reset: allow registering handlers that aren't called by snapshot loading

Snapshot loading only expects to call deterministic handlers, not
non-deterministic ones. So introduce a way of registering handlers that
won't be called when reseting for snapshots.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Message-id: 20221025004327.568476-2-Jason@zx2c4.com
[PMM: updated json doc comment with Markus' text; fixed
 checkpatch style nit]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/hw/core/reset.c b/hw/core/reset.c
index 36be82c491..d3263b613e 100644
--- a/hw/core/reset.c
+++ b/hw/core/reset.c
@@ -33,6 +33,7 @@ typedef struct QEMUResetEntry {
     QTAILQ_ENTRY(QEMUResetEntry) entry;
     QEMUResetHandler *func;
     void *opaque;
+    bool skip_on_snapshot_load;
 } QEMUResetEntry;
 
 static QTAILQ_HEAD(, QEMUResetEntry) reset_handlers =
@@ -47,6 +48,16 @@ void qemu_register_reset(QEMUResetHandler *func, void *opaque)
     QTAILQ_INSERT_TAIL(&reset_handlers, re, entry);
 }
 
+void qemu_register_reset_nosnapshotload(QEMUResetHandler *func, void *opaque)
+{
+    QEMUResetEntry *re = g_new0(QEMUResetEntry, 1);
+
+    re->func = func;
+    re->opaque = opaque;
+    re->skip_on_snapshot_load = true;
+    QTAILQ_INSERT_TAIL(&reset_handlers, re, entry);
+}
+
 void qemu_unregister_reset(QEMUResetHandler *func, void *opaque)
 {
     QEMUResetEntry *re;
@@ -60,12 +71,16 @@ void qemu_unregister_reset(QEMUResetHandler *func, void *opaque)
     }
 }
 
-void qemu_devices_reset(void)
+void qemu_devices_reset(ShutdownCause reason)
 {
     QEMUResetEntry *re, *nre;
 
     /* reset all devices */
     QTAILQ_FOREACH_SAFE(re, &reset_handlers, entry, nre) {
+        if (reason == SHUTDOWN_CAUSE_SNAPSHOT_LOAD &&
+            re->skip_on_snapshot_load) {
+            continue;
+        }
         re->func(re->opaque);
     }
 }