linux-kernel - Re: [PATCH] KVM: fix polling for guest halt continued even if disable it

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Date:	Tue, 15 Sep 2015 09:16:43 +0200
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	Wanpeng Li <wanpeng.li@...mail.com>,
	Paolo Bonzini <pbonzini@...hat.com>
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: fix polling for guest halt continued even if disable
 it

Am 14.09.2015 um 11:38 schrieb Wanpeng Li:
> If there is already some polling ongoing, it's impossible to disable the 
> polling, since as soon as somebody sets halt_poll_ns to 0, polling will 
> never stop, as grow and shrink are only handled if halt_poll_ns is != 0.
> 
> This patch fix it by reset vcpu->halt_poll_ns in order to stop polling 
> when polling is disabled.
> 
> Reported-by: Christian Borntraeger <borntraeger@...ibm.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
> ---
>  virt/kvm/kvm_main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4662a88..f756cac0 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2012,7 +2012,8 @@ out:
>  		else if (vcpu->halt_poll_ns < halt_poll_ns &&
>  			block_ns < halt_poll_ns)
>  			grow_halt_poll_ns(vcpu);
> -	}
> +	} else
> +		vcpu->halt_poll_ns = 0;
> 
>  	trace_kvm_vcpu_wakeup(block_ns, waited);
>  }
> 

Tested-by: Christian Borntraeger <borntraeger@...ibm.com>

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