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authorPaul Mackerras <paulus@samba.org>2012-10-15 01:17:42 +0000
committerAlexander Graf <agraf@suse.de>2012-10-30 10:54:56 +0100
commit8455d79e2163997e479931b8d5b7e60a92cd2b86 (patch)
tree901616f2b871898e206181d082356fd0a54fe17c
parent2f12f03436847e063cda8cc4c339ad84961cbf39 (diff)
downloadlinux-8455d79e2163997e479931b8d5b7e60a92cd2b86.tar.bz2
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>
-rw-r--r--arch/powerpc/include/asm/kvm_host.h5
-rw-r--r--arch/powerpc/kvm/book3s_hv.c74
2 files changed, 40 insertions, 39 deletions
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 218534d46ae9..1e8cbd1299fc 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -563,9 +563,8 @@ struct kvm_vcpu_arch {
};
/* Values for vcpu->arch.state */
-#define KVMPPC_VCPU_STOPPED 0
-#define KVMPPC_VCPU_BUSY_IN_HOST 1
-#define KVMPPC_VCPU_RUNNABLE 2
+#define KVMPPC_VCPU_NOTREADY 0
+#define KVMPPC_VCPU_RUNNABLE 1
/* Values for vcpu->arch.io_gpr */
#define KVM_MMIO_REG_MASK 0x001f
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 89995fa6e945..61d293465e81 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -776,10 +776,7 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
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 @@ static void kvmppc_remove_runnable(struct kvmppc_vcore *vc,
{
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 void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
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 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
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 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
* 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 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
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);