KVM: PPC: Book3S HV: Run virtual core whenever any vcpus in it can run
Currently the Book3S HV code implements a policy on multi-threaded
processors (i.e. POWER7) that requires all of the active vcpus in a
virtual core to be ready to run before we run the virtual core.
However, that causes problems on reset, because reset stops all vcpus
except vcpu 0, and can also reduce throughput since all four threads
in a virtual core have to wait whenever any one of them hits a
hypervisor page fault.
This relaxes the policy, allowing the virtual core to run as soon as
any vcpu in it is runnable. With this, the KVMPPC_VCPU_STOPPED state
and the KVMPPC_VCPU_BUSY_IN_HOST state have been combined into a single
KVMPPC_VCPU_NOTREADY state, since we no longer need to distinguish
between them.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 89995fa..61d2934 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -776,10 +776,7 @@
kvmppc_mmu_book3s_hv_init(vcpu);
- /*
- * We consider the vcpu stopped until we see the first run ioctl for it.
- */
- vcpu->arch.state = KVMPPC_VCPU_STOPPED;
+ vcpu->arch.state = KVMPPC_VCPU_NOTREADY;
init_waitqueue_head(&vcpu->arch.cpu_run);
@@ -866,9 +863,8 @@
{
if (vcpu->arch.state != KVMPPC_VCPU_RUNNABLE)
return;
- vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
+ vcpu->arch.state = KVMPPC_VCPU_NOTREADY;
--vc->n_runnable;
- ++vc->n_busy;
list_del(&vcpu->arch.run_list);
}
@@ -1169,7 +1165,6 @@
static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
{
int n_ceded;
- int prev_state;
struct kvmppc_vcore *vc;
struct kvm_vcpu *v, *vn;
@@ -1186,7 +1181,6 @@
vcpu->arch.ceded = 0;
vcpu->arch.run_task = current;
vcpu->arch.kvm_run = kvm_run;
- prev_state = vcpu->arch.state;
vcpu->arch.state = KVMPPC_VCPU_RUNNABLE;
list_add_tail(&vcpu->arch.run_list, &vc->runnable_threads);
++vc->n_runnable;
@@ -1196,35 +1190,26 @@
* If the vcore is already running, we may be able to start
* this thread straight away and have it join in.
*/
- if (prev_state == KVMPPC_VCPU_STOPPED) {
+ 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) {
+ wake_up(&vc->wq);
}
- } else if (prev_state == KVMPPC_VCPU_BUSY_IN_HOST)
- --vc->n_busy;
+ }
while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE &&
!signal_pending(current)) {
- if (vc->n_busy || vc->vcore_state != VCORE_INACTIVE) {
+ if (vc->vcore_state != VCORE_INACTIVE) {
spin_unlock(&vc->lock);
kvmppc_wait_for_exec(vcpu, TASK_INTERRUPTIBLE);
spin_lock(&vc->lock);
continue;
}
- vc->runner = vcpu;
- n_ceded = 0;
- list_for_each_entry(v, &vc->runnable_threads, arch.run_list)
- if (!v->arch.pending_exceptions)
- n_ceded += v->arch.ceded;
- if (n_ceded == vc->n_runnable)
- kvmppc_vcore_blocked(vc);
- else
- kvmppc_run_core(vc);
-
list_for_each_entry_safe(v, vn, &vc->runnable_threads,
arch.run_list) {
kvmppc_core_prepare_to_enter(v);
@@ -1236,23 +1221,40 @@
wake_up(&v->arch.cpu_run);
}
}
+ if (!vc->n_runnable || vcpu->arch.state != KVMPPC_VCPU_RUNNABLE)
+ break;
+ vc->runner = vcpu;
+ n_ceded = 0;
+ list_for_each_entry(v, &vc->runnable_threads, arch.run_list)
+ if (!v->arch.pending_exceptions)
+ n_ceded += v->arch.ceded;
+ if (n_ceded == vc->n_runnable)
+ kvmppc_vcore_blocked(vc);
+ else
+ kvmppc_run_core(vc);
vc->runner = NULL;
}
- if (signal_pending(current)) {
- while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE &&
- (vc->vcore_state == VCORE_RUNNING ||
- vc->vcore_state == VCORE_EXITING)) {
- spin_unlock(&vc->lock);
- kvmppc_wait_for_exec(vcpu, TASK_UNINTERRUPTIBLE);
- spin_lock(&vc->lock);
- }
- if (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE) {
- kvmppc_remove_runnable(vc, vcpu);
- vcpu->stat.signal_exits++;
- kvm_run->exit_reason = KVM_EXIT_INTR;
- vcpu->arch.ret = -EINTR;
- }
+ while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE &&
+ (vc->vcore_state == VCORE_RUNNING ||
+ vc->vcore_state == VCORE_EXITING)) {
+ spin_unlock(&vc->lock);
+ kvmppc_wait_for_exec(vcpu, TASK_UNINTERRUPTIBLE);
+ spin_lock(&vc->lock);
+ }
+
+ if (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE) {
+ kvmppc_remove_runnable(vc, vcpu);
+ vcpu->stat.signal_exits++;
+ kvm_run->exit_reason = KVM_EXIT_INTR;
+ vcpu->arch.ret = -EINTR;
+ }
+
+ if (vc->n_runnable && vc->vcore_state == VCORE_INACTIVE) {
+ /* Wake up some vcpu to run the core */
+ v = list_first_entry(&vc->runnable_threads,
+ struct kvm_vcpu, arch.run_list);
+ wake_up(&v->arch.cpu_run);
}
spin_unlock(&vc->lock);