[PATCH 6/8] powerpc/perf: add support for the hv gpci (get performance counter info) interface

[Cody P Schafer <cody@linux.vnet.ibm.com>]

This provides a basic link between perf and hv_gpci. Notably, it does
not yet support transactions and does not list any events (they can
still be manually composed).

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
---
 arch/powerpc/perf/hv-gpci.c | 235 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 235 insertions(+)
 create mode 100644 arch/powerpc/perf/hv-gpci.c

diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
new file mode 100644
index 0000000..31d9d59
--- /dev/null
+++ b/arch/powerpc/perf/hv-gpci.c
@@ -0,0 +1,235 @@
+/*
+ * Hypervisor supplied "gpci" ("get performance counter info") performance
+ * counter support
+ *
+ * Author: Cody P Schafer <cody@linux.vnet.ibm.com>
+ * Copyright 2014 IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#define pr_fmt(fmt) "hv-gpci: " fmt
+
+#include <linux/module.h>
+#include <linux/perf_event.h>
+#include <asm/firmware.h>
+#include <asm/hvcall.h>
+#include <asm/hv_gpci.h>
+#include <asm/io.h>
+
+/* See arch/powerpc/include/asm/hv_gpci.h for details on the hcall interface */
+
+PMU_RANGE_ATTR(request, config, 0, 31); /* u32 */
+PMU_RANGE_ATTR(starting_index, config, 32, 63); /* u32 */
+PMU_RANGE_ATTR(secondary_index, config1, 0, 15); /* u16 */
+PMU_RANGE_ATTR(counter_info_version, config1, 16, 23); /* u8 */
+PMU_RANGE_ATTR(length, config1, 24, 31); /* u8, bytes of data (1-8) */
+PMU_RANGE_ATTR(offset, config1, 32, 63); /* u32, byte offset */
+
+static struct attribute *format_attr[] = {
+	&format_attr_request.attr,
+	&format_attr_starting_index.attr,
+	&format_attr_secondary_index.attr,
+	&format_attr_counter_info_version.attr,
+
+	&format_attr_offset.attr,
+	&format_attr_length.attr,
+	NULL,
+};
+
+static struct attribute_group format_group = {
+	.name = "format",
+	.attrs = format_attr,
+};
+
+static const struct attribute_group *attr_groups[] = {
+	&format_group,
+	NULL,
+};
+
+static unsigned long single_gpci_request(u32 req, u32 starting_index,
+		u16 secondary_index, u8 version_in, u32 offset, u8 length,
+		u64 *value)
+{
+	unsigned long ret;
+	size_t i;
+	u64 count;
+
+	struct {
+		struct hv_get_perf_counter_info_params params;
+		union {
+			union h_gpci_cvs data;
+			uint8_t bytes[sizeof(union h_gpci_cvs)];
+		};
+	} arg = {
+		.params = {
+			.counter_request = cpu_to_be32(req),
+			.starting_index = cpu_to_be32(starting_index),
+			.secondary_index = cpu_to_be16(secondary_index),
+			.counter_info_version_in = version_in,
+		}
+	};
+
+	ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
+			virt_to_phys(&arg), sizeof(arg));
+	if (ret) {
+		pr_devel("hcall failed: 0x%lx\n", ret);
+		return ret;
+	}
+
+	/*
+	 * we verify offset and length are within the zeroed buffer at event
+	 * init.
+	 */
+	count = 0;
+	for (i = offset; i < offset + length; i++)
+		count |= arg.bytes[i] << (i - offset);
+
+	*value = count;
+	return ret;
+}
+
+static u64 h_gpci_get_value(struct perf_event *event)
+{
+	u64 count;
+	unsigned long ret = single_gpci_request(event_get_request(event),
+					event_get_starting_index(event),
+					event_get_secondary_index(event),
+					event_get_counter_info_version(event),
+					event_get_offset(event),
+					event_get_length(event),
+					&count);
+	if (ret)
+		return 0;
+	return count;
+}
+
+static void h_gpci_event_update(struct perf_event *event)
+{
+	s64 prev;
+	u64 now = h_gpci_get_value(event);
+	prev = local64_xchg(&event->hw.prev_count, now);
+	local64_add(now - prev, &event->count);
+}
+
+static void h_gpci_event_start(struct perf_event *event, int flags)
+{
+	local64_set(&event->hw.prev_count, h_gpci_get_value(event));
+	perf_swevent_start_hrtimer(event);
+}
+
+static void h_gpci_event_stop(struct perf_event *event, int flags)
+{
+	perf_swevent_cancel_hrtimer(event);
+	h_gpci_event_update(event);
+}
+
+static int h_gpci_event_add(struct perf_event *event, int flags)
+{
+	if (flags & PERF_EF_START)
+		h_gpci_event_start(event, flags);
+
+	return 0;
+}
+
+static void h_gpci_event_del(struct perf_event *event, int flags)
+{
+	h_gpci_event_stop(event, flags);
+}
+
+static void h_gpci_event_read(struct perf_event *event)
+{
+	h_gpci_event_update(event);
+}
+
+static int h_gpci_event_init(struct perf_event *event)
+{
+	u64 count;
+	u8 length;
+
+	/* Not our event */
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	/* config2 is unused */
+	if (event->attr.config2)
+		return -EINVAL;
+
+	/* unsupported modes and filters */
+	if (event->attr.exclude_user   ||
+	    event->attr.exclude_kernel ||
+	    event->attr.exclude_hv     ||
+	    event->attr.exclude_idle   ||
+	    event->attr.exclude_host   ||
+	    event->attr.exclude_guest  ||
+	    is_sampling_event(event)) /* no sampling */
+		return -EINVAL;
+
+	/* no branch sampling */
+	if (has_branch_stack(event))
+		return -EOPNOTSUPP;
+
+	length = event_get_length(event);
+	if (length < 1 || length > 8)
+		return -EINVAL;
+
+	/* last byte within the buffer? */
+	if ((event_get_offset(event) + length) > sizeof(union h_gpci_cvs))
+		return -EINVAL;
+
+	/* check if the request works... */
+	if (single_gpci_request(event_get_request(event),
+				event_get_starting_index(event),
+				event_get_secondary_index(event),
+				event_get_counter_info_version(event),
+				event_get_offset(event),
+				length,
+				&count))
+		return -EINVAL;
+
+	/*
+	 * Some of the events are per-cpu, some per-core, some per-chip, some
+	 * are global, and some access data from other virtual machines on the
+	 * same physical machine. We can't map the cpu value without a lot of
+	 * work. Instead, we pick an arbitrary cpu for all events on this pmu.
+	 */
+	event->cpu = 0;
+
+	perf_swevent_init_hrtimer(event);
+	return 0;
+}
+
+struct pmu h_gpci_pmu = {
+	.task_ctx_nr = perf_invalid_context,
+
+	.name = "hv_gpci",
+	.attr_groups = attr_groups,
+	.event_init = h_gpci_event_init,
+	.add = h_gpci_event_add,
+	.del = h_gpci_event_del,
+	.start = h_gpci_event_start,
+	.stop = h_gpci_event_stop,
+	.read = h_gpci_event_read,
+
+	.event_idx = perf_swevent_event_idx,
+};
+
+static int hv_gpci_init(void)
+{
+	int r;
+
+	if (!firmware_has_feature(FW_FEATURE_LPAR)) {
+		pr_info("Not running under phyp, not supported\n");
+		return -ENODEV;
+	}
+
+	r = perf_pmu_register(&h_gpci_pmu, h_gpci_pmu.name, -1);
+	if (r)
+		return r;
+
+	return 0;
+}
+
+module_init(hv_gpci_init);
-- 
1.8.5.2