On 9/9/2025 11:51 AM, Peter Xu wrote:
On Thu, Aug 14, 2025 at 10:17:18AM -0700, Steve Sistare wrote:
Add a qemu_system_exec_request() hook that causes the main loop to exit and
exec a command using the specified arguments. This will be used during CPR
to exec a new version of QEMU.
Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
---
include/system/runstate.h | 3 +++
system/runstate.c | 29 +++++++++++++++++++++++++++++
2 files changed, 32 insertions(+)
diff --git a/include/system/runstate.h b/include/system/runstate.h
index 929379a..c005f49 100644
--- a/include/system/runstate.h
+++ b/include/system/runstate.h
@@ -128,6 +128,8 @@ typedef enum WakeupReason {
QEMU_WAKEUP_REASON_OTHER,
} WakeupReason;
+typedef void (*qemu_exec_func)(char **exec_argv);
+
void qemu_system_reset_request(ShutdownCause reason);
void qemu_system_suspend_request(void);
void qemu_register_suspend_notifier(Notifier *notifier);
@@ -139,6 +141,7 @@ void qemu_register_wakeup_support(void);
void qemu_system_shutdown_request_with_code(ShutdownCause reason,
int exit_code);
void qemu_system_shutdown_request(ShutdownCause reason);
+void qemu_system_exec_request(qemu_exec_func func, const strList *args);
void qemu_system_powerdown_request(void);
void qemu_register_powerdown_notifier(Notifier *notifier);
void qemu_register_shutdown_notifier(Notifier *notifier);
diff --git a/system/runstate.c b/system/runstate.c
index 6178b00..b4980ff 100644
--- a/system/runstate.c
+++ b/system/runstate.c
@@ -41,6 +41,7 @@
#include "qapi/error.h"
#include "qapi/qapi-commands-run-state.h"
#include "qapi/qapi-events-run-state.h"
+#include "qapi/type-helpers.h"
#include "qemu/accel.h"
#include "qemu/error-report.h"
#include "qemu/job.h"
@@ -422,6 +423,8 @@ static NotifierList wakeup_notifiers =
static NotifierList shutdown_notifiers =
NOTIFIER_LIST_INITIALIZER(shutdown_notifiers);
static uint32_t wakeup_reason_mask = ~(1 << QEMU_WAKEUP_REASON_NONE);
+qemu_exec_func exec_func;
+static char **exec_argv;
ShutdownCause qemu_shutdown_requested_get(void)
{
@@ -443,6 +446,11 @@ static int qemu_shutdown_requested(void)
return qatomic_xchg(&shutdown_requested, SHUTDOWN_CAUSE_NONE);
}
+static int qemu_exec_requested(void)
+{
+ return exec_argv != NULL;
+}
+
static void qemu_kill_report(void)
{
if (!qtest_driver() && shutdown_signal) {
@@ -803,6 +811,23 @@ void qemu_system_shutdown_request(ShutdownCause reason)
qemu_notify_event();
}
+static void qemu_system_exec(void)
+{
+ exec_func(exec_argv);
+
+ /* exec failed */
+ g_strfreev(exec_argv);
+ exec_argv = NULL;
+ exec_func = NULL;
Would this really happen?
If so, do we at least want to dump something?
+}
+
+void qemu_system_exec_request(qemu_exec_func func, const strList *args)
+{
+ exec_func = func;
+ exec_argv = strv_from_str_list(args);
+ qemu_notify_event();
+}
+
static void qemu_system_powerdown(void)
{
qapi_event_send_powerdown();
@@ -849,6 +874,10 @@ static bool main_loop_should_exit(int *status)
if (qemu_suspend_requested()) {
qemu_system_suspend();
}
+ if (qemu_exec_requested()) {
+ qemu_system_exec();
+ return false;
+ }
Some explanation of why it needs to be done explicitly here would be
helpful. E.g., can we do exec inside a BH scheduled for the main thread?
What if we exec() directly in another thread (rather than the main loop
thread)?
A BH is a good idea, thanks.
It only requires a few lines of code, and no globals.
I will drop this patch and add a BH to patch "migration: cpr-exec mode".
- Steve
