KVM: Don't shrink/grow vCPU halt_poll_ns if host side polling is disabled

Don't waste cycles to shrink/grow vCPU halt_poll_ns if host
side polling is disabled.

Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fd68fbe..67ef3f2 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2360,20 +2360,23 @@ out:
        kvm_arch_vcpu_unblocking(vcpu);
        block_ns = ktime_to_ns(cur) - ktime_to_ns(start);
 
-       if (!vcpu_valid_wakeup(vcpu))
-               shrink_halt_poll_ns(vcpu);
-       else if (halt_poll_ns) {
-               if (block_ns <= vcpu->halt_poll_ns)
-                       ;
-               /* we had a long block, shrink polling */
-               else if (vcpu->halt_poll_ns && block_ns > halt_poll_ns)
+       if (!kvm_arch_no_poll(vcpu)) {
+               if (!vcpu_valid_wakeup(vcpu)) {
                        shrink_halt_poll_ns(vcpu);
-               /* we had a short halt and our poll time is too small */
-               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;
+               } else if (halt_poll_ns) {
+                       if (block_ns <= vcpu->halt_poll_ns)
+                               ;
+                       /* we had a long block, shrink polling */
+                       else if (vcpu->halt_poll_ns && block_ns > halt_poll_ns)
+                               shrink_halt_poll_ns(vcpu);
+                       /* we had a short halt and our poll time is too small */
+                       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, vcpu_valid_wakeup(vcpu));
        kvm_arch_vcpu_block_finish(vcpu);