reset: Add RESET_TYPE_SNAPSHOT_LOAD

Some devices and machines need to handle the reset before a vmsave
snapshot is loaded differently -- the main user is the handling of
RNG seed information, which does not want to put a new RNG seed into
a ROM blob when we are doing a snapshot load.

Currently this kind of reset handling is supported only for:
 * TYPE_MACHINE reset methods, which take a ShutdownCause argument
 * reset functions registered with qemu_register_reset_nosnapshotload

To allow a three-phase-reset device to also distinguish "snapshot
load" reset from the normal kind, add a new ResetType
RESET_TYPE_SNAPSHOT_LOAD. All our existing reset methods ignore
the reset type, so we don't need to update any device code.

Add the enum type, and make qemu_devices_reset() use the
right reset type for the ShutdownCause it is passed. This
allows us to get rid of the device_reset_reason global we
were using to implement qemu_register_reset_nosnapshotload().

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Luc Michel <luc.michel@amd.com>
Message-id: 20240412160809.1260625-7-peter.maydell@linaro.org

2 files changed, 4 insertions, 15 deletions

diff --git a/hw/core/reset.c b/hw/core/reset.c
index f9fef45e05..58dfc8db3d 100644
--- a/hw/core/reset.c
+++ b/hw/core/reset.c
@@ -44,13 +44,6 @@ static ResettableContainer *get_root_reset_container(void)
 }
 
 /*
- * Reason why the currently in-progress qemu_devices_reset() was called.
- * If we made at least SHUTDOWN_CAUSE_SNAPSHOT_LOAD have a corresponding
- * ResetType we could perhaps avoid the need for this global.
- */
-static ShutdownCause device_reset_reason;
-
-/*
  * This is an Object which implements Resettable simply to call the
  * callback function in the hold phase.
  */
@@ -77,8 +70,7 @@ static void legacy_reset_hold(Object *obj, ResetType type)
 {
     LegacyReset *lr = LEGACY_RESET(obj);
 
-    if (device_reset_reason == SHUTDOWN_CAUSE_SNAPSHOT_LOAD &&
-        lr->skip_on_snapshot_load) {
+    if (type == RESET_TYPE_SNAPSHOT_LOAD && lr->skip_on_snapshot_load) {
         return;
     }
     lr->func(lr->opaque);
@@ -180,8 +172,9 @@ void qemu_unregister_resettable(Object *obj)
 
 void qemu_devices_reset(ShutdownCause reason)
 {
-    device_reset_reason = reason;
+    ResetType type = (reason == SHUTDOWN_CAUSE_SNAPSHOT_LOAD) ?
+        RESET_TYPE_SNAPSHOT_LOAD : RESET_TYPE_COLD;
 
     /* Reset the simulation */
-    resettable_reset(OBJECT(get_root_reset_container()), RESET_TYPE_COLD);
+    resettable_reset(OBJECT(get_root_reset_container()), type);
 }
diff --git a/hw/core/resettable.c b/hw/core/resettable.c
index bebf7f10b2..6dd3e3dc48 100644
--- a/hw/core/resettable.c
+++ b/hw/core/resettable.c
@@ -48,8 +48,6 @@ void resettable_reset(Object *obj, ResetType type)
 
 void resettable_assert_reset(Object *obj, ResetType type)
 {
-    /* TODO: change this assert when adding support for other reset types */
-    assert(type == RESET_TYPE_COLD);
     trace_resettable_reset_assert_begin(obj, type);
     assert(!enter_phase_in_progress);
 
@@ -64,8 +62,6 @@ void resettable_assert_reset(Object *obj, ResetType type)
 
 void resettable_release_reset(Object *obj, ResetType type)
 {
-    /* TODO: change this assert when adding support for other reset types */
-    assert(type == RESET_TYPE_COLD);
     trace_resettable_reset_release_begin(obj, type);
     assert(!enter_phase_in_progress);