From patchwork series 401307

https://patchwork.ozlabs.org//project/linuxppc-dev/list/?series=401307

arch/powerpc/include/asm/kvm_host.h

@@ -847,6 +847,11 @@ struct kvm_vcpu_arch {
 	gpa_t nested_io_gpr;
 	/* For nested APIv2 guests*/
 	struct kvmhv_nestedv2_io nestedv2_io;
+
+	/* Aggregate context switch and guest run time info (in ns) */
+	u64 l1_to_l2_cs_agg;
+	u64 l2_to_l1_cs_agg;
+	u64 l2_runtime_agg;
 #endif
 
 #ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING

arch/powerpc/include/asm/lppaca.h

@@ -62,7 +62,8 @@ struct lppaca {
 	u8	donate_dedicated_cpu;	/* Donate dedicated CPU cycles */
 	u8	fpregs_in_use;
 	u8	pmcregs_in_use;
-	u8	reserved8[28];
+	u8	l2_accumul_cntrs_enable;  /* Enable usage of counters for KVM guest */
+	u8	reserved8[27];
 	__be64	wait_state_cycles;	/* Wait cycles for this proc */
 	u8	reserved9[28];
 	__be16	slb_count;		/* # of SLBs to maintain */
@@ -92,9 +93,13 @@ struct lppaca {
 	/* cacheline 4-5 */
 
 	__be32	page_ins;		/* CMO Hint - # page ins by OS */
-	u8	reserved12[148];
+	u8	reserved12[28];
+	volatile __be64 l1_to_l2_cs_tb;
+	volatile __be64 l2_to_l1_cs_tb;
+	volatile __be64 l2_runtime_tb;
+	u8 reserved13[96];
 	volatile __be64 dtl_idx;	/* Dispatch Trace Log head index */
-	u8	reserved13[96];
+	u8	reserved14[96];
 } ____cacheline_aligned;
 
 #define lppaca_of(cpu)	(*paca_ptrs[cpu]->lppaca_ptr)

arch/powerpc/kvm/book3s_hv.c

@@ -4108,6 +4108,37 @@ static void vcpu_vpa_increment_dispatch(struct kvm_vcpu *vcpu)
 	}
 }
 
+static inline int kvmhv_get_l2_accumul(void)
+{
+	return get_lppaca()->l2_accumul_cntrs_enable;
+}
+
+static inline void kvmhv_set_l2_accumul(int val)
+{
+	get_lppaca()->l2_accumul_cntrs_enable = val;
+}
+
+static void do_trace_nested_cs_time(struct kvm_vcpu *vcpu)
+{
+	struct lppaca *lp = get_lppaca();
+	u64 l1_to_l2_ns, l2_to_l1_ns, l2_runtime_ns;
+
+	l1_to_l2_ns = tb_to_ns(be64_to_cpu(lp->l1_to_l2_cs_tb));
+	l2_to_l1_ns = tb_to_ns(be64_to_cpu(lp->l2_to_l1_cs_tb));
+	l2_runtime_ns = tb_to_ns(be64_to_cpu(lp->l2_runtime_tb));
+	trace_kvmppc_vcpu_exit_cs_time(vcpu, l1_to_l2_ns, l2_to_l1_ns,
+					l2_runtime_ns);
+	lp->l1_to_l2_cs_tb = 0;
+	lp->l2_to_l1_cs_tb = 0;
+	lp->l2_runtime_tb = 0;
+	kvmhv_set_l2_accumul(0);
+
+	// Maintain an aggregate of context switch times
+	vcpu->arch.l1_to_l2_cs_agg += l1_to_l2_ns;
+	vcpu->arch.l2_to_l1_cs_agg += l2_to_l1_ns;
+	vcpu->arch.l2_runtime_agg += l2_runtime_ns;
+}
+
 static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit,
 				     unsigned long lpcr, u64 *tb)
 {
@@ -4130,6 +4161,11 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit,
 	kvmppc_gse_put_u64(io->vcpu_run_input, KVMPPC_GSID_LPCR, lpcr);
 
 	accumulate_time(vcpu, &vcpu->arch.in_guest);
+
+	/* Enable the guest host context switch time tracking */
+	if (unlikely(trace_kvmppc_vcpu_exit_cs_time_enabled()))
+		kvmhv_set_l2_accumul(1);
+
 	rc = plpar_guest_run_vcpu(0, vcpu->kvm->arch.lpid, vcpu->vcpu_id,
 				  &trap, &i);
 
@@ -4156,6 +4192,10 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit,
 
 	timer_rearm_host_dec(*tb);
 
+	/* Record context switch and guest_run_time data */
+	if (kvmhv_get_l2_accumul())
+		do_trace_nested_cs_time(vcpu);
+
 	return trap;
 }
 

arch/powerpc/kvm/trace_hv.h

@@ -491,6 +491,31 @@ TRACE_EVENT(kvmppc_run_vcpu_enter,
 	TP_printk("VCPU %d: tgid=%d", __entry->vcpu_id, __entry->tgid)
 );
 
+TRACE_EVENT(kvmppc_vcpu_exit_cs_time,
+	TP_PROTO(struct kvm_vcpu *vcpu, u64 l1_to_l2_cs, u64 l2_to_l1_cs,
+		u64 l2_runtime),
+
+	TP_ARGS(vcpu, l1_to_l2_cs, l2_to_l1_cs, l2_runtime),
+
+	TP_STRUCT__entry(
+		__field(int,		vcpu_id)
+		__field(__u64,		l1_to_l2_cs_ns)
+		__field(__u64,		l2_to_l1_cs_ns)
+		__field(__u64,		l2_runtime_ns)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_id  = vcpu->vcpu_id;
+		__entry->l1_to_l2_cs_ns = l1_to_l2_cs;
+		__entry->l2_to_l1_cs_ns = l2_to_l1_cs;
+		__entry->l2_runtime_ns = l2_runtime;
+	),
+
+	TP_printk("VCPU %d: l1_to_l2_cs_time=%llu-ns l2_to_l1_cs_time=%llu-ns l2_runtime=%llu-ns",
+		__entry->vcpu_id,  __entry->l1_to_l2_cs_ns,
+		__entry->l2_to_l1_cs_ns, __entry->l2_runtime_ns)
+);
+
 TRACE_EVENT(kvmppc_run_vcpu_exit,
 	TP_PROTO(struct kvm_vcpu *vcpu),