@@ -2308,9 +2308,15 @@ static void shrink_halt_poll_ns(struct kvm_vcpu *vcpu)
old = val = vcpu->halt_poll_ns;
shrink = READ_ONCE(halt_poll_ns_shrink);
if (shrink == 0)
- val = 0;
- else
+ val = halt_poll_ns_grow_start;
+ else {
val /= shrink;
+ if (val < halt_poll_ns_grow_start)
+ val = halt_poll_ns_grow_start;
+ }
+
+ if (val > halt_poll_ns)
+ val = halt_poll_ns;
vcpu->halt_poll_ns = val;
trace_kvm_halt_poll_ns_shrink(vcpu->vcpu_id, val, old);
@@ -2385,21 +2391,12 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
block_ns = ktime_to_ns(cur) - ktime_to_ns(start);
if (!kvm_arch_no_poll(vcpu)) {
- if (!vcpu_valid_wakeup(vcpu)) {
+ /* we had a long block, shrink polling */
+ if (!vcpu_valid_wakeup(vcpu) || block_ns > halt_poll_ns)
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)
- 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;
- }
+ /* we had a short block and our poll time is too small */
+ else if (block_ns > vcpu->halt_poll_ns)
+ grow_halt_poll_ns(vcpu);
}
trace_kvm_vcpu_wakeup(block_ns, waited, vcpu_valid_wakeup(vcpu));
As user can adjust halt_poll_ns_grow_start and halt_poll_ns which leads to vcpu->halt_poll_ns beyond the two boundaries. This patch ensures vcpu->halt_poll_ns in that scope after growing or shrinking. If halt_poll_ns_shrink is 0, shrink vcpu->halt_poll_ns to halt_poll_ns_grow_start instead of 0. To disable poll we can set halt_poll_ns to 0. In case user wrongly set halt_poll_ns_grow_start > halt_poll_ns > 0, halt_poll_ns take precedency and poll time is a fixed value of halt_poll_ns. This patch also simplifies branch check based on the guest haltpoll code. Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> --- virt/kvm/kvm_main.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-)