powerpc/perf: Add support for the hv 24x7 interface

/*

 * 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

 */

/*

 * Example usage:

 *  perf stat -e 'hv_24x7/domain=2,offset=8,starting_index=0,lpar=0xffffffff/'

 */

/* u3 0-6, one of HV_24X7_PERF_DOMAIN */

EVENT_DEFINE_RANGE_FORMAT(domain, config, 0, 3);

/* u16 */

EVENT_DEFINE_RANGE_FORMAT(starting_index, config, 16, 31);

/* u32, see "data_offset" */

EVENT_DEFINE_RANGE_FORMAT(offset, config, 32, 63);

/* u16 */

EVENT_DEFINE_RANGE_FORMAT(lpar, config1, 0, 15);

EVENT_DEFINE_RANGE(reserved1, config,   4, 15);

EVENT_DEFINE_RANGE(reserved2, config1, 16, 63);

EVENT_DEFINE_RANGE(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,

};

static struct kmem_cache *hv_page_cache;

/*

 * 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 = kmem_cache_alloc(hv_page_cache, 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 = kmem_cache_alloc(hv_page_cache, 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 int h_24x7_event_idx(struct perf_event *event)

{

	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   = h_24x7_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 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;

	}

	hv_page_cache = kmem_cache_create("hv-page-4096", 4096, 4096, 0, NULL);

	if (!hv_page_cache)

		return -ENOMEM;

	r = perf_pmu_register(&h_24x7_pmu, h_24x7_pmu.name, -1);

	if (r)

		return r;

	return 0;

}

device_initcall(hv_24x7_init);