pc: add SMM property

The property can take values on, off or auto.  The default is "off"
for KVM and pre-2.4 machines, otherwise "auto" (which makes it
available on TCG or on new-enough kernels).

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/i386/pc.c

@@ -1768,6 +1768,48 @@ static void pc_machine_set_vmport(Object *obj, Visitor *v, void *opaque,
     visit_type_OnOffAuto(v, &pcms->vmport, name, errp);
 }
 
+bool pc_machine_is_smm_enabled(PCMachineState *pcms)
+{
+    bool smm_available = false;
+
+    if (pcms->smm == ON_OFF_AUTO_OFF) {
+        return false;
+    }
+
+    if (tcg_enabled() || qtest_enabled()) {
+        smm_available = true;
+    } else if (kvm_enabled()) {
+        smm_available = kvm_has_smm();
+    }
+
+    if (smm_available) {
+        return true;
+    }
+
+    if (pcms->smm == ON_OFF_AUTO_ON) {
+        error_report("System Management Mode not supported by this hypervisor.");
+        exit(1);
+    }
+    return false;
+}
+
+static void pc_machine_get_smm(Object *obj, Visitor *v, void *opaque,
+                              const char *name, Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+    OnOffAuto smm = pcms->smm;
+
+    visit_type_OnOffAuto(v, &smm, name, errp);
+}
+
+static void pc_machine_set_smm(Object *obj, Visitor *v, void *opaque,
+                                  const char *name, Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+
+    visit_type_OnOffAuto(v, &pcms->smm, name, errp);
+}
+
 static bool pc_machine_get_aligned_dimm(Object *obj, Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
@@ -1792,6 +1834,15 @@ static void pc_machine_initfn(Object *obj)
                                     "Maximum ram below the 4G boundary (32bit boundary)",
                                     NULL);
 
+    pcms->smm = ON_OFF_AUTO_AUTO;
+    object_property_add(obj, PC_MACHINE_SMM, "OnOffAuto",
+                        pc_machine_get_smm,
+                        pc_machine_set_smm,
+                        NULL, NULL, NULL);
+    object_property_set_description(obj, PC_MACHINE_SMM,
+                                    "Enable SMM (pc & q35)",
+                                    NULL);
+
     pcms->vmport = ON_OFF_AUTO_AUTO;
     object_property_add(obj, PC_MACHINE_VMPORT, "OnOffAuto",
                         pc_machine_get_vmport,

hw/i386/pc_piix.c

@@ -287,7 +287,8 @@ static void pc_init1(MachineState *machine)
         /* TODO: Populate SPD eeprom data.  */
         smbus = piix4_pm_init(pci_bus, piix3_devfn + 3, 0xb100,
                               gsi[9], smi_irq,
-                              !kvm_enabled(), &piix4_pm);
+                              pc_machine_is_smm_enabled(pc_machine),
+                              &piix4_pm);
         smbus_eeprom_init(smbus, 8, NULL, 0);
 
         object_property_add_link(OBJECT(machine), PC_MACHINE_ACPI_DEVICE_PROP,
@@ -306,7 +307,11 @@ static void pc_init1(MachineState *machine)
 
 static void pc_compat_2_3(MachineState *machine)
 {
+    PCMachineState *pcms = PC_MACHINE(machine);
     savevm_skip_section_footers();
+    if (kvm_enabled()) {
+        pcms->smm = ON_OFF_AUTO_OFF;
+    }
 }
 
 static void pc_compat_2_2(MachineState *machine)

hw/i386/pc_q35.c

@@ -253,7 +253,7 @@ static void pc_q35_init(MachineState *machine)
                          (pc_machine->vmport != ON_OFF_AUTO_ON), 0xff0104);
 
     /* connect pm stuff to lpc */
-    ich9_lpc_pm_init(lpc, !kvm_enabled());
+    ich9_lpc_pm_init(lpc, pc_machine_is_smm_enabled(pc_machine));
 
     /* ahci and SATA device, for q35 1 ahci controller is built-in */
     ahci = pci_create_simple_multifunction(host_bus,
@@ -290,7 +290,11 @@ static void pc_q35_init(MachineState *machine)
 
 static void pc_compat_2_3(MachineState *machine)
 {
+    PCMachineState *pcms = PC_MACHINE(machine);
     savevm_skip_section_footers();
+    if (kvm_enabled()) {
+        pcms->smm = ON_OFF_AUTO_OFF;
+    }
 }
 
 static void pc_compat_2_2(MachineState *machine)

include/hw/i386/pc.h

@@ -37,6 +37,7 @@ struct PCMachineState {
 
     uint64_t max_ram_below_4g;
     OnOffAuto vmport;
+    OnOffAuto smm;
     bool enforce_aligned_dimm;
 };
 
@@ -44,6 +45,7 @@ struct PCMachineState {
 #define PC_MACHINE_MEMHP_REGION_SIZE "hotplug-memory-region-size"
 #define PC_MACHINE_MAX_RAM_BELOW_4G "max-ram-below-4g"
 #define PC_MACHINE_VMPORT           "vmport"
+#define PC_MACHINE_SMM              "smm"
 #define PC_MACHINE_ENFORCE_ALIGNED_DIMM "enforce-aligned-dimm"
 
 /**
@@ -155,6 +157,7 @@ void i8042_setup_a20_line(ISADevice *dev, qemu_irq *a20_out);
 /* pc.c */
 extern int fd_bootchk;
 
+bool pc_machine_is_smm_enabled(PCMachineState *pcms);
 void pc_register_ferr_irq(qemu_irq irq);
 void pc_acpi_smi_interrupt(void *opaque, int irq, int level);
 

target-i386/kvm-stub.c

@@ -18,6 +18,11 @@ bool kvm_allows_irq0_override(void)
 }
 
 #ifndef __OPTIMIZE__
+bool kvm_has_smm(void)
+{
+    return 1;
+}
+
 /* This function is only called inside conditionals which we
  * rely on the compiler to optimize out when CONFIG_KVM is not
  * defined.

target-i386/kvm.c

@@ -86,6 +86,11 @@ static bool has_msr_xss;
 static bool has_msr_architectural_pmu;
 static uint32_t num_architectural_pmu_counters;
 
+bool kvm_has_smm(void)
+{
+    return kvm_check_extension(kvm_state, KVM_CAP_X86_SMM);
+}
+
 bool kvm_allows_irq0_override(void)
 {
     return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing();

target-i386/kvm_i386.h

@@ -14,6 +14,7 @@
 #include "sysemu/kvm.h"
 
 bool kvm_allows_irq0_override(void);
+bool kvm_has_smm(void);
 void kvm_arch_reset_vcpu(X86CPU *cs);
 void kvm_arch_do_init_vcpu(X86CPU *cs);