spapr: Add support for new NMI interface

This implements an NMI interface POWERPC SPAPR machine.
This enables an "nmi" HMP/QMP command supported on SPAPR.

This calls POWERPC_EXCP_RESET (vector 0x100) in the guest to deliver NMI
to every CPU. The expected result is XMON (in-kernel debugger) invocation.
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/ppc/spapr.c

@@ -55,6 +55,7 @@
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
 #include "trace.h"
+#include "hw/nmi.h"
 
 #include <libfdt.h>
 
@@ -1576,10 +1577,28 @@ static void spapr_machine_initfn(Object *obj)
                             spapr_get_kvm_type, spapr_set_kvm_type, NULL);
 }
 
+static void ppc_cpu_do_nmi_on_cpu(void *arg)
+{
+    CPUState *cs = arg;
+
+    cpu_synchronize_state(cs);
+    ppc_cpu_do_system_reset(cs);
+}
+
+static void spapr_nmi(NMIState *n, int cpu_index, Error **errp)
+{
+    CPUState *cs;
+
+    CPU_FOREACH(cs) {
+        async_run_on_cpu(cs, ppc_cpu_do_nmi_on_cpu, cs);
+    }
+}
+
 static void spapr_machine_class_init(ObjectClass *oc, void *data)
 {
     MachineClass *mc = MACHINE_CLASS(oc);
     FWPathProviderClass *fwc = FW_PATH_PROVIDER_CLASS(oc);
+    NMIClass *nc = NMI_CLASS(oc);
 
     mc->name = "pseries";
     mc->desc = "pSeries Logical Partition (PAPR compliant)";
@@ -1593,6 +1612,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     mc->kvm_type = spapr_kvm_type;
 
     fwc->get_dev_path = spapr_get_fw_dev_path;
+    nc->nmi_monitor_handler = spapr_nmi;
 }
 
 static const TypeInfo spapr_machine_info = {
@@ -1603,6 +1623,7 @@ static const TypeInfo spapr_machine_info = {
     .class_init    = spapr_machine_class_init,
     .interfaces = (InterfaceInfo[]) {
         { TYPE_FW_PATH_PROVIDER },
+        { TYPE_NMI },
         { }
     },
 };

target-ppc/cpu-qom.h

@@ -127,6 +127,7 @@ int ppc64_cpu_write_elf64_qemunote(WriteCoreDumpFunction f,
 int ppc64_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
                                int cpuid, void *opaque);
 #ifndef CONFIG_USER_ONLY
+void ppc_cpu_do_system_reset(CPUState *cs);
 extern const struct VMStateDescription vmstate_ppc_cpu;
 
 typedef struct PPCTimebase {

target-ppc/excp_helper.c

@@ -810,6 +810,14 @@ void ppc_hw_interrupt(CPUPPCState *env)
         }
     }
 }
+
+void ppc_cpu_do_system_reset(CPUState *cs)
+{
+    PowerPCCPU *cpu = POWERPC_CPU(cs);
+    CPUPPCState *env = &cpu->env;
+
+    powerpc_excp(cpu, env->excp_model, POWERPC_EXCP_RESET);
+}
 #endif /* !CONFIG_USER_ONLY */
 
 #if defined(DEBUG_OP)