[PULL v4 21/48] x86: lpc9: let firmware negotiate 'CPU hotplug with SMI' features

[Michael S. Tsirkin]

From: Igor Mammedov <imammedo@redhat.com>

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>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200923094650.1301166-2-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/hw/i386/ich9.h |  2 ++
 hw/i386/pc.c           |  4 +++-
 hw/isa/lpc_ich9.c      | 13 +++++++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/hw/i386/ich9.h b/include/hw/i386/ich9.h
index 48b442bc0b..703d56036a 100644
--- a/include/hw/i386/ich9.h
+++ b/include/hw/i386/ich9.h
@@ -247,5 +247,7 @@ 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/hw/i386/pc.c b/hw/i386/pc.c
index 50e8317342..2c6194e57f 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -97,7 +97,9 @@
 #include "trace.h"
 #include CONFIG_DEVICES
 
-GlobalProperty pc_compat_5_1[] = {};
+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[] = {
diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
index 3303d2eab6..a54b3ec8bd 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(),
 };
 
-- 
MST