Re: [PATCH V5 01/12] cpus: refactor vm_stop

[Steven Sistare]

On 11/20/2023 8:22 AM, Fabiano Rosas wrote:
> Steve Sistare <steven.sistare@oracle.com> writes:
>> Refactor the vm_stop functions into one common subroutine do_vm_stop called
>> with options.  No functional change.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
>> ---
>>  system/cpus.c | 44 +++++++++++++++++---------------------------
>>  1 file changed, 17 insertions(+), 27 deletions(-)
>>
>> diff --git a/system/cpus.c b/system/cpus.c
>> index 0848e0d..f72c4be 100644
>> --- a/system/cpus.c
>> +++ b/system/cpus.c
>> @@ -252,10 +252,21 @@ void cpu_interrupt(CPUState *cpu, int mask)
>>      }
>>  }
>>  
>> -static int do_vm_stop(RunState state, bool send_stop)
>> +static int do_vm_stop(RunState state, bool send_stop, bool force)
>>  {
>>      int ret = 0;
>>  
>> +    if (qemu_in_vcpu_thread()) {
>> +        qemu_system_vmstop_request_prepare();
>> +        qemu_system_vmstop_request(state);
>> +        /*
>> +         * FIXME: should not return to device code in case
>> +         * vm_stop() has been requested.
>> +         */
>> +        cpu_stop_current();
>> +        return 0;
>> +    }
> 
> At vm_stop_force_state(), this block used to be under
> runstate_is_running(), but now it runs unconditionally.

vm_stop_force_state callers should never be called in a vcpu thread, so this 
block
is never executed for them.  I could assert that.

> At vm_shutdown(), this block was not executed at all, but now it is.

vm_shutdown should never be called from a vcpu thread.
I could assert that.

- Steve

> We might need some words to explain why this patch doesn't affect
> functionality.
>> +
>>      if (runstate_is_running()) {
>>          runstate_set(state);
>>          cpu_disable_ticks();
>> @@ -264,6 +275,8 @@ static int do_vm_stop(RunState state, bool send_stop)
>>          if (send_stop) {
>>              qapi_event_send_stop();
>>          }
>> +    } else if (force) {
>> +        runstate_set(state);
>>      }
>>  
>>      bdrv_drain_all();
>> @@ -278,7 +291,7 @@ static int do_vm_stop(RunState state, bool send_stop)
>>   */
>>  int vm_shutdown(void)
>>  {
>> -    return do_vm_stop(RUN_STATE_SHUTDOWN, false);
>> +    return do_vm_stop(RUN_STATE_SHUTDOWN, false, false);
>>  }
>>  
>>  bool cpu_can_run(CPUState *cpu)
>> @@ -656,18 +669,7 @@ void cpu_stop_current(void)
>>  
>>  int vm_stop(RunState state)
>>  {
>> -    if (qemu_in_vcpu_thread()) {
>> -        qemu_system_vmstop_request_prepare();
>> -        qemu_system_vmstop_request(state);
>> -        /*
>> -         * FIXME: should not return to device code in case
>> -         * vm_stop() has been requested.
>> -         */
>> -        cpu_stop_current();
>> -        return 0;
>> -    }
>> -
>> -    return do_vm_stop(state, true);
>> +    return do_vm_stop(state, true, false);
>>  }
>>  
>>  /**
>> @@ -723,19 +725,7 @@ void vm_start(void)
>>     current state is forgotten forever */
>>  int vm_stop_force_state(RunState state)
>>  {
>> -    if (runstate_is_running()) {
>> -        return vm_stop(state);
>> -    } else {
>> -        int ret;
>> -        runstate_set(state);
>> -
>> -        bdrv_drain_all();
>> -        /* Make sure to return an error if the flush in a previous vm_stop()
>> -         * failed. */
>> -        ret = bdrv_flush_all();
>> -        trace_vm_stop_flush_all(ret);
>> -        return ret;
>> -    }
>> +    return do_vm_stop(state, true, true);
>>  }
>>  
>>  void qmp_memsave(int64_t addr, int64_t size, const char *filename,