i386/cpu: add crash-information QOM property

Windows reports BSOD parameters through Hyper-V crash MSRs. This
information is very useful for initial crash analysis and thus
it would be nice to have a way to fetch it.

Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Message-Id: <1487053524-18674-2-git-send-email-den@openvz.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

kvm-all.c

@@ -2000,6 +2000,7 @@ int kvm_cpu_exec(CPUState *cpu)
                 ret = EXCP_INTERRUPT;
                 break;
             case KVM_SYSTEM_EVENT_CRASH:
+                kvm_cpu_synchronize_state(cpu);
                 qemu_mutex_lock_iothread();
                 qemu_system_guest_panicked();
                 qemu_mutex_unlock_iothread();

qapi-schema.json

@@ -5870,6 +5870,30 @@
 { 'enum': 'GuestPanicAction',
   'data': [ 'pause', 'poweroff' ] }
 
+##
+# @GuestPanicInformation:
+#
+# Information about a guest panic
+#
+# Since: 2.9
+##
+{'union': 'GuestPanicInformation',
+ 'data': { 'hyper-v': 'GuestPanicInformationHyperV' } }
+
+##
+# @GuestPanicInformationHyperV:
+#
+# Hyper-V specific guest panic information (HV crash MSRs)
+#
+# Since: 2.9
+##
+{'struct': 'GuestPanicInformationHyperV',
+ 'data': { 'arg1': 'uint64',
+           'arg2': 'uint64',
+           'arg3': 'uint64',
+           'arg4': 'uint64',
+           'arg5': 'uint64' } }
+
 ##
 # @rtc-reset-reinjection:
 #

target/i386/cpu.c

@@ -3495,6 +3495,53 @@ static void x86_cpu_register_feature_bit_props(X86CPU *cpu,
     x86_cpu_register_bit_prop(cpu, name, &cpu->env.features[w], bitnr);
 }
 
+static GuestPanicInformation *x86_cpu_get_crash_info(CPUState *cs)
+{
+    X86CPU *cpu = X86_CPU(cs);
+    CPUX86State *env = &cpu->env;
+    GuestPanicInformation *panic_info = NULL;
+
+    if (env->features[FEAT_HYPERV_EDX] & HV_X64_GUEST_CRASH_MSR_AVAILABLE) {
+        GuestPanicInformationHyperV *panic_info_hv =
+            g_malloc0(sizeof(GuestPanicInformationHyperV));
+        panic_info = g_malloc0(sizeof(GuestPanicInformation));
+
+        panic_info->type = GUEST_PANIC_INFORMATION_KIND_HYPER_V;
+        panic_info->u.hyper_v.data = panic_info_hv;
+
+        assert(HV_X64_MSR_CRASH_PARAMS >= 5);
+        panic_info_hv->arg1 = env->msr_hv_crash_params[0];
+        panic_info_hv->arg2 = env->msr_hv_crash_params[1];
+        panic_info_hv->arg3 = env->msr_hv_crash_params[2];
+        panic_info_hv->arg4 = env->msr_hv_crash_params[3];
+        panic_info_hv->arg5 = env->msr_hv_crash_params[4];
+    }
+
+    return panic_info;
+}
+static void x86_cpu_get_crash_info_qom(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    CPUState *cs = CPU(obj);
+    GuestPanicInformation *panic_info;
+
+    if (!cs->crash_occurred) {
+        error_setg(errp, "No crash occured");
+        return;
+    }
+
+    panic_info = x86_cpu_get_crash_info(cs);
+    if (panic_info == NULL) {
+        error_setg(errp, "No crash information");
+        return;
+    }
+
+    visit_type_GuestPanicInformation(v, "crash-information", &panic_info,
+                                     errp);
+    qapi_free_GuestPanicInformation(panic_info);
+}
+
 static void x86_cpu_initfn(Object *obj)
 {
     CPUState *cs = CPU(obj);
@@ -3530,6 +3577,9 @@ static void x86_cpu_initfn(Object *obj)
                         x86_cpu_get_feature_words,
                         NULL, NULL, (void *)cpu->filtered_features, NULL);
 
+    object_property_add(obj, "crash-information", "GuestPanicInformation",
+                        x86_cpu_get_crash_info_qom, NULL, NULL, NULL, NULL);
+
     cpu->hyperv_spinlock_attempts = HYPERV_SPINLOCK_NEVER_RETRY;
 
     for (w = 0; w < FEATURE_WORDS; w++) {