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vl: Add option to avoid stopping VM upon guest panic 

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>
Message-Id: <1607705564-26264-3-git-send-email-alejandro.j.jimenez@oracle.com>
[Do not fix panic action in the variable, instead modify -no-shutdown. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Alejandro Jimenez 2020-12-11 17:31:52 -05:00 committed by Paolo Bonzini
parent 2a5ad60b54
commit c753e8e725
6 changed files with 43 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/sysemu/runstate-action.h
View File

@ -14,5 +14,6 @@
/* in softmmu/runstate-action.c */
extern RebootAction reboot_action;
extern ShutdownAction shutdown_action;
extern PanicAction panic_action;
#endif /* RUNSTATE_ACTION_H */

16
qapi/run-state.json
View File

@ -353,6 +353,18 @@
{ 'enum': 'ShutdownAction',
'data': [ 'poweroff', 'pause' ] }
##
# @PanicAction:
#
# @none: Continue VM execution
#
# @pause: Pause the VM
#
# Since: 6.0
##
{ 'enum': 'PanicAction',
'data': [ 'poweroff', 'pause', 'none' ] }
##
# @watchdog-set-action:
#
@ -372,6 +384,8 @@
#
# @shutdown: @ShutdownAction action taken on guest shutdown.
#
# @panic: @PanicAction action taken on guest panic.
#
# @watchdog: @WatchdogAction action taken when watchdog timer expires .
#
# Returns: Nothing on success.
@ -383,12 +397,14 @@
# -> { "execute": "set-action",
# "arguments": { "reboot": "shutdown",
# "shutdown" : "pause",
# "panic": "pause",
# "watchdog": "inject-nmi" } }
# <- { "return": {} }
##
{ 'command': 'set-action',
'data': { '*reboot': 'RebootAction',
'*shutdown': 'ShutdownAction',
'*panic': 'PanicAction',
'*watchdog': 'WatchdogAction' },
'allow-preconfig': true }

3
qemu-options.hx
View File

@ -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``

5
softmmu/runstate-action.c
View File

@ -15,6 +15,7 @@
RebootAction reboot_action = REBOOT_ACTION_NONE;
ShutdownAction shutdown_action = SHUTDOWN_ACTION_POWEROFF;
PanicAction panic_action = PANIC_ACTION_POWEROFF;
/*
* Receives actions to be applied for specific guest events
@ -30,6 +31,10 @@ void qmp_set_action(bool has_reboot, RebootAction reboot,
reboot_action = reboot;
}
if (has_panic) {
panic_action = panic;
}
if (has_watchdog) {
qmp_watchdog_set_action(watchdog, errp);
}

18
softmmu/runstate.c
View File

@ -469,13 +469,23 @@ 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_PAUSE) {
qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_PAUSE,
!!info, info);
vm_stop(RUN_STATE_GUEST_PANICKED);
} else if (panic_action == PANIC_ACTION_POWEROFF) {
qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_POWEROFF,
!!info, info);
vm_stop(RUN_STATE_GUEST_PANICKED);
qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_PANIC);
} else {
qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_RUN,
!!info, info);
}
if (info) {

5
softmmu/vl.c
View File

@ -489,6 +489,9 @@ static QemuOptsList qemu_action_opts = {
},{
.name = "reboot",
.type = QEMU_OPT_STRING,
},{
.name = "panic",
.type = QEMU_OPT_STRING,
},{
.name = "watchdog",
.type = QEMU_OPT_STRING,
@ -3212,7 +3215,7 @@ void qemu_init(int argc, char **argv, char **envp)
break;
case QEMU_OPTION_no_shutdown:
olist = qemu_find_opts("action");
qemu_opts_parse_noisily(olist, "shutdown=pause", false);
qemu_opts_parse_noisily(olist, "panic=pause,shutdown=pause", false);
break;
case QEMU_OPTION_show_cursor:
warn_report("The -show-cursor option is deprecated. Please "