kvm: exit halt polling on need_resched() as well

single_task_running() is usually more general than need_resched()
but CFS_BANDWIDTH throttling will use resched_task() when there
is just one task to get the task to block. This was causing
long-need_resched warnings and was likely allowing VMs to
overrun their quota when halt polling.

Signed-off-by: Ben Segall <[email protected]>
Signed-off-by: Venkatesh Srinivas <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Cc: [email protected]
Reviewed-by: Jim Mattson <[email protected]>

virt/kvm/kvm_main.c

@@ -2973,7 +2973,8 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
 				goto out;
 			}
 			poll_end = cur = ktime_get();
-		} while (single_task_running() && ktime_before(cur, stop));
+		} while (single_task_running() && !need_resched() &&
+			 ktime_before(cur, stop));
 	}
 
 	prepare_to_rcuwait(&vcpu->wait);