powerpc/kvm-hv-pmu: Add perf-events for Hostwide counters

Update 'kvm-hv-pmu.c' to add five new perf-events mapped to the five
Hostwide counters. Since these newly introduced perf events are at system
wide scope and can be read from any L1-Lpar CPU, 'kvmppc_pmu' scope and
capabilities are updated appropriately.

Also introduce two new helpers. First is kvmppc_update_l0_stats() that uses
the infrastructure introduced in previous patches to issues the
H_GUEST_GET_STATE hcall L0-PowerVM to fetch guest-state-buffer holding the
latest values of these counters which is then parsed and 'l0_stats'
variable updated.

Second helper is kvmppc_pmu_event_update() which is called from
'kvmppv_pmu' callbacks and uses kvmppc_update_l0_stats() to update
'l0_stats' and the update the 'struct perf_event's event-counter.

Some minor updates to kvmppc_pmu_{add, del, read}() to remove some debug
scaffolding code.

Signed-off-by: Vaibhav Jain <[e-mail]>
Reviewed-by: Athira Rajeev <[e-mail]>
Signed-off-by: Madhavan Srinivasan <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

arch/powerpc/perf/kvm-hv-pmu.c

···
 #include "asm/guest-state-buffer.h"
 
 enum kvmppc_pmu_eventid {
+	KVMPPC_EVENT_HOST_HEAP,
+	KVMPPC_EVENT_HOST_HEAP_MAX,
+	KVMPPC_EVENT_HOST_PGTABLE,
+	KVMPPC_EVENT_HOST_PGTABLE_MAX,
+	KVMPPC_EVENT_HOST_PGTABLE_RECLAIM,
 	KVMPPC_EVENT_MAX,
 };
 
···
 /* GSB related structs needed to talk to L0 */
 static struct kvmppc_gs_msg *gsm_l0_stats;
 static struct kvmppc_gs_buff *gsb_l0_stats;
+static struct kvmppc_gs_parser gsp_l0_stats;
 
 static struct attribute *kvmppc_pmu_events_attr[] = {
+	KVMPPC_PMU_EVENT_ATTR(host_heap, KVMPPC_EVENT_HOST_HEAP),
+	KVMPPC_PMU_EVENT_ATTR(host_heap_max, KVMPPC_EVENT_HOST_HEAP_MAX),
+	KVMPPC_PMU_EVENT_ATTR(host_pagetable, KVMPPC_EVENT_HOST_PGTABLE),
+	KVMPPC_PMU_EVENT_ATTR(host_pagetable_max, KVMPPC_EVENT_HOST_PGTABLE_MAX),
+	KVMPPC_PMU_EVENT_ATTR(host_pagetable_reclaim, KVMPPC_EVENT_HOST_PGTABLE_RECLAIM),
 	NULL,
 };
 
···
 	.attrs = kvmppc_pmu_events_attr,
 };
 
-PMU_FORMAT_ATTR(event, "config:0");
+PMU_FORMAT_ATTR(event, "config:0-5");
 static struct attribute *kvmppc_pmu_format_attr[] = {
 	&format_attr_event.attr,
 	NULL,
···
 	&kvmppc_pmu_format_group,
 	NULL,
 };
+
+/*
+ * Issue the hcall to get the L0-host stats.
+ * Should be called with l0-stat lock held
+ */
+static int kvmppc_update_l0_stats(void)
+{
+	int rc;
+
+	/* With HOST_WIDE flags guestid and vcpuid will be ignored */
+	rc = kvmppc_gsb_recv(gsb_l0_stats, KVMPPC_GS_FLAGS_HOST_WIDE);
+	if (rc)
+		goto out;
+
+	/* Parse the guest state buffer is successful */
+	rc = kvmppc_gse_parse(&gsp_l0_stats, gsb_l0_stats);
+	if (rc)
+		goto out;
+
+	/* Update the l0 returned stats*/
+	memset(&l0_stats, 0, sizeof(l0_stats));
+	rc = kvmppc_gsm_refresh_info(gsm_l0_stats, gsb_l0_stats);
+
+out:
+	return rc;
+}
+
+/* Update the value of the given perf_event */
+static int kvmppc_pmu_event_update(struct perf_event *event)
+{
+	int rc;
+	u64 curr_val, prev_val;
+	unsigned long flags;
+	unsigned int config = event->attr.config;
+
+	/* Ensure no one else is modifying the l0_stats */
+	spin_lock_irqsave(&lock_l0_stats, flags);
+
+	rc = kvmppc_update_l0_stats();
+	if (!rc) {
+		switch (config) {
+		case KVMPPC_EVENT_HOST_HEAP:
+			curr_val = l0_stats.guest_heap;
+			break;
+		case KVMPPC_EVENT_HOST_HEAP_MAX:
+			curr_val = l0_stats.guest_heap_max;
+			break;
+		case KVMPPC_EVENT_HOST_PGTABLE:
+			curr_val = l0_stats.guest_pgtable_size;
+			break;
+		case KVMPPC_EVENT_HOST_PGTABLE_MAX:
+			curr_val = l0_stats.guest_pgtable_size_max;
+			break;
+		case KVMPPC_EVENT_HOST_PGTABLE_RECLAIM:
+			curr_val = l0_stats.guest_pgtable_reclaim;
+			break;
+		default:
+			rc = -ENOENT;
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(&lock_l0_stats, flags);
+
+	/* If no error than update the perf event */
+	if (!rc) {
+		prev_val = local64_xchg(&event->hw.prev_count, curr_val);
+		if (curr_val > prev_val)
+			local64_add(curr_val - prev_val, &event->count);
+	}
+
+	return rc;
+}
 
 static int kvmppc_pmu_event_init(struct perf_event *event)
 {
···
 
 static void kvmppc_pmu_del(struct perf_event *event, int flags)
 {
+	kvmppc_pmu_event_update(event);
 }
 
 static int kvmppc_pmu_add(struct perf_event *event, int flags)
 {
+	if (flags & PERF_EF_START)
+		return kvmppc_pmu_event_update(event);
 	return 0;
 }
 
 static void kvmppc_pmu_read(struct perf_event *event)
 {
+	kvmppc_pmu_event_update(event);
 }
 
 /* Return the size of the needed guest state buffer */
···
 	.read = kvmppc_pmu_read,
 	.attr_groups = kvmppc_pmu_attr_groups,
 	.type = -1,
+	.scope = PERF_PMU_SCOPE_SYS_WIDE,
+	.capabilities = PERF_PMU_CAP_NO_EXCLUDE | PERF_PMU_CAP_NO_INTERRUPT,
 };
 
 static int __init kvmppc_register_pmu(void)