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Subject: Re: [PATCH v2 2/2] KVM:390: Use kvm_vcpu_wake_up in
 kvm_s390_vcpu_wakeup
To:     Wanpeng Li <kernellwp@gmail.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Michael Mueller <mimu@linux.ibm.com>
References: <1563449947-7749-1-git-send-email-wanpengli@tencent.com>
 <1563449947-7749-2-git-send-email-wanpengli@tencent.com>
From:   Christian Borntraeger <borntraeger@de.ibm.com>
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Date:   Thu, 18 Jul 2019 14:09:13 +0200
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On 18.07.19 13:39, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
> 
> Use kvm_vcpu_wake_up() in kvm_s390_vcpu_wakeup().
> 
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>

with patch1 this looks good. 
> ---
>  arch/s390/kvm/interrupt.c | 15 +--------------
>  1 file changed, 1 insertion(+), 14 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index 26f8bf4..881cc5a 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -1229,21 +1229,8 @@ void kvm_s390_vcpu_wakeup(struct kvm_vcpu *vcpu)
>  	 * in kvm_vcpu_block without having the waitqueue set (polling)
>  	 */
>  	vcpu->valid_wakeup = true;
> -	/*
> -	 * This is mostly to document, that the read in swait_active could
> -	 * be moved before other stores, leading to subtle races.
> -	 * All current users do not store or use an atomic like update
> -	 */
> -	smp_mb__after_atomic();
> -	if (swait_active(&vcpu->wq)) {
> -		/*
> -		 * The vcpu gave up the cpu voluntarily, mark it as a good
> -		 * yield-candidate.
> -		 */
> +	if (kvm_vcpu_wake_up(vcpu))
>  		vcpu->ready = true;
> -		swake_up_one(&vcpu->wq);
> -		vcpu->stat.halt_wakeup++;
> -	}
>  	/*
>  	 * The VCPU might not be sleeping but is executing the VSIE. Let's
>  	 * kick it, so it leaves the SIE to process the request.
>