Commit 1a5486b3 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

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: ecb6a720 ("KVM: PPC: Book3S HV P9: Remove most of the vcore logic")
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220908132545.4085849-4-npiggin@gmail.com
parent b31bc24a

arch/powerpc/kvm/book3s_hv.c

+45 −4
Original line number Diff line number Diff line
@@ -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;