Re: [PATCH 17/22] kvm: Move irqchip event processing out of inner loop

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

On 2011-01-31 11:08, Avi Kivity wrote:
> On 01/27/2011 03:10 PM, Jan Kiszka wrote:
>> Align with qemu-kvm and prepare for IO exit fix: There is no need to run
>> kvm_arch_process_irqchip_events in the inner VCPU loop. Any state change
>> this service processes will first cause an exit from kvm_cpu_exec
>> anyway. And we will have to reenter the kernel on IO exits
>> unconditionally, something that the current logic prevents.
>>
>> Signed-off-by: Jan Kiszka<jan.kiszka@siemens.com>
>> ---
>>   kvm-all.c |   11 ++++++-----
>>   1 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/kvm-all.c b/kvm-all.c
>> index 5bfa8c0..46ecc1c 100644
>> --- a/kvm-all.c
>> +++ b/kvm-all.c
>> @@ -892,6 +892,12 @@ int kvm_cpu_exec(CPUState *env)
>>
>>       DPRINTF("kvm_cpu_exec()\n");
>>
>> +    if (kvm_arch_process_irqchip_events(env)) {
>> +        env->exit_request = 0;
>> +        env->exception_index = EXCP_HLT;
>> +        return 0;
>> +    }
>> +
>>       do {
>>   #ifndef CONFIG_IOTHREAD
>>           if (env->exit_request) {
>> @@ -901,11 +907,6 @@ int kvm_cpu_exec(CPUState *env)
>>           }
> 
> We check for ->exit_request here
> 
>>   #endif
>>
>> -        if (kvm_arch_process_irqchip_events(env)) {
>> -            ret = 0;
>> -            break;
>> -        }
>> -
> 
> But this checks for ->interrupt_request.  What ensures that we exit when 
> ->interrupt_request is set?

Good question, need to check again. But if that turns out to be an
issue, qemu-kvm would be broken as well. I'm just aligning the code here.

Jan

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