2017-12-13 18:20 GMT+08:00 David Hildenbrand <david@xxxxxxxxxx>:
> On 13.12.2017 02:33, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
>>
>> This patch reuses the preempted field in kvm_steal_time, and will export
>> the vcpu running/pre-empted information to the guest from host. This will
>> enable guest to intelligently send ipi to running vcpus and set flag for
>> pre-empted vcpus. This will prevent waiting for vcpus that are not running.
>>
>> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
>> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
>> Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
>> ---
>> arch/x86/include/uapi/asm/kvm_para.h | 3 +++
>> arch/x86/kernel/kvm.c | 2 +-
>> arch/x86/kvm/x86.c | 4 ++--
>> 3 files changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
>> index 09cc064..763b692 100644
>> --- a/arch/x86/include/uapi/asm/kvm_para.h
>> +++ b/arch/x86/include/uapi/asm/kvm_para.h
>> @@ -51,6 +51,9 @@ struct kvm_steal_time {
>> __u32 pad[11];
>> };
>>
>> +#define KVM_VCPU_NOT_PREEMPTED (0 << 0)
>> +#define KVM_VCPU_PREEMPTED (1 << 0)
>
> Is it really helpful to have two flags?
>
> Just use KVM_VCPU_PREEMPTED and clear that one in record_steal_time()
I think it is fine since there is a third flag introduced in patch
2/4, it is more clear currently.
Regards,
Wanpeng Li
