Re: [PATCH v8 1/4] KVM: X86: Add vCPU running/preempted state

[David Hildenbrand <david@redhat.com>]

On 13.12.2017 02:33, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
> 
> 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@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
> ---
>  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()


-- 

Thanks,

David / dhildenb