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[PATCH v3 2/4] vl: Add option to avoid stopping VM upon guest panic
From: |
Alejandro Jimenez |
Subject: |
[PATCH v3 2/4] vl: Add option to avoid stopping VM upon guest panic |
Date: |
Fri, 11 Dec 2020 11:52:42 -0500 |
The current default action of pausing a guest after a panic event
is received leaves the responsibility to resume guest execution to the
management layer. The reasons for this behavior are discussed here:
https://lore.kernel.org/qemu-devel/52148F88.5000509@redhat.com/
However, in instances like the case of older guests (Linux and
Windows) using a pvpanic device but missing support for the
PVPANIC_CRASHLOADED event, and Windows guests using the hv-crash
enlightenment, it is desirable to allow the guests to continue
running after sending a PVPANIC_PANICKED event. This allows such
guests to proceed to capture a crash dump and automatically reboot
without intervention of a management layer.
Add an option to avoid stopping a VM after a panic event is received,
by passing:
-action panic=none
in the command line arguments, or during runtime by using an upcoming
QMP command.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
---
include/sysemu/runstate-action.h | 1 +
qapi/run-state.json | 27 ++++++++++++++++++++++++++-
qemu-options.hx | 3 +++
softmmu/runstate-action.c | 17 +++++++++++++++++
softmmu/vl.c | 23 +++++++++++++++++++----
5 files changed, 66 insertions(+), 5 deletions(-)
diff --git a/include/sysemu/runstate-action.h b/include/sysemu/runstate-action.h
index dba4b85..cfc46ec 100644
--- a/include/sysemu/runstate-action.h
+++ b/include/sysemu/runstate-action.h
@@ -14,6 +14,7 @@
/* in softmmu/runstate-action.c */
extern RebootAction reboot_action;
extern ShutdownAction shutdown_action;
+extern PanicAction panic_action;
int process_runstate_actions(void *opaque, QemuOpts *opts, Error **errp);
int runstate_action_parse(QemuOptsList *opts_list, const char *optarg);
diff --git a/qapi/run-state.json b/qapi/run-state.json
index 7d8ce61..03ff78b 100644
--- a/qapi/run-state.json
+++ b/qapi/run-state.json
@@ -337,12 +337,14 @@
#
# @shutdown: Guest shutdown
#
+# @panic: Guest has panicked
+#
# @watchdog: A watchdog device's timer has expired
#
# Since: 6.0
##
{ 'enum': 'RunStateEventType',
- 'data': [ 'reboot', 'shutdown', 'watchdog' ] }
+ 'data': [ 'reboot', 'shutdown', 'panic', 'watchdog' ] }
##
# @RunStateAction:
@@ -358,6 +360,7 @@
'data': {
'reboot': 'RunStateRebootAction',
'shutdown': 'RunStateShutdownAction',
+ 'panic': 'RunStatePanicAction',
'watchdog': 'RunStateWatchdogAction' } }
##
@@ -409,6 +412,28 @@
'data': [ 'poweroff', 'pause' ] }
##
+# @RunStatePanicAction:
+#
+# @action: Action taken by QEMU when guest panicks
+#
+# Since: 6.0
+##
+{ 'struct': 'RunStatePanicAction',
+ 'data': { 'action': 'PanicAction' } }
+
+##
+# @PanicAction:
+#
+# @none: Continue VM execution
+#
+# @pause: Pause the VM
+#
+# Since: 6.0
+##
+{ 'enum': 'PanicAction',
+ 'data': [ 'poweroff', 'pause', 'none' ] }
+
+##
# @RunStateWatchdogAction:
#
# @action: Action taken by QEMU when watchdog device timer expires
diff --git a/qemu-options.hx b/qemu-options.hx
index a0d50f0..9ac5a26 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3899,6 +3899,8 @@ DEF("action", HAS_ARG, QEMU_OPTION_action,
" action when guest reboots [default=none]\n"
"-action shutdown=poweroff|pause\n"
" action when guest shuts down [default=poweroff]\n"
+ "-action panic=poweroff|pause|none\n"
+ " action when guest panics [default=poweroff]\n"
"-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n"
" action when watchdog fires [default=reset]\n",
QEMU_ARCH_ALL)
@@ -3911,6 +3913,7 @@ SRST
Examples:
+ ``-action panic=none``
``-action reboot=shutdown,shutdown=pause``
``-watchdog i6300esb -action watchdog=pause``
diff --git a/softmmu/runstate-action.c b/softmmu/runstate-action.c
index 5eae320..bc30102 100644
--- a/softmmu/runstate-action.c
+++ b/softmmu/runstate-action.c
@@ -15,6 +15,7 @@
RebootAction reboot_action = REBOOT_ACTION_NONE;
ShutdownAction shutdown_action = SHUTDOWN_ACTION_POWEROFF;
+PanicAction panic_action = PANIC_ACTION_POWEROFF;
static void runstate_action_help(void)
{
@@ -27,6 +28,18 @@ static void runstate_action_help(void)
}
/*
+ * When -no-shutdown is requested either explicitly or by using its equivalent
+ * -action option, the request should be honored even if a panic occurs.
+ */
+static void fix_panic_action(void)
+{
+ if (shutdown_action == SHUTDOWN_ACTION_PAUSE &&
+ panic_action == PANIC_ACTION_POWEROFF) {
+ panic_action = PANIC_ACTION_PAUSE;
+ }
+}
+
+/*
* Process an event|action pair and set the appropriate internal
* state if event and action are valid.
*/
@@ -45,6 +58,10 @@ static int set_runstate_action(void *opaque, const char
*event,
case RUN_STATE_EVENT_TYPE_SHUTDOWN:
shutdown_action = qapi_enum_parse(&ShutdownAction_lookup,
action, -1, errp);
+ fix_panic_action();
+ break;
+ case RUN_STATE_EVENT_TYPE_PANIC:
+ panic_action = qapi_enum_parse(&PanicAction_lookup, action, -1, errp);
break;
case RUN_STATE_EVENT_TYPE_WATCHDOG:
if (select_watchdog_action(action) == -1) {
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 35575a1..2ff0291 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -1447,10 +1447,21 @@ void qemu_system_guest_panicked(GuestPanicInformation
*info)
if (current_cpu) {
current_cpu->crash_occurred = true;
}
- qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_PAUSE,
- !!info, info);
- vm_stop(RUN_STATE_GUEST_PANICKED);
- if (shutdown_action == SHUTDOWN_ACTION_POWEROFF) {
+ /*
+ * TODO: Currently the available panic actions are: none, pause, and
+ * poweroff, but in principle debug and reset could be supported as well.
+ * Investigate any potential use cases for the unimplemented actions.
+ */
+ if (panic_action != PANIC_ACTION_NONE) {
+ qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_PAUSE,
+ !!info, info);
+ vm_stop(RUN_STATE_GUEST_PANICKED);
+ } else {
+ qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_RUN,
+ !!info, info);
+ }
+
+ if (panic_action == PANIC_ACTION_POWEROFF) {
qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_POWEROFF,
!!info, info);
qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_PANIC);
@@ -3591,6 +3602,10 @@ void qemu_init(int argc, char **argv, char **envp)
break;
case QEMU_OPTION_no_shutdown:
shutdown_action = SHUTDOWN_ACTION_PAUSE;
+ /* no_shutdown is requested, also honor it if guest panics */
+ if (panic_action == PANIC_ACTION_POWEROFF) {
+ panic_action = PANIC_ACTION_PAUSE;
+ }
break;
case QEMU_OPTION_show_cursor:
warn_report("The -show-cursor option is deprecated. Please "
--
1.8.3.1