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@de.ibm.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a25a731..eb4c9d2 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2043,7 +2043,8 @@ 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);
 }