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Re: [Qemu-devel] [PATCH v2 1/2] move vm_start to cpus.c
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/2] move vm_start to cpus.c |
Date: |
Fri, 27 Jan 2017 17:05:54 +0000 |
User-agent: |
mu4e 0.9.19; emacs 25.1.91.4 |
Claudio Imbrenda <address@hidden> writes:
> On 27/01/17 17:31, Alex Bennée wrote:
>>
>> Claudio Imbrenda <address@hidden> writes:
>>
>>> This patch:
>>>
>>> * moves vm_start to cpus.c .
>>> * exports qemu_vmstop_requested, since it's needed by vm_start .
>>> * extracts vm_prepare_start from vm_start; it does what vm_start did,
>>> except restarting the cpus. vm_start now calls vm_prepare_start.
>>> * moves the call to qemu_clock_enable away from resume_all_vcpus, and
>>> add an explicit call to it before each instance of resume_all_vcpus
>>> in the code.
>>
>> Can you be a bit more explicit about this? Shouldn't CPU time still
>> accrue even if you are only starting some of them?
>
> This is what's happening in the newest version of this patch, which I
> sent around yesterday, although I forgot to update the patch
> description; I'll send a fixed version ASAP.
>
>> I'd prefer making resume_all_vcpus() a private function called from
>
> resume_all_vcpus is already being used in other files too, doesn't make
> sense to make it private now.
Yeah I would rename the call-sites across QEMU. Perhaps just one entry
point of rename_vcpus() which does the right thing given a list or NULL.
But pushing the details of restarting the timer to the call sites just
sounds like a way of it getting missed next time someone adds a resume
somewhere.
>
>> resume_some_vcpus() which can then make the QEMU_CLOCK_VIRTUAL decision
>> in one place - with a comment.
>>
>>> * adds resume_some_vcpus, to selectively restart only some CPUs.
>>>
>>> Signed-off-by: Claudio Imbrenda <address@hidden>
>>> ---
>>> cpus.c | 61
>>> +++++++++++++++++++++++++++++++++++++++++++++-
>>> hw/i386/kvmvapic.c | 2 ++
>>> include/sysemu/cpus.h | 1 +
>>> include/sysemu/sysemu.h | 2 ++
>>> target-s390x/misc_helper.c | 2 ++
>>> vl.c | 32 +++---------------------
>>> 6 files changed, 70 insertions(+), 30 deletions(-)
>>>
>>> diff --git a/cpus.c b/cpus.c
>>> index 31204bb..c102624 100644
>>> --- a/cpus.c
>>> +++ b/cpus.c
>>> @@ -1260,12 +1260,28 @@ void resume_all_vcpus(void)
>>> {
>>> CPUState *cpu;
>>>
>>> - qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
>>> CPU_FOREACH(cpu) {
>>> cpu_resume(cpu);
>>> }
>>> }
>>>
>>> +/**
>>> + * resume_some_vcpus - resumes some vCPUs, indicated in a NULL-terminated
>>> + * array of CPUState *; if the parameter is NULL, all CPUs are resumed.
>>> + */
>>> +void resume_some_vcpus(CPUState **cpus)
>>> +{
>>> + int idx;
>>> +
>>> + if (!cpus) {
>>> + resume_all_vcpus();
>>> + return;
>>> + }
>>> + for (idx = 0; cpus[idx]; idx++) {
>>> + cpu_resume(cpus[idx]);
>>> + }
>>> +}
>>> +
>>> void cpu_remove(CPUState *cpu)
>>> {
>>> cpu->stop = true;
>>> @@ -1396,6 +1412,49 @@ int vm_stop(RunState state)
>>> return do_vm_stop(state);
>>> }
>>>
>>> +/**
>>> + * Prepare for (re)starting the VM.
>>> + * Returns -1 if the vCPUs are not to be restarted (e.g. if they are
>>> already
>>> + * running or in case of an error condition), 0 otherwise.
>>> + */
>>> +int vm_prepare_start(void)
>>> +{
>>> + RunState requested;
>>> + int res = 0;
>>> +
>>> + qemu_vmstop_requested(&requested);
>>> + if (runstate_is_running() && requested == RUN_STATE__MAX) {
>>> + return -1;
>>> + }
>>> +
>>> + /* Ensure that a STOP/RESUME pair of events is emitted if a
>>> + * vmstop request was pending. The BLOCK_IO_ERROR event, for
>>> + * example, according to documentation is always followed by
>>> + * the STOP event.
>>> + */
>>> + if (runstate_is_running()) {
>>> + qapi_event_send_stop(&error_abort);
>>> + res = -1;
>>> + } else {
>>> + replay_enable_events();
>>> + cpu_enable_ticks();
>>> + runstate_set(RUN_STATE_RUNNING);
>>> + vm_state_notify(1, RUN_STATE_RUNNING);
>>> + }
>>> +
>>> + /* XXX: is it ok to send this even before actually resuming the CPUs?
>>> */
>>> + qapi_event_send_resume(&error_abort);
>>> + return res;
>>> +}
>>> +
>>> +void vm_start(void)
>>> +{
>>> + if (!vm_prepare_start()) {
>>> + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
>>> + resume_all_vcpus();
>>> + }
>>> +}
>>> +
>>> /* does a state transition even if the VM is already stopped,
>>> current state is forgotten forever */
>>> int vm_stop_force_state(RunState state)
>>> diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c
>>> index 74a549b..3101860 100644
>>> --- a/hw/i386/kvmvapic.c
>>> +++ b/hw/i386/kvmvapic.c
>>> @@ -446,6 +446,7 @@ static void patch_instruction(VAPICROMState *s, X86CPU
>>> *cpu, target_ulong ip)
>>> abort();
>>> }
>>>
>>> + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
>>> resume_all_vcpus();
>>>
>>> if (!kvm_enabled()) {
>>> @@ -686,6 +687,7 @@ static void vapic_write(void *opaque, hwaddr addr,
>>> uint64_t data,
>>> pause_all_vcpus();
>>> patch_byte(cpu, env->eip - 2, 0x66);
>>> patch_byte(cpu, env->eip - 1, 0x90);
>>> + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
>>> resume_all_vcpus();
>>> }
>>>
>>> diff --git a/include/sysemu/cpus.h b/include/sysemu/cpus.h
>>> index 3728a1e..5fa074b 100644
>>> --- a/include/sysemu/cpus.h
>>> +++ b/include/sysemu/cpus.h
>>> @@ -5,6 +5,7 @@
>>> bool qemu_in_vcpu_thread(void);
>>> void qemu_init_cpu_loop(void);
>>> void resume_all_vcpus(void);
>>> +void resume_some_vcpus(CPUState **cpus);
>>> void pause_all_vcpus(void);
>>> void cpu_stop_current(void);
>>> void cpu_ticks_init(void);
>>> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
>>> index ef2c50b..ac301d6 100644
>>> --- a/include/sysemu/sysemu.h
>>> +++ b/include/sysemu/sysemu.h
>>> @@ -37,6 +37,7 @@ void vm_state_notify(int running, RunState state);
>>> #define VMRESET_REPORT true
>>>
>>> void vm_start(void);
>>> +int vm_prepare_start(void);
>>> int vm_stop(RunState state);
>>> int vm_stop_force_state(RunState state);
>>>
>>> @@ -60,6 +61,7 @@ void qemu_register_powerdown_notifier(Notifier *notifier);
>>> void qemu_system_debug_request(void);
>>> void qemu_system_vmstop_request(RunState reason);
>>> void qemu_system_vmstop_request_prepare(void);
>>> +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);
>>> diff --git a/target-s390x/misc_helper.c b/target-s390x/misc_helper.c
>>> index 4df2ec6..2b74710 100644
>>> --- a/target-s390x/misc_helper.c
>>> +++ b/target-s390x/misc_helper.c
>>> @@ -133,6 +133,7 @@ static int modified_clear_reset(S390CPU *cpu)
>>> s390_crypto_reset();
>>> scc->load_normal(CPU(cpu));
>>> cpu_synchronize_all_post_reset();
>>> + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
>>> resume_all_vcpus();
>>> return 0;
>>> }
>>> @@ -152,6 +153,7 @@ static int load_normal_reset(S390CPU *cpu)
>>> scc->initial_cpu_reset(CPU(cpu));
>>> scc->load_normal(CPU(cpu));
>>> cpu_synchronize_all_post_reset();
>>> + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
>>> resume_all_vcpus();
>>> return 0;
>>> }
>>> diff --git a/vl.c b/vl.c
>>> index f3abd99..42addbb 100644
>>> --- a/vl.c
>>> +++ b/vl.c
>>> @@ -746,7 +746,7 @@ StatusInfo *qmp_query_status(Error **errp)
>>> return info;
>>> }
>>>
>>> -static bool qemu_vmstop_requested(RunState *r)
>>> +bool qemu_vmstop_requested(RunState *r)
>>> {
>>> qemu_mutex_lock(&vmstop_lock);
>>> *r = vmstop_requested;
>>> @@ -767,34 +767,6 @@ void qemu_system_vmstop_request(RunState state)
>>> qemu_notify_event();
>>> }
>>>
>>> -void vm_start(void)
>>> -{
>>> - RunState requested;
>>> -
>>> - qemu_vmstop_requested(&requested);
>>> - if (runstate_is_running() && requested == RUN_STATE__MAX) {
>>> - return;
>>> - }
>>> -
>>> - /* Ensure that a STOP/RESUME pair of events is emitted if a
>>> - * vmstop request was pending. The BLOCK_IO_ERROR event, for
>>> - * example, according to documentation is always followed by
>>> - * the STOP event.
>>> - */
>>> - if (runstate_is_running()) {
>>> - qapi_event_send_stop(&error_abort);
>>> - } else {
>>> - replay_enable_events();
>>> - cpu_enable_ticks();
>>> - runstate_set(RUN_STATE_RUNNING);
>>> - vm_state_notify(1, RUN_STATE_RUNNING);
>>> - resume_all_vcpus();
>>> - }
>>> -
>>> - qapi_event_send_resume(&error_abort);
>>> -}
>>> -
>>> -
>>> /***********************************************************/
>>> /* real time host monotonic timer */
>>>
>>> @@ -1910,6 +1882,7 @@ static bool main_loop_should_exit(void)
>>> if (qemu_reset_requested()) {
>>> pause_all_vcpus();
>>> qemu_system_reset(VMRESET_REPORT);
>>> + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
>>> resume_all_vcpus();
>>> if (!runstate_check(RUN_STATE_RUNNING) &&
>>> !runstate_check(RUN_STATE_INMIGRATE)) {
>>> @@ -1921,6 +1894,7 @@ static bool main_loop_should_exit(void)
>>> qemu_system_reset(VMRESET_SILENT);
>>> notifier_list_notify(&wakeup_notifiers, &wakeup_reason);
>>> wakeup_reason = QEMU_WAKEUP_REASON_NONE;
>>> + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
>>> resume_all_vcpus();
>>> qapi_event_send_wakeup(&error_abort);
>>> }
>>
>>
>> --
>> Alex Bennée
>>
--
Alex Bennée