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[Xen-devel] [PATCH v5 2/4] 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 a QAPI enum ShutdownCause that describes reasons
that a shutdown can be requested, and changes qemu_system_reset() to
pass the reason through, although for now it is not reported.  The
next patch will actually wire things up to modify events to report
data based on the reason, and to pass the correct enum value in from
various call-sites that can trigger a reset/shutdown.  Since QAPI
generates enums starting at 0, it's easier if we use a different
number as our sentinel that no request has happened yet.  Most of
the changes are in vl.c, but xen was using things externally.

Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>

---
v4: s/ShutdownType/ShutdownCause/, no thanks to mingw header pollution
v3: new patch
---
 qapi-schema.json        | 23 +++++++++++++++++++++++
 include/sysemu/sysemu.h |  2 +-
 vl.c                    | 44 ++++++++++++++++++++++++++++----------------
 hw/i386/xen/xen-hvm.c   |  9 ++++++---
 migration/colo.c        |  2 +-
 migration/savevm.c      |  2 +-
 6 files changed, 60 insertions(+), 22 deletions(-)

diff --git a/qapi-schema.json b/qapi-schema.json
index 01b087f..a4ebdd1 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2304,6 +2304,29 @@
 { 'command': 'system_powerdown' }

 ##
+# @ShutdownCause:
+#
+# Enumeration of various causes for shutdown.
+#
+# @host-qmp: Reaction to a QMP command, such as 'quit'
+# @host-signal: Reaction to a signal, such as SIGINT
+# @host-ui: Reaction to a UI event, such as closing the window
+# @host-replay: The host is replaying an earlier shutdown event
+# @host-error: Qemu encountered an error that prevents further use of the guest
+# @guest-shutdown: The guest requested a shutdown, such as via ACPI or
+#                  other hardware-specific action
+# @guest-reset: The guest requested a reset, and the command line
+#               response to a reset is to instead trigger a shutdown
+# @guest-panic: The guest panicked, and the command line response to
+#               a panic is to trigger a shutdown
+#
+# Since: 2.10
+##
+{ 'enum': 'ShutdownCause',
+  'data': [ 'host-qmp', 'host-signal', 'host-ui', 'host-replay', 'host-error',
+            'guest-shutdown', 'guest-reset', 'guest-panic' ] }
+
+##
 # @cpu:
 #
 # This command is a nop that is only provided for the purposes of 
compatibility.
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 16175f7..00a907f 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -65,7 +65,7 @@ bool qemu_vmstop_requested(RunState *r);
 int qemu_shutdown_requested_get(void);
 int qemu_reset_requested_get(void);
 void qemu_system_killed(int signal, pid_t pid);
-void qemu_system_reset(bool report);
+void qemu_system_reset(bool report, int reason);
 void qemu_system_guest_panicked(GuestPanicInformation *info);
 size_t qemu_target_page_size(void);

diff --git a/vl.c b/vl.c
index 879786a..2b95b7f 100644
--- a/vl.c
+++ b/vl.c
@@ -1597,8 +1597,8 @@ void vm_state_notify(int running, RunState state)
     }
 }

-static int reset_requested;
-static int shutdown_requested, shutdown_signal;
+static int reset_requested = -1;
+static int shutdown_requested = -1, shutdown_signal;
 static pid_t shutdown_pid;
 static int powerdown_requested;
 static int debug_requested;
@@ -1624,7 +1624,7 @@ int qemu_reset_requested_get(void)

 static int qemu_shutdown_requested(void)
 {
-    return atomic_xchg(&shutdown_requested, 0);
+    return atomic_xchg(&shutdown_requested, -1);
 }

 static void qemu_kill_report(void)
@@ -1650,11 +1650,11 @@ static void qemu_kill_report(void)
 static int qemu_reset_requested(void)
 {
     int r = reset_requested;
-    if (r && replay_checkpoint(CHECKPOINT_RESET_REQUESTED)) {
-        reset_requested = 0;
+    if (r >= 0 && replay_checkpoint(CHECKPOINT_RESET_REQUESTED)) {
+        reset_requested = -1;
         return r;
     }
-    return false;
+    return -1;
 }

 static int qemu_suspend_requested(void)
@@ -1686,7 +1686,12 @@ static int qemu_debug_requested(void)
     return r;
 }

-void qemu_system_reset(bool report)
+/*
+ * Reset the VM. If @report is VMRESET_REPORT, issue an event, using
+ * the @reason interpreted as ShutdownType for details.  Otherwise,
+ * @report is VMRESET_SILENT and @reason is ignored.
+ */
+void qemu_system_reset(bool report, int reason)
 {
     MachineClass *mc;

@@ -1700,6 +1705,7 @@ void qemu_system_reset(bool report)
         qemu_devices_reset();
     }
     if (report) {
+        assert(reason >= 0);
         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;
+        /* FIXME - add a parameter to allow callers to specify reason */
+        shutdown_requested = SHUTDOWN_CAUSE_GUEST_RESET;
     } else {
-        reset_requested = 1;
+        reset_requested = SHUTDOWN_CAUSE_GUEST_RESET;
     }
     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;
+    /* FIXME - add a parameter to allow callers to specify reason */
+    shutdown_requested = SHUTDOWN_CAUSE_GUEST_SHUTDOWN;
     qemu_notify_event();
 }

@@ -1846,13 +1854,16 @@ void qemu_system_debug_request(void)
 static bool main_loop_should_exit(void)
 {
     RunState r;
+    int 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 >= 0) {
         qemu_kill_report();
         qapi_event_send_shutdown(&error_abort);
         if (no_shutdown) {
@@ -1861,9 +1872,10 @@ static bool main_loop_should_exit(void)
             return true;
         }
     }
-    if (qemu_reset_requested()) {
+    request = qemu_reset_requested();
+    if (request >= 0) {
         pause_all_vcpus();
-        qemu_system_reset(VMRESET_REPORT);
+        qemu_system_reset(VMRESET_REPORT, request);
         resume_all_vcpus();
         if (!runstate_check(RUN_STATE_RUNNING) &&
                 !runstate_check(RUN_STATE_INMIGRATE)) {
@@ -1872,7 +1884,7 @@ static bool main_loop_should_exit(void)
     }
     if (qemu_wakeup_requested()) {
         pause_all_vcpus();
-        qemu_system_reset(VMRESET_SILENT);
+        qemu_system_reset(VMRESET_SILENT, -1);
         notifier_list_notify(&wakeup_notifiers, &wakeup_reason);
         wakeup_reason = QEMU_WAKEUP_REASON_NONE;
         resume_all_vcpus();
@@ -4684,7 +4696,7 @@ 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(VMRESET_SILENT, -1);
     register_global_state();
     if (replay_mode != REPLAY_MODE_NONE) {
         replay_vmstate_init();
diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
index b1c05ff..3a6484c 100644
--- a/hw/i386/xen/xen-hvm.c
+++ b/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()) {
-            if (qemu_shutdown_requested_get()) {
+            int request;
+
+            if (qemu_shutdown_requested_get() >= 0) {
                 destroy_hvm_domain(false);
             }
-            if (qemu_reset_requested_get()) {
-                qemu_system_reset(VMRESET_REPORT);
+            request = qemu_reset_requested_get();
+            if (request >= 0) {
+                qemu_system_reset(VMRESET_REPORT, request);
                 destroy_hvm_domain(true);
             }
         }
diff --git a/migration/colo.c b/migration/colo.c
index c19eb3f..17a5482 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -611,7 +611,7 @@ void *colo_process_incoming_thread(void *opaque)
         }

         qemu_mutex_lock_iothread();
-        qemu_system_reset(VMRESET_SILENT);
+        qemu_system_reset(VMRESET_SILENT, -1);
         vmstate_loading = true;
         if (qemu_loadvm_state(fb) < 0) {
             error_report("COLO: loadvm failed");
diff --git a/migration/savevm.c b/migration/savevm.c
index 03ae1bd..dcbaf00 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2292,7 +2292,7 @@ int load_vmstate(const char *name)
         return -EINVAL;
     }

-    qemu_system_reset(VMRESET_SILENT);
+    qemu_system_reset(VMRESET_SILENT, -1);
     mis->from_src_file = f;

     aio_context_acquire(aio_context);
-- 
2.9.3


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