[PATCH 1/3] powerpc/kvm: simplify the entering logic for secondary thread
Liu Ping Fan
kernelfans at gmail.com
Tue Nov 5 18:42:42 EST 2013
After the primary vcpu changes vcore_state to VCORE_RUNNING, there is
very little chance to schedule to secondary vcpu. So if we change the
code sequence around set vcore_state to VCORE_RUNNING and disable
preemption, we lost little. But we simplify the entering logi, based on
the fact that if primary vcpu runs, the secondary vcpu can not be scheduled.
Signed-off-by: Liu Ping Fan <pingfank at linux.vnet.ibm.com>
---
arch/powerpc/kvm/book3s_hv.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 62a2b5a..38b1fc0 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1222,8 +1222,8 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
kvmppc_create_dtl_entry(vcpu, vc);
}
- vc->vcore_state = VCORE_RUNNING;
preempt_disable();
+ vc->vcore_state = VCORE_RUNNING;
spin_unlock(&vc->lock);
kvm_guest_enter();
@@ -1351,12 +1351,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
* this thread straight away and have it join in.
*/
if (!signal_pending(current)) {
- if (vc->vcore_state == VCORE_RUNNING &&
- VCORE_EXIT_COUNT(vc) == 0) {
- vcpu->arch.ptid = vc->n_runnable - 1;
- kvmppc_create_dtl_entry(vcpu, vc);
- kvmppc_start_thread(vcpu);
- } else if (vc->vcore_state == VCORE_SLEEPING) {
+ if (vc->vcore_state == VCORE_SLEEPING) {
wake_up(&vc->wq);
}
--
1.8.1.4
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