 hw/i386/pc_piix.c      |  1 +
 hw/i386/pc_q35.c       |  1 +
 hw/isa/lpc_ich9.c      | 13 +++++++++++++
 6 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/include/hw/i386/ich9.h b/include/hw/i386/ich9.h
index a98d10b252..d1bb3f7bf0 100644
--- a/include/hw/i386/ich9.h
+++ b/include/hw/i386/ich9.h
@@ -247,5 +247,7 @@ typedef struct ICH9LPCState {
 
 /* bit positions used in fw_cfg SMI feature negotiation */
 #define ICH9_LPC_SMI_F_BROADCAST_BIT            0
+#define ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT          1
+#define ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT       2
 
 #endif /* HW_ICH9_H */
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 3d7ed3a55e..fe52e165b2 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -193,6 +193,9 @@ void pc_system_firmware_init(PCMachineState *pcms, 
MemoryRegion *rom_memory);
 void pc_madt_cpu_entry(AcpiDeviceIf *adev, int uid,
                        const CPUArchIdList *apic_ids, GArray *entry);
 
+extern GlobalProperty pc_compat_5_1[];
+extern const size_t pc_compat_5_1_len;
+
 extern GlobalProperty pc_compat_5_0[];
 extern const size_t pc_compat_5_0_len;
 
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 47c5ca3e34..99c6bdbab4 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -97,8 +97,12 @@
 #include "fw_cfg.h"
 #include "trace.h"
 
-GlobalProperty pc_compat_5_0[] = {
+GlobalProperty pc_compat_5_1[] = {
+    { "ICH9-LPC", "x-smi-cpu-hotplug", "off" },
 };
+const size_t pc_compat_5_1_len = G_N_ELEMENTS(pc_compat_5_1);
+
+GlobalProperty pc_compat_5_0[] = { };
 const size_t pc_compat_5_0_len = G_N_ELEMENTS(pc_compat_5_0);
 
 GlobalProperty pc_compat_4_2[] = {
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index b789e83f9a..d56f2e1b96 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -433,6 +433,7 @@ static void pc_i440fx_5_1_machine_options(MachineClass *m)
     m->alias = "pc";
     m->is_default = true;
     pcmc->default_cpu_version = 1;
+    compat_props_add(m->compat_props, pc_compat_5_1, pc_compat_5_1_len);
 }
 
 DEFINE_I440FX_MACHINE(v5_1, "pc-i440fx-5.1", NULL,
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index a3e607a544..0ca1146a59 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -359,6 +359,7 @@ static void pc_q35_5_1_machine_options(MachineClass *m)
     pc_q35_machine_options(m);
     m->alias = "q35";
     pcmc->default_cpu_version = 1;
+    compat_props_add(m->compat_props, pc_compat_5_1, pc_compat_5_1_len);
 }
 
 DEFINE_Q35_MACHINE(v5_1, "pc-q35-5.1", NULL,
diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
index cd6e169d47..19f32bed3e 100644
--- a/hw/isa/lpc_ich9.c
+++ b/hw/isa/lpc_ich9.c
@@ -373,6 +373,15 @@ static void smi_features_ok_callback(void *opaque)
         /* guest requests invalid features, leave @features_ok at zero */
         return;
     }
+    if (!(guest_features & BIT_ULL(ICH9_LPC_SMI_F_BROADCAST_BIT)) &&
+        guest_features & (BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT) |
+                          BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT))) {
+        /*
+         * cpu hot-[un]plug with SMI requires SMI broadcast,
+         * leave @features_ok at zero
+         */
+        return;
+    }
 
     /* valid feature subset requested, lock it down, report success */
     lpc->smi_negotiated_features = guest_features;
@@ -747,6 +756,10 @@ static Property ich9_lpc_properties[] = {
     DEFINE_PROP_BOOL("noreboot", ICH9LPCState, pin_strap.spkr_hi, true),
     DEFINE_PROP_BIT64("x-smi-broadcast", ICH9LPCState, smi_host_features,
                       ICH9_LPC_SMI_F_BROADCAST_BIT, true),
+    DEFINE_PROP_BIT64("x-smi-cpu-hotplug", ICH9LPCState, smi_host_features,
+                      ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT, true),
+    DEFINE_PROP_BIT64("x-smi-cpu-hotunplug", ICH9LPCState, smi_host_features,
+                      ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
-- 
2.26.2