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KVM: PPC: Book3S HV P9: Restore stolen time logging in dtl 

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: ecb6a7207f ("KVM: PPC: Book3S HV P9: Remove most of the vcore logic")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220908132545.4085849-4-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2022-09-08 23:25:44 +10:00 committed by Michael Ellerman
parent b31bc24a49
commit 1a5486b3c3
1 changed files with 45 additions and 4 deletions
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49
arch/powerpc/kvm/book3s_hv.c
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@ -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)
{
@ -4527,7 +4565,6 @@ 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 */
@ -4554,6 +4591,8 @@ 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)
@ -4598,7 +4637,7 @@ 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);
@ -4621,6 +4660,7 @@ 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;
if (!vtime_accounting_enabled_this_cpu()) {
powerpc_local_irq_pmu_restore(flags);
@ -4697,6 +4737,7 @@ 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;