Stolen time logging in dtl was removed from the P9 path, so guests had
no stolen time accounting. Add it back in a simpler way that still
avoids locks and per-core accounting code.
Fixes: ecb6a7207f92 ("KVM: PPC: Book3S HV P9: Remove most of the vcore logic")
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kvm/book3s_hv.c | 49 +++++++++++++++++++++++++++++++++---
1 file changed, 45 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 6fa518f6501d..0a0835edb64a 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -248,6 +248,7 @@ static void kvmppc_fast_vcpu_kick_hv(struct kvm_vcpu *vcpu)
/*
* We use the vcpu_load/put functions to measure stolen time.
+ *
* Stolen time is counted as time when either the vcpu is able to
* run as part of a virtual core, but the task running the vcore
* is preempted or sleeping, or when the vcpu needs something done
@@ -277,6 +278,12 @@ static void kvmppc_fast_vcpu_kick_hv(struct kvm_vcpu *vcpu)
* lock. The stolen times are measured in units of timebase ticks.
* (Note that the != TB_NIL checks below are purely defensive;
* they should never fail.)
+ *
+ * The POWER9 path is simpler, one vcpu per virtual core so the
+ * former case does not exist. If a vcpu is preempted when it is
+ * BUSY_IN_HOST and not ceded or otherwise blocked, then accumulate
+ * the stolen cycles in busy_stolen. RUNNING is not a preemptible
+ * state in the P9 path.
*/
static void kvmppc_core_start_stolen(struct kvmppc_vcore *vc, u64 tb)
@@ -310,8 +317,14 @@ static void kvmppc_core_vcpu_load_hv(struct kvm_vcpu
*vcpu, int cpu)
unsigned long flags;
u64 now;
- if (cpu_has_feature(CPU_FTR_ARCH_300))
+ if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+ if (vcpu->arch.busy_preempt != TB_NIL) {
+ WARN_ON_ONCE(vcpu->arch.state !=
KVMPPC_VCPU_BUSY_IN_HOST);
+ vc->stolen_tb += mftb() - vcpu->arch.busy_preempt;
+ vcpu->arch.busy_preempt = TB_NIL;
+ }
return;
+ }
now = mftb();
@@ -339,8 +352,21 @@ static void kvmppc_core_vcpu_put_hv(struct kvm_vcpu *vcpu)
unsigned long flags;
u64 now;
- if (cpu_has_feature(CPU_FTR_ARCH_300))
+ if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+ /*
+ * In the P9 path, RUNNABLE is not preemptible
+ * (nor takes host interrupts)
+ */
+ WARN_ON_ONCE(vcpu->arch.state == KVMPPC_VCPU_RUNNABLE);
+ /*
+ * Account stolen time when preempted while the vcpu task is
+ * running in the kernel (but not in qemu, which is INACTIVE).
+ */
+ if (task_is_running(current) &&
+ vcpu->arch.state == KVMPPC_VCPU_BUSY_IN_HOST)
+ vcpu->arch.busy_preempt = mftb();
return;
+ }
now = mftb();
@@ -739,6 +765,18 @@ static void __kvmppc_create_dtl_entry(struct kvm_vcpu
*vcpu,
vcpu->arch.dtl.dirty = true;
}
+static void kvmppc_create_dtl_entry_p9(struct kvm_vcpu *vcpu,
+ struct kvmppc_vcore *vc,
+ u64 now)
+{
+ unsigned long stolen;
+
+ stolen = vc->stolen_tb - vcpu->arch.stolen_logged;
+ vcpu->arch.stolen_logged = vc->stolen_tb;
+
+ __kvmppc_create_dtl_entry(vcpu, vc->pcpu, now, stolen);
+}
+
static void kvmppc_create_dtl_entry(struct kvm_vcpu *vcpu,
struct kvmppc_vcore *vc)
{
@@ -4470,7 +4508,6 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64
time_limit,
vc = vcpu->arch.vcore;
vcpu->arch.ceded = 0;
vcpu->arch.run_task = current;
- vcpu->arch.state = KVMPPC_VCPU_RUNNABLE;
vcpu->arch.last_inst = KVM_INST_FETCH_FAILED;
/* See if the MMU is ready to go */
@@ -4497,6 +4534,8 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64
time_limit,
/* flags save not required, but irq_pmu has no disable/enable API */
powerpc_local_irq_pmu_save(flags);
+ vcpu->arch.state = KVMPPC_VCPU_RUNNABLE;
+
if (signal_pending(current))
goto sigpend;
if (need_resched() || !kvm->arch.mmu_ready)
@@ -4536,7 +4575,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64
time_limit,
tb = mftb();
- __kvmppc_create_dtl_entry(vcpu, pcpu, tb + vc->tb_offset, 0);
+ kvmppc_create_dtl_entry_p9(vcpu, vc, tb + vc->tb_offset);
trace_kvm_guest_enter(vcpu);
@@ -4577,6 +4616,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64
time_limit,
vcpu->cpu = -1;
vcpu->arch.thread_cpu = -1;
+ vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
powerpc_local_irq_pmu_restore(flags);
@@ -4639,6 +4679,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64
time_limit,
out:
vcpu->cpu = -1;
vcpu->arch.thread_cpu = -1;
+ vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
powerpc_local_irq_pmu_restore(flags);
preempt_enable();
goto done;
--
2.35.1
