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Subject[PATCH v3 09/11] powerpc/perf: add support for the hv 24x7 interface
Date
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.

Example usage via perf tool:

perf stat -e 'hv_24x7/domain=2,offset=8,starting_index=0,lpar=0xffffffff/' -r 0 -C 0 -x ' ' sleep 0.1

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
---
arch/powerpc/perf/hv-24x7.c | 492 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 492 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..c1847a3
--- /dev/null
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -0,0 +1,492 @@
+/*
+ * Hypervisor supplied "24x7" 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-24x7: " fmt
+
+#include <linux/perf_event.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <asm/firmware.h>
+#include <asm/hvcall.h>
+#include <asm/io.h>
+
+#include "hv-24x7.h"
+#include "hv-24x7-catalog.h"
+#include "hv-common.h"
+
+/*
+ * 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_FORMAT_RANGE(domain, config, 0, 3); /* u3 0-6, one of HV_24X7_PERF_DOMAIN */
+PMU_FORMAT_RANGE(starting_index, config, 16, 31); /* u16 */
+PMU_FORMAT_RANGE(offset, config, 32, 63); /* u32, see "data_offset" */
+PMU_FORMAT_RANGE(lpar, config1, 0, 15); /* u16 */
+
+PMU_FORMAT_RANGE_RESERVED(reserved1, config, 4, 15);
+PMU_FORMAT_RANGE_RESERVED(reserved2, config1, 16, 63);
+PMU_FORMAT_RANGE_RESERVED(reserved3, config2, 0, 63);
+
+static struct attribute *format_attrs[] = {
+ &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_attrs,
+};
+
+/*
+ * read_offset_data - copy data from one buffer to another while treating the
+ * source buffer as a small view on the total avaliable
+ * source data.
+ *
+ * @dest: buffer to copy into
+ * @dest_len: length of @dest in bytes
+ * @requested_offset: the offset within the source data we want. Must be > 0
+ * @src: buffer to copy data from
+ * @src_len: length of @src in bytes
+ * @source_offset: the offset in the sorce data that (src,src_len) refers to.
+ * Must be > 0
+ *
+ * returns the number of bytes copied.
+ *
+ * The following ascii art shows the various buffer possitioning we need to
+ * handle, assigns some arbitrary varibles to points on the buffer, and then
+ * shows how we fiddle with those values to get things we care about (copy
+ * start in src and copy len)
+ *
+ * s = @src buffer
+ * d = @dest buffer
+ * '.' areas in d are written to.
+ *
+ * u
+ * x w v z
+ * d |.........|
+ * s |----------------------|
+ *
+ * u
+ * x w z v
+ * d |........------|
+ * s |------------------|
+ *
+ * x w u,z,v
+ * d |........|
+ * s |------------------|
+ *
+ * x,w u,v,z
+ * d |..................|
+ * s |------------------|
+ *
+ * x u
+ * w v z
+ * d |........|
+ * s |------------------|
+ *
+ * x z w v
+ * d |------|
+ * s |------|
+ *
+ * x = source_offset
+ * w = requested_offset
+ * z = source_offset + src_len
+ * v = requested_offset + dest_len
+ *
+ * w_offset_in_s = w - x = requested_offset - source_offset
+ * z_offset_in_s = z - x = src_len
+ * v_offset_in_s = v - x = request_offset + dest_len - src_len
+ */
+static ssize_t read_offset_data(void *dest, size_t dest_len,
+ loff_t requested_offset, void *src,
+ size_t src_len, loff_t source_offset)
+{
+ size_t w_offset_in_s = requested_offset - source_offset;
+ size_t z_offset_in_s = src_len;
+ size_t v_offset_in_s = requested_offset + dest_len - src_len;
+ size_t u_offset_in_s = min(z_offset_in_s, v_offset_in_s);
+ size_t copy_len = u_offset_in_s - w_offset_in_s;
+
+ if (requested_offset < 0 || source_offset < 0)
+ return -EINVAL;
+
+ if (z_offset_in_s <= w_offset_in_s)
+ return 0;
+
+ memcpy(dest, src + w_offset_in_s, copy_len);
+ return copy_len;
+}
+
+static unsigned long h_get_24x7_catalog_page(char page[static 4096],
+ u32 version, u32 index)
+{
+ WARN_ON(!IS_ALIGNED((unsigned long)page, 4096));
+ return plpar_hcall_norets(H_GET_24X7_CATALOG_PAGE,
+ virt_to_phys(page),
+ version,
+ index);
+}
+
+static ssize_t catalog_read(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf,
+ loff_t offset, size_t count)
+{
+ unsigned long hret;
+ ssize_t ret = 0;
+ size_t catalog_len = 0, catalog_page_len = 0, page_count = 0;
+ loff_t page_offset = 0;
+ uint32_t catalog_version_num = 0;
+ void *page = kmalloc(4096, GFP_USER);
+ struct hv_24x7_catalog_page_0 *page_0 = page;
+ if (!page)
+ return -ENOMEM;
+
+
+ hret = h_get_24x7_catalog_page(page, 0, 0);
+ if (hret) {
+ ret = -EIO;
+ goto e_free;
+ }
+
+ catalog_version_num = be32_to_cpu(page_0->version);
+ catalog_page_len = be32_to_cpu(page_0->length);
+ catalog_len = catalog_page_len * 4096;
+
+ page_offset = offset / 4096;
+ page_count = count / 4096;
+
+ if (page_offset >= catalog_page_len)
+ goto e_free;
+
+ if (page_offset != 0) {
+ hret = h_get_24x7_catalog_page(page, catalog_version_num,
+ page_offset);
+ if (hret) {
+ ret = -EIO;
+ goto e_free;
+ }
+ }
+
+ ret = read_offset_data(buf, count, offset,
+ page, 4096, page_offset * 4096);
+e_free:
+ if (hret)
+ pr_err("h_get_24x7_catalog_page(ver=%d, page=%lld) failed: rc=%ld\n",
+ catalog_version_num, page_offset, hret);
+ kfree(page);
+
+ pr_devel("catalog_read: offset=%lld(%lld) count=%zu(%zu) catalog_len=%zu(%zu) => %zd\n",
+ offset, page_offset, count, page_count, catalog_len,
+ catalog_page_len, ret);
+
+ return ret;
+}
+
+#define PAGE_0_ATTR(_name, _fmt, _expr) \
+static ssize_t _name##_show(struct device *dev, \
+ struct device_attribute *dev_attr, \
+ char *buf) \
+{ \
+ unsigned long hret; \
+ ssize_t ret = 0; \
+ void *page = kmalloc(4096, GFP_USER); \
+ struct hv_24x7_catalog_page_0 *page_0 = page; \
+ if (!page) \
+ return -ENOMEM; \
+ hret = h_get_24x7_catalog_page(page, 0, 0); \
+ if (hret) { \
+ ret = -EIO; \
+ goto e_free; \
+ } \
+ ret = sprintf(buf, _fmt, _expr); \
+e_free: \
+ kfree(page); \
+ return ret; \
+} \
+static DEVICE_ATTR_RO(_name)
+
+PAGE_0_ATTR(catalog_version, "%lld\n",
+ (unsigned long long)be32_to_cpu(page_0->version));
+PAGE_0_ATTR(catalog_len, "%lld\n",
+ (unsigned long long)be32_to_cpu(page_0->length) * 4096);
+static BIN_ATTR_RO(catalog, 0/* real length varies */);
+
+static struct bin_attribute *if_bin_attrs[] = {
+ &bin_attr_catalog,
+ NULL,
+};
+
+static struct attribute *if_attrs[] = {
+ &dev_attr_catalog_len.attr,
+ &dev_attr_catalog_version.attr,
+ NULL,
+};
+
+static struct attribute_group if_group = {
+ .name = "interface",
+ .bin_attrs = if_bin_attrs,
+ .attrs = if_attrs,
+};
+
+static const struct attribute_group *attr_groups[] = {
+ &format_group,
+ &if_group,
+ NULL,
+};
+
+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,
+ bool success_expected)
+{
+ unsigned long ret;
+
+ /*
+ * request_buffer and result_buffer are not required to be 4k aligned,
+ * but are not allowed to cross any 4k boundary. Aligning them to 4k is
+ * the simplest way to ensure that.
+ */
+ struct reqb {
+ struct hv_24x7_request_buffer buf;
+ struct hv_24x7_request req;
+ } __packed __aligned(4096) 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;
+ } __packed __aligned(4096) 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) {
+ if (success_expected)
+ 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 unsigned long event_24x7_request(struct perf_event *event, u64 *res,
+ bool success_expected)
+{
+ return single_24x7_request(event_get_domain(event),
+ event_get_offset(event),
+ event_get_starting_index(event),
+ event_get_lpar(event),
+ res,
+ success_expected);
+}
+
+static int h_24x7_event_init(struct perf_event *event)
+{
+ struct hv_perf_caps caps;
+ unsigned domain;
+ unsigned long hret;
+ 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 %d\n", domain);
+ return -EINVAL;
+ }
+
+ hret = hv_perf_caps_get(&caps);
+ if (hret) {
+ pr_devel("could not get capabilities: rc=%ld\n", hret);
+ return -EIO;
+ }
+
+ /* PHYSICAL domains & other lpars require extra capabilities */
+ if (!caps.collect_privileged && (is_physical_domain(domain) ||
+ (event_get_lpar(event) != event_get_lpar_max()))) {
+ pr_devel("hv permisions disallow: is_physical_domain:%d, lpar=0x%llx\n",
+ is_physical_domain(domain),
+ event_get_lpar(event));
+ return -EACCES;
+ }
+
+ /* see if the event complains */
+ if (event_24x7_request(event, &ct, false)) {
+ pr_devel("test hcall failed\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static u64 h_24x7_get_value(struct perf_event *event)
+{
+ unsigned long ret;
+ u64 ct;
+ ret = event_24x7_request(event, &ct, true);
+ 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));
+}
+
+static void h_24x7_event_stop(struct perf_event *event, int flags)
+{
+ 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 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_stop,
+ .start = h_24x7_event_start,
+ .stop = h_24x7_event_stop,
+ .read = h_24x7_event_update,
+
+ .event_idx = perf_event_nop_0,
+};
+
+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 a virtualized system, not enabling\n");
+ return -ENODEV;
+ }
+
+ hret = hv_perf_caps_get(&caps);
+ if (hret) {
+ pr_info("could not obtain capabilities, error 0x%80lx, not enabling\n",
+ hret);
+ return -ENODEV;
+ }
+
+ r = perf_pmu_register(&h_24x7_pmu, h_24x7_pmu.name, -1);
+ if (r)
+ return r;
+
+ return 0;
+}
+
+device_initcall(hv_24x7_init);
--
1.9.0


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