Re: [Qemu-devel] pause_all_vcpus() TCG bug?

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2013-05-01 15:47, Peter Maydell wrote:
> On 1 May 2013 14:33, Andreas Färber <afaerber@suse.de> wrote:
>> Hello,
>>
>> This is today's function, with annotations and question inline:
>>
>> void pause_all_vcpus(void)
>> {
>>     CPUArchState *penv = first_cpu;
>>
>>     qemu_clock_enable(vm_clock, false);
>>     while (penv) {
>>         CPUState *pcpu = ENV_GET_CPU(penv);
>>         pcpu->stop = true;
>>         qemu_cpu_kick(pcpu);
>>         penv = penv->next_cpu;
>>     }
>>
>> /* So, at this point penv == NULL. */
>>
>>     if (qemu_in_vcpu_thread()) {
>>         cpu_stop_current();
>>         if (!kvm_enabled()) {
>>             while (penv) {
>>
>> /* Looks like this can never be true then? */
>> /* Is penv = first_cpu; missing? */

Yeah, obviously. It practically didn't matter so far for the use case of
pause/resume_all_vcpus over a vcpu itself (kvmvapic). Feel free to fix.

>>
>>                 CPUState *pcpu = ENV_GET_CPU(penv);
>>                 pcpu->stop = 0;
>>
>> /* 0 instead of false may hint at a mismerge... */

Nope, stop was uint32_t at that time.

Jan

>>
>>                 pcpu->stopped = true;
>>                 penv = penv->next_cpu;
>>             }
>>             return;
>>         }
>>     }
> 
> This certainly looks odd. This bug seems to have
> been present since this patch was first committed
> (d798e9745, January last year, by Jan.)
> 
> -- PMM
> 

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