[PATCH 7/8] powerpc/perf: add support for the hv 24x7 interface

[Cody P Schafer]

This provides a basic interface between hv_24x7 and perf. Similar to
the one provided for gpci, it lacks transaction support and does not
list any events.

Signed-off-by: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
---
 arch/powerpc/perf/hv-24x7.c | 354 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 354 insertions(+)
 create mode 100644 arch/powerpc/perf/hv-24x7.c

diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
new file mode 100644
index 0000000..fb49e66
--- /dev/null
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -0,0 +1,354 @@
+/*
+ * Hypervisor supplied "24x7" performance counter support
+ *
+ * Author: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
+ * 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-24x7: " fmt
+
+#include <linux/perf_event.h>
+#include <linux/module.h>
+#include <asm/firmware.h>
+#include <asm/hvcall.h>
+#include <asm/hv_24x7.h>
+#include <asm/hv_gpci.h>
+#include <asm/io.h>
+
+/* See arch/powerpc/include/asm/24x7.h for details on the hcall interface */
+
+/* TODO: Merging events:
+ * - Think of the hcall as an interface to a 4d array of counters:
+ *   - x = domains
+ *   - y = indexes in the domain (core, chip, vcpu, node, etc)
+ *   - z = offset into the counter space
+ *   - w = lpars (guest vms, "logical partitions")
+ * - A single request is: x,y,y_last,z,z_last,w,w_last
+ *   - this means we can retrieve a rectangle of counters in y,z for a single x.
+ *
+ * - Things to consider (ignoring w):
+ *   - input  cost_per_request = 16
+ *   - output cost_per_result(ys,zs)  = 8 + 8 * ys + ys * zs
+ *   - limited number of requests per hcall (must fit into 4K bytes)
+ *     - 4k = 16 [buffer header] - 16 [request size] * request_count
+ *     - 255 requests per hcall
+ *   - sometimes it will be more efficient to read extra data and discard
+ */
+
+PMU_RANGE_ATTR(domain, config, 0, 3); /* u3 0-6, one of HV_24X7_PERF_DOMAIN */
+PMU_RANGE_ATTR(starting_index, config, 16, 31); /* u16 */
+PMU_RANGE_ATTR(offset, config, 32, 63); /* u32, see "data_offset" */
+PMU_RANGE_ATTR(lpar, config1, 0, 15); /* u16 */
+
+PMU_RANGE_RESV(reserved1, config,   4, 15);
+PMU_RANGE_RESV(reserved2, config1, 16, 63);
+PMU_RANGE_RESV(reserved3, config2,  0, 63);
+
+static struct attribute *format_attr[] = {
+	&format_attr_domain.attr,
+	&format_attr_offset.attr,
+	&format_attr_starting_index.attr,
+	&format_attr_lpar.attr,
+	NULL,
+};
+
+static struct attribute_group format_group = {
+	.name = "format",
+	.attrs = format_attr,
+};
+
+static const struct attribute_group *attr_groups[] = {
+	&format_group,
+	NULL,
+};
+
+struct hv_perf_caps {
+	u16 version;
+	u16 other_allowed:1,
+	    ga:1,
+	    expanded:1,
+	    lab:1,
+	    unused:12;
+};
+
+static unsigned long hv_perf_caps_get(struct hv_perf_caps *caps)
+{
+	unsigned long r;
+	struct p {
+		struct hv_get_perf_counter_info_params params;
+		struct cv_system_performance_capabilities caps;
+	} __packed __aligned(sizeof(uint64_t));
+
+	struct p arg = {
+		.params = {
+			.counter_request = cpu_to_be32(
+					CIR_system_performance_capabilities),
+			.starting_index = cpu_to_be32(-1),
+			.counter_info_version_in = 0,
+		}
+	};
+
+	r = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
+			       virt_to_phys(&arg), sizeof(arg));
+	caps->version = arg.params.counter_info_version_out;
+	caps->other_allowed = arg.caps.perf_collect_privlidged;
+	caps->ga = (arg.caps.capability_mask & CV_CM_GA) >> CV_CM_GA;
+	caps->expanded = (arg.caps.capability_mask & CV_CM_EXPANDED)
+				>> CV_CM_EXPANDED;
+	caps->lab = (arg.caps.capability_mask & CV_CM_LAB) >> CV_CM_LAB;
+
+	return r;
+}
+
+static bool is_physical_domain(int domain)
+{
+	return  domain == HV_24X7_PERF_DOMAIN_PHYSICAL_CHIP ||
+		domain == HV_24X7_PERF_DOMAIN_PHYSICAL_CORE;
+}
+
+static unsigned long single_24x7_request(u8 domain, u32 offset, u16 ix,
+					 u16 lpar, u64 *res)
+{
+	unsigned long ret;
+	struct reqb {
+		struct hv_24x7_request_buffer buf;
+		struct hv_24x7_request req;
+	} request_buffer = {
+		.buf = {
+			.interface_version = HV_24X7_IF_VERSION_CURRENT,
+			.num_requests = 1,
+		},
+		.req = {
+			.performance_domain = domain,
+			.data_size = cpu_to_be16(8),
+			.data_offset = cpu_to_be32(offset),
+			.starting_lpar_ix = cpu_to_be16(lpar),
+			.max_num_lpars = cpu_to_be16(1),
+			.starting_ix = cpu_to_be16(ix),
+			.max_ix = cpu_to_be16(1),
+		}
+	};
+
+	struct resb {
+		struct hv_24x7_data_result_buffer buf;
+		struct hv_24x7_result res;
+		struct hv_24x7_result_element elem;
+		__be64 result;
+	} result_buffer = {};
+
+	ret = plpar_hcall_norets(H_GET_24X7_DATA,
+			virt_to_phys(&request_buffer), sizeof(request_buffer),
+			virt_to_phys(&result_buffer),  sizeof(result_buffer));
+
+	if (ret) {
+		/*
+		 * this failure is unexpected since we check if the exact same
+		 * hcall works in event_init
+		 */
+		pr_err_ratelimited("hcall failed: %d %#x %#x %d => 0x%lx (%ld) detail=0x%x failing ix=%x\n",
+				domain, offset, ix, lpar,
+				ret, ret,
+				result_buffer.buf.detailed_rc,
+				result_buffer.buf.failing_request_ix);
+		return ret;
+	}
+
+	*res = be64_to_cpu(result_buffer.result);
+	return ret;
+}
+
+static int h_24x7_event_init(struct perf_event *event)
+{
+	struct hv_perf_caps caps;
+	unsigned domain;
+	u64 ct;
+
+	/* Not our event */
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	/* Unused areas must be 0 */
+	if (event_get_reserved1(event) ||
+	    event_get_reserved2(event) ||
+	    event_get_reserved3(event)) {
+		pr_devel("reserved set when forbidden 0x%llx(0x%llx) 0x%llx(0x%llx) 0x%llx(0x%llx)\n",
+				event->attr.config,
+				event_get_reserved1(event),
+				event->attr.config1,
+				event_get_reserved2(event),
+				event->attr.config2,
+				event_get_reserved3(event));
+		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;
+
+	/* offset must be 8 byte aligned */
+	if (event_get_offset(event) % 8) {
+		pr_devel("bad alignment\n");
+		return -EINVAL;
+	}
+
+	/* Domains above 6 are invalid */
+	domain = event_get_domain(event);
+	if (domain > 6) {
+		pr_devel("invalid domain\n");
+		return -EINVAL;
+	}
+
+	if (hv_perf_caps_get(&caps)) {
+		pr_devel("could not get capabilities\n");
+		return -EIO;
+	}
+
+	/* PHYSICAL domains & other lpars require extra capabilities */
+	if (!caps.other_allowed && (is_physical_domain(domain) ||
+		(event_get_lpar(event) != event_get_lpar_max()))) {
+		pr_devel("hv permisions disallow\n");
+		return -EPERM;
+	}
+
+	/* see if the event complains */
+	if (single_24x7_request(event_get_domain(event),
+				event_get_offset(event),
+				event_get_starting_index(event),
+				event_get_lpar(event),
+				&ct)) {
+		pr_devel("test hcall failed\n");
+		return -EIO;
+	}
+
+	/*
+	 * 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;
+}
+
+static u64 h_24x7_get_value(struct perf_event *event)
+{
+	unsigned long ret;
+	u64 ct;
+	ret = single_24x7_request(event_get_domain(event),
+				  event_get_offset(event),
+				  event_get_starting_index(event),
+				  event_get_lpar(event),
+				  &ct);
+	if (ret)
+		/* We checked this in event init, shouldn't fail here... */
+		return 0;
+
+	return ct;
+}
+
+static void h_24x7_event_update(struct perf_event *event)
+{
+	s64 prev;
+	u64 now;
+	now = h_24x7_get_value(event);
+	prev = local64_xchg(&event->hw.prev_count, now);
+	local64_add(now - prev, &event->count);
+}
+
+static void h_24x7_event_start(struct perf_event *event, int flags)
+{
+	if (flags & PERF_EF_RELOAD)
+		local64_set(&event->hw.prev_count, h_24x7_get_value(event));
+	perf_swevent_start_hrtimer(event);
+}
+
+static void h_24x7_event_stop(struct perf_event *event, int flags)
+{
+	perf_swevent_cancel_hrtimer(event);
+	h_24x7_event_update(event);
+}
+
+static int h_24x7_event_add(struct perf_event *event, int flags)
+{
+	if (flags & PERF_EF_START)
+		h_24x7_event_start(event, flags);
+
+	return 0;
+}
+
+static void h_24x7_event_del(struct perf_event *event, int flags)
+{
+	h_24x7_event_stop(event, flags);
+}
+
+static void h_24x7_event_read(struct perf_event *event)
+{
+	h_24x7_event_update(event);
+}
+
+struct pmu h_24x7_pmu = {
+	.task_ctx_nr = perf_invalid_context,
+
+	.name = "hv_24x7",
+	.attr_groups = attr_groups,
+	.event_init  = h_24x7_event_init,
+	.add         = h_24x7_event_add,
+	.del         = h_24x7_event_del,
+	.start       = h_24x7_event_start,
+	.stop        = h_24x7_event_stop,
+	.read        = h_24x7_event_read,
+
+	.event_idx = perf_swevent_event_idx,
+};
+
+static int hv_24x7_init(void)
+{
+	int r;
+	unsigned long hret;
+	struct hv_perf_caps caps;
+
+	if (!firmware_has_feature(FW_FEATURE_LPAR)) {
+		pr_info("not an lpar, disabled\n");
+		return -ENODEV;
+	}
+
+	hret = hv_perf_caps_get(&caps);
+	if (hret) {
+		pr_info("could not obtain capabilities, error 0x%80lx, disabling\n",
+				hret);
+		return -ENODEV;
+	}
+
+	pr_info("gpci interface versions: hv:0x%x, kernel:0x%x\n",
+			caps.version, COUNTER_INFO_VERSION_CURRENT);
+
+	pr_info("gpci interface capabilities: other:%d ga:%d expanded:%d lab:%d\n",
+			caps.other_allowed, caps.ga,
+			caps.expanded,
+			caps.lab);
+
+	r = perf_pmu_register(&h_24x7_pmu, h_24x7_pmu.name, -1);
+	if (r)
+		return r;
+
+	return 0;
+}
+
+module_init(hv_24x7_init);
-- 
1.8.5.2

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