shutdown: Prepare for use of an enum in reset/shutdown_request

We want to track why a guest was shutdown; in particular, being able
to tell the difference between a guest request (such as ACPI request)
and host request (such as SIGINT) will prove useful to libvirt.
Since all requests eventually end up changing shutdown_requested in
vl.c, the logical change is to make that value track the reason,
rather than its current 0/1 contents.

Since command-line options control whether a reset request is turned
into a shutdown request instead, the same treatment is given to
reset_requested.

This patch adds an internal enum ShutdownCause that describes reasons
that a shutdown can be requested, and changes qemu_system_reset() to
pass the reason through, although for now nothing is actually changed
with regards to what gets reported.  The enum could be exported via
QAPI at a later date, if deemed necessary, but for now, there has not
been a request to expose that much detail to end clients.

For the most part, we turn 0 into SHUTDOWN_CAUSE_NONE, and 1 into
SHUTDOWN_CAUSE_HOST_ERROR; the only specific case where we have enough
information right now to use a different value is when we are reacting
to a host signal.  It will take a further patch to edit all call-sites
that can trigger a reset or shutdown request to properly pass in any
other reasons; this patch includes TODOs to point such places out.

qemu_system_reset() trades its 'bool report' parameter for a
'ShutdownCause reason', with all non-zero values having the same
effect; this lets us get rid of the weird #defines for VMRESET_*
as synonyms for bools.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170515214114.15442-3-eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

hw/i386/xen/xen-hvm.c

@@ -1089,11 +1089,14 @@ static void cpu_handle_ioreq(void *opaque)
          * causes Xen to powerdown the domain.
          */
         if (runstate_is_running()) {
+            ShutdownCause request;
+
             if (qemu_shutdown_requested_get()) {
                 destroy_hvm_domain(false);
             }
-            if (qemu_reset_requested_get()) {
+            request = qemu_reset_requested_get();
-                qemu_system_reset(VMRESET_REPORT);
+            if (request) {
+                qemu_system_reset(request);
                 destroy_hvm_domain(true);
             }
         }

include/sysemu/sysemu.h

@@ -33,8 +33,21 @@ VMChangeStateEntry *qemu_add_vm_change_state_handler(VMChangeStateHandler *cb,
 void qemu_del_vm_change_state_handler(VMChangeStateEntry *e);
 void vm_state_notify(int running, RunState state);
 
-#define VMRESET_SILENT   false
+/* Enumeration of various causes for shutdown. */
-#define VMRESET_REPORT   true
+typedef enum ShutdownCause {
+    SHUTDOWN_CAUSE_NONE,          /* No shutdown request pending */
+    SHUTDOWN_CAUSE_HOST_ERROR,    /* An error prevents further use of guest */
+    SHUTDOWN_CAUSE_HOST_QMP,      /* Reaction to a QMP command, like 'quit' */
+    SHUTDOWN_CAUSE_HOST_SIGNAL,   /* Reaction to a signal, such as SIGINT */
+    SHUTDOWN_CAUSE_HOST_UI,       /* Reaction to UI event, like window close */
+    SHUTDOWN_CAUSE_GUEST_SHUTDOWN,/* Guest shutdown/suspend request, via
+                                     ACPI or other hardware-specific means */
+    SHUTDOWN_CAUSE_GUEST_RESET,   /* Guest reset request, and command line
+                                     turns that into a shutdown */
+    SHUTDOWN_CAUSE_GUEST_PANIC,   /* Guest panicked, and command line turns
+                                     that into a shutdown */
+    SHUTDOWN_CAUSE__MAX,
+} ShutdownCause;
 
 void vm_start(void);
 int vm_prepare_start(void);
@@ -62,10 +75,10 @@ void qemu_system_debug_request(void);
 void qemu_system_vmstop_request(RunState reason);
 void qemu_system_vmstop_request_prepare(void);
 bool qemu_vmstop_requested(RunState *r);
-int qemu_shutdown_requested_get(void);
+ShutdownCause qemu_shutdown_requested_get(void);
-int qemu_reset_requested_get(void);
+ShutdownCause qemu_reset_requested_get(void);
 void qemu_system_killed(int signal, pid_t pid);
-void qemu_system_reset(bool report);
+void qemu_system_reset(ShutdownCause reason);
 void qemu_system_guest_panicked(GuestPanicInformation *info);
 size_t qemu_target_page_size(void);
 

migration/colo.c

@@ -623,7 +623,7 @@ void *colo_process_incoming_thread(void *opaque)
         }
 
         qemu_mutex_lock_iothread();
-        qemu_system_reset(VMRESET_SILENT);
+        qemu_system_reset(SHUTDOWN_CAUSE_NONE);
         vmstate_loading = true;
         if (qemu_loadvm_state(fb) < 0) {
             error_report("COLO: loadvm failed");

migration/savevm.c

@@ -2285,7 +2285,7 @@ int load_vmstate(const char *name, Error **errp)
         return -EINVAL;
     }
 
-    qemu_system_reset(VMRESET_SILENT);
+    qemu_system_reset(SHUTDOWN_CAUSE_NONE);
     mis->from_src_file = f;
 
     aio_context_acquire(aio_context);

vl.c

@@ -1597,8 +1597,9 @@ void vm_state_notify(int running, RunState state)
     }
 }
 
-static int reset_requested;
+static ShutdownCause reset_requested;
-static int shutdown_requested, shutdown_signal;
+static ShutdownCause shutdown_requested;
+static int shutdown_signal;
 static pid_t shutdown_pid;
 static int powerdown_requested;
 static int debug_requested;
@@ -1612,19 +1613,19 @@ static NotifierList wakeup_notifiers =
     NOTIFIER_LIST_INITIALIZER(wakeup_notifiers);
 static uint32_t wakeup_reason_mask = ~(1 << QEMU_WAKEUP_REASON_NONE);
 
-int qemu_shutdown_requested_get(void)
+ShutdownCause qemu_shutdown_requested_get(void)
 {
     return shutdown_requested;
 }
 
-int qemu_reset_requested_get(void)
+ShutdownCause qemu_reset_requested_get(void)
 {
     return reset_requested;
 }
 
 static int qemu_shutdown_requested(void)
 {
-    return atomic_xchg(&shutdown_requested, 0);
+    return atomic_xchg(&shutdown_requested, SHUTDOWN_CAUSE_NONE);
 }
 
 static void qemu_kill_report(void)
@@ -1647,14 +1648,15 @@ static void qemu_kill_report(void)
     }
 }
 
-static int qemu_reset_requested(void)
+static ShutdownCause qemu_reset_requested(void)
 {
-    int r = reset_requested;
+    ShutdownCause r = reset_requested;
+
     if (r && replay_checkpoint(CHECKPOINT_RESET_REQUESTED)) {
-        reset_requested = 0;
+        reset_requested = SHUTDOWN_CAUSE_NONE;
         return r;
     }
-    return false;
+    return SHUTDOWN_CAUSE_NONE;
 }
 
 static int qemu_suspend_requested(void)
@@ -1686,7 +1688,10 @@ static int qemu_debug_requested(void)
     return r;
 }
 
-void qemu_system_reset(bool report)
+/*
+ * Reset the VM. Issue an event unless @reason is SHUTDOWN_CAUSE_NONE.
+ */
+void qemu_system_reset(ShutdownCause reason)
 {
     MachineClass *mc;
 
@@ -1699,7 +1704,8 @@ void qemu_system_reset(bool report)
     } else {
         qemu_devices_reset();
     }
-    if (report) {
+    if (reason) {
+        /* TODO update event based on reason */
         qapi_event_send_reset(&error_abort);
     }
     cpu_synchronize_all_post_reset();
@@ -1738,9 +1744,10 @@ void qemu_system_guest_panicked(GuestPanicInformation *info)
 void qemu_system_reset_request(void)
 {
     if (no_reboot) {
-        shutdown_requested = 1;
+        /* TODO - add a parameter to allow callers to specify reason */
+        shutdown_requested = SHUTDOWN_CAUSE_HOST_ERROR;
     } else {
-        reset_requested = 1;
+        reset_requested = SHUTDOWN_CAUSE_HOST_ERROR;
     }
     cpu_stop_current();
     qemu_notify_event();
@@ -1807,7 +1814,7 @@ void qemu_system_killed(int signal, pid_t pid)
     /* Cannot call qemu_system_shutdown_request directly because
      * we are in a signal handler.
      */
-    shutdown_requested = 1;
+    shutdown_requested = SHUTDOWN_CAUSE_HOST_SIGNAL;
     qemu_notify_event();
 }
 
@@ -1815,7 +1822,8 @@ void qemu_system_shutdown_request(void)
 {
     trace_qemu_system_shutdown_request();
     replay_shutdown_request();
-    shutdown_requested = 1;
+    /* TODO - add a parameter to allow callers to specify reason */
+    shutdown_requested = SHUTDOWN_CAUSE_HOST_ERROR;
     qemu_notify_event();
 }
 
@@ -1846,14 +1854,18 @@ void qemu_system_debug_request(void)
 static bool main_loop_should_exit(void)
 {
     RunState r;
+    ShutdownCause request;
+
     if (qemu_debug_requested()) {
         vm_stop(RUN_STATE_DEBUG);
     }
     if (qemu_suspend_requested()) {
         qemu_system_suspend();
     }
-    if (qemu_shutdown_requested()) {
+    request = qemu_shutdown_requested();
+    if (request) {
         qemu_kill_report();
+        /* TODO update event based on request */
         qapi_event_send_shutdown(&error_abort);
         if (no_shutdown) {
             vm_stop(RUN_STATE_SHUTDOWN);
@@ -1861,9 +1873,10 @@ static bool main_loop_should_exit(void)
             return true;
         }
     }
-    if (qemu_reset_requested()) {
+    request = qemu_reset_requested();
+    if (request) {
         pause_all_vcpus();
-        qemu_system_reset(VMRESET_REPORT);
+        qemu_system_reset(request);
         resume_all_vcpus();
         if (!runstate_check(RUN_STATE_RUNNING) &&
                 !runstate_check(RUN_STATE_INMIGRATE)) {
@@ -1872,7 +1885,7 @@ static bool main_loop_should_exit(void)
     }
     if (qemu_wakeup_requested()) {
         pause_all_vcpus();
-        qemu_system_reset(VMRESET_SILENT);
+        qemu_system_reset(SHUTDOWN_CAUSE_NONE);
         notifier_list_notify(&wakeup_notifiers, &wakeup_reason);
         wakeup_reason = QEMU_WAKEUP_REASON_NONE;
         resume_all_vcpus();
@@ -4696,7 +4709,7 @@ int main(int argc, char **argv, char **envp)
        reading from the other reads, because timer polling functions query
        clock values from the log. */
     replay_checkpoint(CHECKPOINT_RESET);
-    qemu_system_reset(VMRESET_SILENT);
+    qemu_system_reset(SHUTDOWN_CAUSE_NONE);
     register_global_state();
     if (replay_mode != REPLAY_MODE_NONE) {
         replay_vmstate_init();