[Xen-devel] [PATCH v2 1/6] suspend: add infrastructure

[Gerd Hoffmann <kraxel@xxxxxxxxxx>]

This patch adds some infrastructure to handle suspend and resume to
qemu.  First there are two functions to switch state and second there
is a suspend notifier:

 * qemu_system_suspend_request() is supposed to be called when the
   guest asks for being be suspended, for example via ACPI.

 * qemu_system_wakeup_request is supposed to be called on events which
   should wake up the guest.

 * qemu_register_suspend_notifier can be used to register a notifier
   which will be called when the guest is suspended.  Machine types
   and device models can hook in there to modify state if needed.

Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
 sysemu.h |    3 +++
 vl.c     |   28 ++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/sysemu.h b/sysemu.h
index ddef2bb..22470a3 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -39,6 +39,9 @@ void vm_stop(RunState state);
 void vm_stop_force_state(RunState state);
 
 void qemu_system_reset_request(void);
+void qemu_system_suspend_request(void);
+void qemu_register_suspend_notifier(Notifier *notifier);
+void qemu_system_wakeup_request(void);
 void qemu_system_shutdown_request(void);
 void qemu_system_powerdown_request(void);
 void qemu_system_debug_request(void);
diff --git a/vl.c b/vl.c
index ba55b35..755cd67 100644
--- a/vl.c
+++ b/vl.c
@@ -1282,6 +1282,9 @@ static int shutdown_requested, shutdown_signal = -1;
 static pid_t shutdown_pid;
 static int powerdown_requested;
 static int debug_requested;
+static bool is_suspended;
+static NotifierList suspend_notifiers =
+    NOTIFIER_LIST_INITIALIZER(suspend_notifiers);
 static RunState vmstop_requested = RUN_STATE_MAX;
 
 int qemu_shutdown_requested_get(void)
@@ -1397,6 +1400,31 @@ void qemu_system_reset_request(void)
     qemu_notify_event();
 }
 
+void qemu_system_suspend_request(void)
+{
+    if (is_suspended) {
+        return;
+    }
+    cpu_stop_current();
+    notifier_list_notify(&suspend_notifiers, NULL);
+    is_suspended = true;
+}
+
+void qemu_register_suspend_notifier(Notifier *notifier)
+{
+    notifier_list_add(&suspend_notifiers, notifier);
+}
+
+void qemu_system_wakeup_request(void)
+{
+    if (!is_suspended) {
+        return;
+    }
+    reset_requested = 1;
+    qemu_notify_event();
+    is_suspended = false;
+}
+
 void qemu_system_killed(int signal, pid_t pid)
 {
     shutdown_signal = signal;
-- 
1.7.1


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