diff options
| -rw-r--r-- | virt/kvm/kvm_main.c | 26 |
1 files changed, 16 insertions, 10 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index abc23e27173..a83ca63d26f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1694,6 +1694,7 @@ bool kvm_vcpu_yield_to(struct kvm_vcpu *target) { struct pid *pid; struct task_struct *task = NULL; + bool ret = false; rcu_read_lock(); pid = rcu_dereference(target->pid); @@ -1701,17 +1702,15 @@ bool kvm_vcpu_yield_to(struct kvm_vcpu *target) task = get_pid_task(target->pid, PIDTYPE_PID); rcu_read_unlock(); if (!task) - return false; + return ret; if (task->flags & PF_VCPU) { put_task_struct(task); - return false; - } - if (yield_to(task, 1)) { - put_task_struct(task); - return true; + return ret; } + ret = yield_to(task, 1); put_task_struct(task); - return false; + + return ret; } EXPORT_SYMBOL_GPL(kvm_vcpu_yield_to); @@ -1752,12 +1751,14 @@ bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu) return eligible; } #endif + void kvm_vcpu_on_spin(struct kvm_vcpu *me) { struct kvm *kvm = me->kvm; struct kvm_vcpu *vcpu; int last_boosted_vcpu = me->kvm->last_boosted_vcpu; int yielded = 0; + int try = 3; int pass; int i; @@ -1769,7 +1770,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) * VCPU is holding the lock that we need and will release it. * We approximate round-robin by starting at the last boosted VCPU. */ - for (pass = 0; pass < 2 && !yielded; pass++) { + for (pass = 0; pass < 2 && !yielded && try; pass++) { kvm_for_each_vcpu(i, vcpu, kvm) { if (!pass && i <= last_boosted_vcpu) { i = last_boosted_vcpu; @@ -1782,10 +1783,15 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) continue; if (!kvm_vcpu_eligible_for_directed_yield(vcpu)) continue; - if (kvm_vcpu_yield_to(vcpu)) { + + yielded = kvm_vcpu_yield_to(vcpu); + if (yielded > 0) { kvm->last_boosted_vcpu = i; - yielded = 1; break; + } else if (yielded < 0) { + try--; + if (!try) + break; } } } |