This is a note to let you know that I've just added the patch titled
KVM: PPC: Book3S HV P9: Restore stolen time logging in dtl
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-ppc-book3s-hv-p9-restore-stolen-time-logging-in-.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit afe3395a6c00b7cb77f86640479cda6046f95a6c
Author: Nicholas Piggin <npiggin@xxxxxxxxx>
Date: Thu Sep 8 23:25:44 2022 +1000
KVM: PPC: Book3S HV P9: Restore stolen time logging in dtl
[ Upstream commit 1a5486b3c3517aa1f608a10003ade4da122cb175 ]
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 <npiggin@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220908132545.4085849-4-npiggin@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 0f8dee657336..2feacb1ee9d9 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -249,6 +249,7 @@ 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
@@ -278,6 +279,12 @@ 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)
@@ -311,8 +318,14 @@ 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();
@@ -340,8 +353,21 @@ 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();
@@ -740,6 +766,18 @@ 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)
{
@@ -4534,7 +4572,6 @@ 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 */
@@ -4561,6 +4598,8 @@ 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)
@@ -4605,7 +4644,7 @@ 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);
@@ -4631,6 +4670,7 @@ 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;
context_tracking_guest_exit();
if (!vtime_accounting_enabled_this_cpu()) {
@@ -4708,6 +4748,7 @@ 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;
