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Re: [Qemu-devel] [PATCH v2 1/2] move vm_start to cpus.c
From: |
Claudio Imbrenda |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/2] move vm_start to cpus.c |
Date: |
Fri, 27 Jan 2017 17:54:28 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 |
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.
> 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
>