KVM: PPC: Book3S HV: Counters for passthrough IRQ stats

Add VCPU stat counters to track affinity for passthrough
interrupts.

pthru_all: Counts all passthrough interrupts whose IRQ mappings are
           in the kvmppc_passthru_irq_map structure.
pthru_host: Counts all cached passthrough interrupts that were injected
	    from the host through kvm_set_irq (i.e. not handled in
	    real mode).
pthru_bad_aff: Counts how many cached passthrough interrupts have
               bad affinity (receiving CPU is not running VCPU that is
	       the target of the virtual interrupt in the guest).
Signed-off-by: Suresh Warrier <warrier@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/include/asm/kvm_host.h

@@ -137,6 +137,9 @@ struct kvm_vcpu_stat {
 	u64 ld_slow;
 	u64 st_slow;
 #endif
+	u64 pthru_all;
+	u64 pthru_host;
+	u64 pthru_bad_aff;
 };
 
 enum kvm_exit_types {

arch/powerpc/kvm/book3s.c

@@ -68,6 +68,9 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 	{ "ld_slow",     VCPU_STAT(ld_slow) },
 	{ "st",          VCPU_STAT(st) },
 	{ "st_slow",     VCPU_STAT(st_slow) },
+	{ "pthru_all",       VCPU_STAT(pthru_all) },
+	{ "pthru_host",      VCPU_STAT(pthru_host) },
+	{ "pthru_bad_aff",   VCPU_STAT(pthru_bad_aff) },
 	{ NULL }
 };
 

arch/powerpc/kvm/book3s_hv_rm_xics.c

@@ -716,11 +716,19 @@ int kvmppc_rm_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
 		icp->rm_eoied_irq = irq;
 	}
 
-	if (state->host_irq && state->intr_cpu != -1) {
-		int pcpu = cpu_first_thread_sibling(raw_smp_processor_id());
-		if (state->intr_cpu != pcpu)
-			xics_opal_rm_set_server(state->host_irq, pcpu);
-		state->intr_cpu = -1;
+	if (state->host_irq) {
+		++vcpu->stat.pthru_all;
+		if (state->intr_cpu != -1) {
+			int pcpu = raw_smp_processor_id();
+
+			pcpu = cpu_first_thread_sibling(pcpu);
+			++vcpu->stat.pthru_host;
+			if (state->intr_cpu != pcpu) {
+				++vcpu->stat.pthru_bad_aff;
+				xics_opal_rm_set_server(state->host_irq, pcpu);
+			}
+			state->intr_cpu = -1;
+		}
 	}
  bail:
 	return check_too_hard(xics, icp);