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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [Qemu-devel] [PATCH v5 2/4] shutdown: Prepare for use of an enum in reset/shutdown_request
Eric Blake <eblake@xxxxxxxxxx> writes:
> We want to track why a guest was shutdown; in particular, being able
> to tell the difference between a guest request (such as ACPI request)
> and host request (such as SIGINT) will prove useful to libvirt.
> Since all requests eventually end up changing shutdown_requested in
> vl.c, the logical change is to make that value track the reason,
> rather than its current 0/1 contents.
>
> Since command-line options control whether a reset request is turned
> into a shutdown request instead, the same treatment is given to
> reset_requested.
>
> This patch adds a QAPI enum ShutdownCause that describes reasons
> that a shutdown can be requested, and changes qemu_system_reset() to
> pass the reason through, although for now it is not reported. The
> next patch will actually wire things up to modify events to report
> data based on the reason, and to pass the correct enum value in from
> various call-sites that can trigger a reset/shutdown. Since QAPI
> generates enums starting at 0, it's easier if we use a different
> number as our sentinel that no request has happened yet. Most of
> the changes are in vl.c, but xen was using things externally.
>
> Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
>
> ---
> v4: s/ShutdownType/ShutdownCause/, no thanks to mingw header pollution
> v3: new patch
> ---
> qapi-schema.json | 23 +++++++++++++++++++++++
> include/sysemu/sysemu.h | 2 +-
> vl.c | 44 ++++++++++++++++++++++++++++----------------
> hw/i386/xen/xen-hvm.c | 9 ++++++---
> migration/colo.c | 2 +-
> migration/savevm.c | 2 +-
> 6 files changed, 60 insertions(+), 22 deletions(-)
>
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 01b087f..a4ebdd1 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -2304,6 +2304,29 @@
> { 'command': 'system_powerdown' }
>
> ##
> +# @ShutdownCause:
> +#
> +# Enumeration of various causes for shutdown.
> +#
> +# @host-qmp: Reaction to a QMP command, such as 'quit'
> +# @host-signal: Reaction to a signal, such as SIGINT
> +# @host-ui: Reaction to a UI event, such as closing the window
> +# @host-replay: The host is replaying an earlier shutdown event
> +# @host-error: Qemu encountered an error that prevents further use of the
> guest
> +# @guest-shutdown: The guest requested a shutdown, such as via ACPI or
> +# other hardware-specific action
> +# @guest-reset: The guest requested a reset, and the command line
> +# response to a reset is to instead trigger a shutdown
> +# @guest-panic: The guest panicked, and the command line response to
> +# a panic is to trigger a shutdown
> +#
> +# Since: 2.10
> +##
> +{ 'enum': 'ShutdownCause',
> + 'data': [ 'host-qmp', 'host-signal', 'host-ui', 'host-replay',
> 'host-error',
> + 'guest-shutdown', 'guest-reset', 'guest-panic' ] }
> +
> +##
> # @cpu:
> #
> # This command is a nop that is only provided for the purposes of
> compatibility.
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index 16175f7..00a907f 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -65,7 +65,7 @@ bool qemu_vmstop_requested(RunState *r);
> int qemu_shutdown_requested_get(void);
> int qemu_reset_requested_get(void);
> void qemu_system_killed(int signal, pid_t pid);
> -void qemu_system_reset(bool report);
> +void qemu_system_reset(bool report, int reason);
> void qemu_system_guest_panicked(GuestPanicInformation *info);
> size_t qemu_target_page_size(void);
>
> diff --git a/vl.c b/vl.c
> index 879786a..2b95b7f 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1597,8 +1597,8 @@ void vm_state_notify(int running, RunState state)
> }
> }
>
> -static int reset_requested;
> -static int shutdown_requested, shutdown_signal;
> +static int reset_requested = -1;
> +static int shutdown_requested = -1, shutdown_signal;
Peeking ahead, I see that shutdown_requested and reset_requested take
ShutdownCause values and -1. The latter means "no shutdown requested".
What about adding 'none' to ShutdownCause, with value 0, und use that
instead of literal -1? Would avoid the unusual "negative means false,
non-negative means true".
PATCH 4 exposes ShutdownCause in event SHUTDOWN, and 'none' must not
occur there. However, if we ever add a query-shutdown to go with this
event, we will need 'none' there.
I'd be tempted to reshuffle declarations here, because shutdown_signal's
int is a different one than reset_requested's and shutdown_requested,
and the latter two's "negative means false, non-negative means true" is
unusual enough to justify a comment.
> static pid_t shutdown_pid;
> static int powerdown_requested;
> static int debug_requested;
> @@ -1624,7 +1624,7 @@ int qemu_reset_requested_get(void)
>
> static int qemu_shutdown_requested(void)
> {
> - return atomic_xchg(&shutdown_requested, 0);
> + return atomic_xchg(&shutdown_requested, -1);
> }
Hmm. In case we stick to literal -1: consider splitting this patch into
a part that changes @shutdown_requested from zero/non-zero to
negative/non-negative, and a part that uses ShutdownCause for the
non-negative values.
>
> static void qemu_kill_report(void)
> @@ -1650,11 +1650,11 @@ static void qemu_kill_report(void)
> static int qemu_reset_requested(void)
> {
> int r = reset_requested;
> - if (r && replay_checkpoint(CHECKPOINT_RESET_REQUESTED)) {
> - reset_requested = 0;
> + if (r >= 0 && replay_checkpoint(CHECKPOINT_RESET_REQUESTED)) {
> + reset_requested = -1;
> return r;
> }
> - return false;
> + return -1;
"return false" in a function returning int smells, good riddance.
> }
>
> static int qemu_suspend_requested(void)
> @@ -1686,7 +1686,12 @@ static int qemu_debug_requested(void)
> return r;
> }
>
> -void qemu_system_reset(bool report)
> +/*
> + * Reset the VM. If @report is VMRESET_REPORT, issue an event, using
> + * the @reason interpreted as ShutdownType for details. Otherwise,
> + * @report is VMRESET_SILENT and @reason is ignored.
> + */
> +void qemu_system_reset(bool report, int reason)
Why int reason and not ShutdownCause? Hmm, peeking ahead, I see you
pass -1 with VMRESET_SILENT. Yet another place where you use int for
type ShutdownCause + { -1 }. Adding 'none' to ShutdownCause looks
even more attractive to me now.
> {
> MachineClass *mc;
>
> @@ -1700,6 +1705,7 @@ void qemu_system_reset(bool report)
> qemu_devices_reset();
> }
> if (report) {
> + assert(reason >= 0);
> qapi_event_send_reset(&error_abort);
> }
> cpu_synchronize_all_post_reset();
> @@ -1738,9 +1744,10 @@ void qemu_system_guest_panicked(GuestPanicInformation
> *info)
> void qemu_system_reset_request(void)
> {
> if (no_reboot) {
> - shutdown_requested = 1;
> + /* FIXME - add a parameter to allow callers to specify reason */
FIXME addressed in the next patch. Mention in this one's commit
message?
> + shutdown_requested = SHUTDOWN_CAUSE_GUEST_RESET;
> } else {
> - reset_requested = 1;
> + reset_requested = SHUTDOWN_CAUSE_GUEST_RESET;
> }
> cpu_stop_current();
> qemu_notify_event();
> @@ -1807,7 +1814,7 @@ void qemu_system_killed(int signal, pid_t pid)
> /* Cannot call qemu_system_shutdown_request directly because
> * we are in a signal handler.
> */
> - shutdown_requested = 1;
> + shutdown_requested = SHUTDOWN_CAUSE_HOST_SIGNAL;
> qemu_notify_event();
> }
>
> @@ -1815,7 +1822,8 @@ void qemu_system_shutdown_request(void)
> {
> trace_qemu_system_shutdown_request();
> replay_shutdown_request();
> - shutdown_requested = 1;
> + /* FIXME - add a parameter to allow callers to specify reason */
Likewise.
> + shutdown_requested = SHUTDOWN_CAUSE_GUEST_SHUTDOWN;
> qemu_notify_event();
> }
>
> @@ -1846,13 +1854,16 @@ void qemu_system_debug_request(void)
> static bool main_loop_should_exit(void)
> {
> RunState r;
> + int request;
> +
> if (qemu_debug_requested()) {
> vm_stop(RUN_STATE_DEBUG);
> }
> if (qemu_suspend_requested()) {
> qemu_system_suspend();
> }
> - if (qemu_shutdown_requested()) {
> + request = qemu_shutdown_requested();
> + if (request >= 0) {
> qemu_kill_report();
> qapi_event_send_shutdown(&error_abort);
> if (no_shutdown) {
> @@ -1861,9 +1872,10 @@ static bool main_loop_should_exit(void)
> return true;
> }
> }
> - if (qemu_reset_requested()) {
> + request = qemu_reset_requested();
> + if (request >= 0) {
> pause_all_vcpus();
> - qemu_system_reset(VMRESET_REPORT);
> + qemu_system_reset(VMRESET_REPORT, request);
> resume_all_vcpus();
> if (!runstate_check(RUN_STATE_RUNNING) &&
> !runstate_check(RUN_STATE_INMIGRATE)) {
> @@ -1872,7 +1884,7 @@ static bool main_loop_should_exit(void)
> }
> if (qemu_wakeup_requested()) {
> pause_all_vcpus();
> - qemu_system_reset(VMRESET_SILENT);
> + qemu_system_reset(VMRESET_SILENT, -1);
> notifier_list_notify(&wakeup_notifiers, &wakeup_reason);
> wakeup_reason = QEMU_WAKEUP_REASON_NONE;
> resume_all_vcpus();
> @@ -4684,7 +4696,7 @@ int main(int argc, char **argv, char **envp)
> reading from the other reads, because timer polling functions query
> clock values from the log. */
> replay_checkpoint(CHECKPOINT_RESET);
> - qemu_system_reset(VMRESET_SILENT);
> + qemu_system_reset(VMRESET_SILENT, -1);
> register_global_state();
> if (replay_mode != REPLAY_MODE_NONE) {
> replay_vmstate_init();
> diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
> index b1c05ff..3a6484c 100644
> --- a/hw/i386/xen/xen-hvm.c
> +++ b/hw/i386/xen/xen-hvm.c
> @@ -1089,11 +1089,14 @@ static void cpu_handle_ioreq(void *opaque)
> * causes Xen to powerdown the domain.
> */
> if (runstate_is_running()) {
> - if (qemu_shutdown_requested_get()) {
> + int request;
> +
> + if (qemu_shutdown_requested_get() >= 0) {
> destroy_hvm_domain(false);
> }
> - if (qemu_reset_requested_get()) {
> - qemu_system_reset(VMRESET_REPORT);
> + request = qemu_reset_requested_get();
> + if (request >= 0) {
> + qemu_system_reset(VMRESET_REPORT, request);
> destroy_hvm_domain(true);
> }
> }
> diff --git a/migration/colo.c b/migration/colo.c
> index c19eb3f..17a5482 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -611,7 +611,7 @@ void *colo_process_incoming_thread(void *opaque)
> }
>
> qemu_mutex_lock_iothread();
> - qemu_system_reset(VMRESET_SILENT);
> + qemu_system_reset(VMRESET_SILENT, -1);
> vmstate_loading = true;
> if (qemu_loadvm_state(fb) < 0) {
> error_report("COLO: loadvm failed");
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 03ae1bd..dcbaf00 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2292,7 +2292,7 @@ int load_vmstate(const char *name)
> return -EINVAL;
> }
>
> - qemu_system_reset(VMRESET_SILENT);
> + qemu_system_reset(VMRESET_SILENT, -1);
> mis->from_src_file = f;
>
> aio_context_acquire(aio_context);
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