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

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Date:	Mon, 14 Sep 2015 17:38:51 +0800
From:	Wanpeng Li <wanpeng.li@...mail.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	Christian Borntraeger <borntraeger@...ibm.com>,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH] KVM: fix polling for guest halt continued even if disable it

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);
 }
-- 
1.9.1

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