// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Hypervisor supplied "gpci" ("get performance counter info") performance
 * counter support
 *
 * Author: Cody P Schafer <cody@linux.vnet.ibm.com>
 * Copyright 2014 IBM Corporation.
 */

#define pr_fmt(fmt) "hv-gpci: " fmt

#include <linux/init.h>
#include <linux/perf_event.h>
#include <asm/firmware.h>
#include <asm/hvcall.h>
#include <asm/io.h>

#include "hv-gpci.h"
#include "hv-common.h"

/*
 * Example usage:
 *  perf stat -e 'hv_gpci/counter_info_version=3,offset=0,length=8,
 *                secondary_index=0,starting_index=0xffffffff,request=0x10/' ...
 */

/* u32 */
EVENT_DEFINE_RANGE_FORMAT(request, config, 0, 31);
/* u32 */
/*
 * Note that starting_index, phys_processor_idx, sibling_part_id,
 * hw_chip_id, partition_id all refer to the same bit range. They
 * are basically aliases for the starting_index. The specific alias
 * used depends on the event. See REQUEST_IDX_KIND in hv-gpci-requests.h
 */
EVENT_DEFINE_RANGE_FORMAT(starting_index, config, 32, 63);
EVENT_DEFINE_RANGE_FORMAT_LITE(phys_processor_idx, config, 32, 63);
EVENT_DEFINE_RANGE_FORMAT_LITE(sibling_part_id, config, 32, 63);
EVENT_DEFINE_RANGE_FORMAT_LITE(hw_chip_id, config, 32, 63);
EVENT_DEFINE_RANGE_FORMAT_LITE(partition_id, config, 32, 63);

/* u16 */
EVENT_DEFINE_RANGE_FORMAT(secondary_index, config1, 0, 15);
/* u8 */
EVENT_DEFINE_RANGE_FORMAT(counter_info_version, config1, 16, 23);
/* u8, bytes of data (1-8) */
EVENT_DEFINE_RANGE_FORMAT(length, config1, 24, 31);
/* u32, byte offset */
EVENT_DEFINE_RANGE_FORMAT(offset, config1, 32, 63);

static cpumask_t hv_gpci_cpumask;

static struct attribute *format_attrs[] = {
        &format_attr_request.attr,
        &format_attr_starting_index.attr,
        &format_attr_phys_processor_idx.attr,
        &format_attr_sibling_part_id.attr,
        &format_attr_hw_chip_id.attr,
        &format_attr_partition_id.attr,
        &format_attr_secondary_index.attr,
        &format_attr_counter_info_version.attr,

        &format_attr_offset.attr,
        &format_attr_length.attr,
        NULL,
};

static const struct attribute_group format_group = {
        .name = "format",
        .attrs = format_attrs,
};

static struct attribute_group event_group = {
        .name  = "events",
        /* .attrs is set in init */
};

#define HV_CAPS_ATTR(_name, _format)                            \
static ssize_t _name##_show(struct device *dev,                 \
                            struct device_attribute *attr,      \
                            char *page)                         \
{                                                               \
        struct hv_perf_caps caps;                               \
        unsigned long hret = hv_perf_caps_get(&caps);           \
        if (hret)                                               \
                return -EIO;                                    \
                                                                \
        return sprintf(page, _format, caps._name);              \
}                                                               \
static struct device_attribute hv_caps_attr_##_name = __ATTR_RO(_name)

static ssize_t kernel_version_show(struct device *dev,
                                   struct device_attribute *attr,
                                   char *page)
{
        return sprintf(page, "0x%x\n", COUNTER_INFO_VERSION_CURRENT);
}

static ssize_t cpumask_show(struct device *dev,
                            struct device_attribute *attr, char *buf)
{
        return cpumap_print_to_pagebuf(true, buf, &hv_gpci_cpumask);
}

/* Interface attribute array index to store system information */
#define INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR   6
#define INTERFACE_PROCESSOR_CONFIG_ATTR         7
#define INTERFACE_AFFINITY_DOMAIN_VIA_VP_ATTR   8
#define INTERFACE_AFFINITY_DOMAIN_VIA_DOM_ATTR  9
#define INTERFACE_AFFINITY_DOMAIN_VIA_PAR_ATTR  10
#define INTERFACE_NULL_ATTR                     11

/* Counter request value to retrieve system information */
enum {
        PROCESSOR_BUS_TOPOLOGY,
        PROCESSOR_CONFIG,
        AFFINITY_DOMAIN_VIA_VP, /* affinity domain via virtual processor */
        AFFINITY_DOMAIN_VIA_DOM, /* affinity domain via domain */
        AFFINITY_DOMAIN_VIA_PAR, /* affinity domain via partition */
};

static int sysinfo_counter_request[] = {
        [PROCESSOR_BUS_TOPOLOGY] = 0xD0,
        [PROCESSOR_CONFIG] = 0x90,
        [AFFINITY_DOMAIN_VIA_VP] = 0xA0,
        [AFFINITY_DOMAIN_VIA_DOM] = 0xB0,
        [AFFINITY_DOMAIN_VIA_PAR] = 0xB1,
};

static DEFINE_PER_CPU(char, hv_gpci_reqb[HGPCI_REQ_BUFFER_SIZE]) __aligned(sizeof(uint64_t));

static unsigned long systeminfo_gpci_request(u32 req, u32 starting_index,
                        u16 secondary_index, char *buf,
                        size_t *n, struct hv_gpci_request_buffer *arg)
{
        unsigned long ret;
        size_t i, j;

        arg->params.counter_request = cpu_to_be32(req);
        arg->params.starting_index = cpu_to_be32(starting_index);
        arg->params.secondary_index = cpu_to_be16(secondary_index);

        ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
                        virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);

        /*
         * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL',
         * which means that the current buffer size cannot accommodate
         * all the information and a partial buffer returned.
         * hcall fails incase of ret value other than H_SUCCESS or H_PARAMETER.
         *
         * ret value as H_AUTHORITY implies that partition is not permitted to retrieve
         * performance information, and required to set
         * "Enable Performance Information Collection" option.
         */
        if (ret == H_AUTHORITY)
                return -EPERM;

        /*
         * hcall can fail with other possible ret value like H_PRIVILEGE/H_HARDWARE
         * because of invalid buffer-length/address or due to some hardware
         * error.
         */
        if (ret && (ret != H_PARAMETER))
                return -EIO;

        /*
         * hcall H_GET_PERF_COUNTER_INFO populates the 'returned_values'
         * to show the total number of counter_value array elements
         * returned via hcall.
         * hcall also populates 'cv_element_size' corresponds to individual
         * counter_value array element size. Below loop go through all
         * counter_value array elements as per their size and add it to
         * the output buffer.
         */
        for (i = 0; i < be16_to_cpu(arg->params.returned_values); i++) {
                j = i * be16_to_cpu(arg->params.cv_element_size);

                for (; j < (i + 1) * be16_to_cpu(arg->params.cv_element_size); j++)
                        *n += sprintf(buf + *n,  "%02x", (u8)arg->bytes[j]);
                *n += sprintf(buf + *n,  "\n");
        }

        if (*n >= PAGE_SIZE) {
                pr_info("System information exceeds PAGE_SIZE\n");
                return -EFBIG;
        }

        return ret;
}

static ssize_t processor_bus_topology_show(struct device *dev, struct device_attribute *attr,
                                char *buf)
{
        struct hv_gpci_request_buffer *arg;
        unsigned long ret;
        size_t n = 0;

        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

        /*
         * Pass the counter request value 0xD0 corresponds to request
         * type 'Processor_bus_topology', to retrieve
         * the system topology information.
         * starting_index value implies the starting hardware
         * chip id.
         */
        ret = systeminfo_gpci_request(sysinfo_counter_request[PROCESSOR_BUS_TOPOLOGY],
                        0, 0, buf, &n, arg);

        if (!ret)
                return n;

        if (ret != H_PARAMETER)
                goto out;

        /*
         * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', which
         * implies that buffer can't accommodate all information, and a partial buffer
         * returned. To handle that, we need to make subsequent requests
         * with next starting index to retrieve additional (missing) data.
         * Below loop do subsequent hcalls with next starting index and add it
         * to buffer util we get all the information.
         */
        while (ret == H_PARAMETER) {
                int returned_values = be16_to_cpu(arg->params.returned_values);
                int elementsize = be16_to_cpu(arg->params.cv_element_size);
                int last_element = (returned_values - 1) * elementsize;

                /*
                 * Since the starting index value is part of counter_value
                 * buffer elements, use the starting index value in the last
                 * element and add 1 to make subsequent hcalls.
                 */
                u32 starting_index = arg->bytes[last_element + 3] +
                                (arg->bytes[last_element + 2] << 8) +
                                (arg->bytes[last_element + 1] << 16) +
                                (arg->bytes[last_element] << 24) + 1;

                memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

                ret = systeminfo_gpci_request(sysinfo_counter_request[PROCESSOR_BUS_TOPOLOGY],
                                starting_index, 0, buf, &n, arg);

                if (!ret)
                        return n;

                if (ret != H_PARAMETER)
                        goto out;
        }

        return n;

out:
        put_cpu_var(hv_gpci_reqb);
        return ret;
}

static ssize_t processor_config_show(struct device *dev, struct device_attribute *attr,
                                        char *buf)
{
        struct hv_gpci_request_buffer *arg;
        unsigned long ret;
        size_t n = 0;

        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

        /*
         * Pass the counter request value 0x90 corresponds to request
         * type 'Processor_config', to retrieve
         * the system processor information.
         * starting_index value implies the starting hardware
         * processor index.
         */
        ret = systeminfo_gpci_request(sysinfo_counter_request[PROCESSOR_CONFIG],
                        0, 0, buf, &n, arg);

        if (!ret)
                return n;

        if (ret != H_PARAMETER)
                goto out;

        /*
         * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', which
         * implies that buffer can't accommodate all information, and a partial buffer
         * returned. To handle that, we need to take subsequent requests
         * with next starting index to retrieve additional (missing) data.
         * Below loop do subsequent hcalls with next starting index and add it
         * to buffer util we get all the information.
         */
        while (ret == H_PARAMETER) {
                int returned_values = be16_to_cpu(arg->params.returned_values);
                int elementsize = be16_to_cpu(arg->params.cv_element_size);
                int last_element = (returned_values - 1) * elementsize;

                /*
                 * Since the starting index is part of counter_value
                 * buffer elements, use the starting index value in the last
                 * element and add 1 to subsequent hcalls.
                 */
                u32 starting_index = arg->bytes[last_element + 3] +
                                (arg->bytes[last_element + 2] << 8) +
                                (arg->bytes[last_element + 1] << 16) +
                                (arg->bytes[last_element] << 24) + 1;

                memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

                ret = systeminfo_gpci_request(sysinfo_counter_request[PROCESSOR_CONFIG],
                                starting_index, 0, buf, &n, arg);

                if (!ret)
                        return n;

                if (ret != H_PARAMETER)
                        goto out;
        }

        return n;

out:
        put_cpu_var(hv_gpci_reqb);
        return ret;
}

static ssize_t affinity_domain_via_virtual_processor_show(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        struct hv_gpci_request_buffer *arg;
        unsigned long ret;
        size_t n = 0;

        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

        /*
         * Pass the counter request 0xA0 corresponds to request
         * type 'Affinity_domain_information_by_virutal_processor',
         * to retrieve the system affinity domain information.
         * starting_index value refers to the starting hardware
         * processor index.
         */
        ret = systeminfo_gpci_request(sysinfo_counter_request[AFFINITY_DOMAIN_VIA_VP],
                        0, 0, buf, &n, arg);

        if (!ret)
                return n;

        if (ret != H_PARAMETER)
                goto out;

        /*
         * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', which
         * implies that buffer can't accommodate all information, and a partial buffer
         * returned. To handle that, we need to take subsequent requests
         * with next secondary index to retrieve additional (missing) data.
         * Below loop do subsequent hcalls with next secondary index and add it
         * to buffer util we get all the information.
         */
        while (ret == H_PARAMETER) {
                int returned_values = be16_to_cpu(arg->params.returned_values);
                int elementsize = be16_to_cpu(arg->params.cv_element_size);
                int last_element = (returned_values - 1) * elementsize;

                /*
                 * Since the starting index and secondary index type is part of the
                 * counter_value buffer elements, use the starting index value in the
                 * last array element as subsequent starting index, and use secondary index
                 * value in the last array element plus 1 as subsequent secondary index.
                 * For counter request '0xA0', starting index points to partition id
                 * and secondary index points to corresponding virtual processor index.
                 */
                u32 starting_index = arg->bytes[last_element + 1] + (arg->bytes[last_element] << 8);
                u16 secondary_index = arg->bytes[last_element + 3] +
                                (arg->bytes[last_element + 2] << 8) + 1;

                memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

                ret = systeminfo_gpci_request(sysinfo_counter_request[AFFINITY_DOMAIN_VIA_VP],
                                starting_index, secondary_index, buf, &n, arg);

                if (!ret)
                        return n;

                if (ret != H_PARAMETER)
                        goto out;
        }

        return n;

out:
        put_cpu_var(hv_gpci_reqb);
        return ret;
}

static ssize_t affinity_domain_via_domain_show(struct device *dev, struct device_attribute *attr,
                                                char *buf)
{
        struct hv_gpci_request_buffer *arg;
        unsigned long ret;
        size_t n = 0;

        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

        /*
         * Pass the counter request 0xB0 corresponds to request
         * type 'Affinity_domain_information_by_domain',
         * to retrieve the system affinity domain information.
         * starting_index value refers to the starting hardware
         * processor index.
         */
        ret = systeminfo_gpci_request(sysinfo_counter_request[AFFINITY_DOMAIN_VIA_DOM],
                        0, 0, buf, &n, arg);

        if (!ret)
                return n;

        if (ret != H_PARAMETER)
                goto out;

        /*
         * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', which
         * implies that buffer can't accommodate all information, and a partial buffer
         * returned. To handle that, we need to take subsequent requests
         * with next starting index to retrieve additional (missing) data.
         * Below loop do subsequent hcalls with next starting index and add it
         * to buffer util we get all the information.
         */
        while (ret == H_PARAMETER) {
                int returned_values = be16_to_cpu(arg->params.returned_values);
                int elementsize = be16_to_cpu(arg->params.cv_element_size);
                int last_element = (returned_values - 1) * elementsize;

                /*
                 * Since the starting index value is part of counter_value
                 * buffer elements, use the starting index value in the last
                 * element and add 1 to make subsequent hcalls.
                 */
                u32 starting_index = arg->bytes[last_element + 1] +
                        (arg->bytes[last_element] << 8) + 1;

                memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

                ret = systeminfo_gpci_request(sysinfo_counter_request[AFFINITY_DOMAIN_VIA_DOM],
                                        starting_index, 0, buf, &n, arg);

                if (!ret)
                        return n;

                if (ret != H_PARAMETER)
                        goto out;
        }

        return n;

out:
        put_cpu_var(hv_gpci_reqb);
        return ret;
}

static void affinity_domain_via_partition_result_parse(int returned_values,
                        int element_size, char *buf, size_t *last_element,
                        size_t *n, struct hv_gpci_request_buffer *arg)
{
        size_t i = 0, j = 0;
        size_t k, l, m;
        uint16_t total_affinity_domain_ele, size_of_each_affinity_domain_ele;

        /*
         * hcall H_GET_PERF_COUNTER_INFO populates the 'returned_values'
         * to show the total number of counter_value array elements
         * returned via hcall.
         * Unlike other request types, the data structure returned by this
         * request is variable-size. For this counter request type,
         * hcall populates 'cv_element_size' corresponds to minimum size of
         * the structure returned i.e; the size of the structure with no domain
         * information. Below loop go through all counter_value array
         * to determine the number and size of each domain array element and
         * add it to the output buffer.
         */
        while (i < returned_values) {
                k = j;
                for (; k < j + element_size; k++)
                        *n += sprintf(buf + *n,  "%02x", (u8)arg->bytes[k]);
                *n += sprintf(buf + *n,  "\n");

                total_affinity_domain_ele = (u8)arg->bytes[k - 2] << 8 | (u8)arg->bytes[k - 3];
                size_of_each_affinity_domain_ele = (u8)arg->bytes[k] << 8 | (u8)arg->bytes[k - 1];

                for (l = 0; l < total_affinity_domain_ele; l++) {
                        for (m = 0; m < size_of_each_affinity_domain_ele; m++) {
                                *n += sprintf(buf + *n,  "%02x", (u8)arg->bytes[k]);
                                k++;
                        }
                        *n += sprintf(buf + *n,  "\n");
                }

                *n += sprintf(buf + *n,  "\n");
                i++;
                j = k;
        }

        *last_element = k;
}

static ssize_t affinity_domain_via_partition_show(struct device *dev, struct device_attribute *attr,
                                                        char *buf)
{
        struct hv_gpci_request_buffer *arg;
        unsigned long ret;
        size_t n = 0;
        size_t last_element = 0;
        u32 starting_index;

        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

        /*
         * Pass the counter request value 0xB1 corresponds to counter request
         * type 'Affinity_domain_information_by_partition',
         * to retrieve the system affinity domain by partition information.
         * starting_index value refers to the starting hardware
         * processor index.
         */
        arg->params.counter_request = cpu_to_be32(sysinfo_counter_request[AFFINITY_DOMAIN_VIA_PAR]);
        arg->params.starting_index = cpu_to_be32(0);

        ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
                        virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);

        if (!ret)
                goto parse_result;

        if (ret && (ret != H_PARAMETER))
                goto out;

        /*
         * ret value as 'H_PARAMETER' implies that the current buffer size
         * can't accommodate all the information, and a partial buffer
         * returned. To handle that, we need to make subsequent requests
         * with next starting index to retrieve additional (missing) data.
         * Below loop do subsequent hcalls with next starting index and add it
         * to buffer util we get all the information.
         */
        while (ret == H_PARAMETER) {
                affinity_domain_via_partition_result_parse(
                        be16_to_cpu(arg->params.returned_values) - 1,
                        be16_to_cpu(arg->params.cv_element_size), buf,
                        &last_element, &n, arg);

                if (n >= PAGE_SIZE) {
                        put_cpu_var(hv_gpci_reqb);
                        pr_debug("System information exceeds PAGE_SIZE\n");
                        return -EFBIG;
                }

                /*
                 * Since the starting index value is part of counter_value
                 * buffer elements, use the starting_index value in the last
                 * element and add 1 to make subsequent hcalls.
                 */
                starting_index = (u8)arg->bytes[last_element] << 8 |
                                (u8)arg->bytes[last_element + 1];

                memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);
                arg->params.counter_request = cpu_to_be32(
                                sysinfo_counter_request[AFFINITY_DOMAIN_VIA_PAR]);
                arg->params.starting_index = cpu_to_be32(starting_index);

                ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
                                virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);

                if (ret && (ret != H_PARAMETER))
                        goto out;
        }

parse_result:
        affinity_domain_via_partition_result_parse(
                be16_to_cpu(arg->params.returned_values),
                be16_to_cpu(arg->params.cv_element_size),
                buf, &last_element, &n, arg);

        put_cpu_var(hv_gpci_reqb);
        return n;

out:
        put_cpu_var(hv_gpci_reqb);

        /*
         * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL',
         * which means that the current buffer size cannot accommodate
         * all the information and a partial buffer returned.
         * hcall fails incase of ret value other than H_SUCCESS or H_PARAMETER.
         *
         * ret value as H_AUTHORITY implies that partition is not permitted to retrieve
         * performance information, and required to set
         * "Enable Performance Information Collection" option.
         */
        if (ret == H_AUTHORITY)
                return -EPERM;

        /*
         * hcall can fail with other possible ret value like H_PRIVILEGE/H_HARDWARE
         * because of invalid buffer-length/address or due to some hardware
         * error.
         */
        return -EIO;
}

static DEVICE_ATTR_RO(kernel_version);
static DEVICE_ATTR_RO(cpumask);

HV_CAPS_ATTR(version, "0x%x\n");
HV_CAPS_ATTR(ga, "%d\n");
HV_CAPS_ATTR(expanded, "%d\n");
HV_CAPS_ATTR(lab, "%d\n");
HV_CAPS_ATTR(collect_privileged, "%d\n");

static struct attribute *interface_attrs[] = {
        &dev_attr_kernel_version.attr,
        &hv_caps_attr_version.attr,
        &hv_caps_attr_ga.attr,
        &hv_caps_attr_expanded.attr,
        &hv_caps_attr_lab.attr,
        &hv_caps_attr_collect_privileged.attr,
        /*
         * This NULL is a placeholder for the processor_bus_topology
         * attribute, set in init function if applicable.
         */
        NULL,
        /*
         * This NULL is a placeholder for the processor_config
         * attribute, set in init function if applicable.
         */
        NULL,
        /*
         * This NULL is a placeholder for the affinity_domain_via_virtual_processor
         * attribute, set in init function if applicable.
         */
        NULL,
        /*
         * This NULL is a placeholder for the affinity_domain_via_domain
         * attribute, set in init function if applicable.
         */
        NULL,
        /*
         * This NULL is a placeholder for the affinity_domain_via_partition
         * attribute, set in init function if applicable.
         */
        NULL,
        NULL,
};

static struct attribute *cpumask_attrs[] = {
        &dev_attr_cpumask.attr,
        NULL,
};

static const struct attribute_group cpumask_attr_group = {
        .attrs = cpumask_attrs,
};

static const struct attribute_group interface_group = {
        .name = "interface",
        .attrs = interface_attrs,
};

static const struct attribute_group *attr_groups[] = {
        &format_group,
        &event_group,
        &interface_group,
        &cpumask_attr_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 hv_gpci_request_buffer *arg;

        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

        arg->params.counter_request = cpu_to_be32(req);
        arg->params.starting_index = cpu_to_be32(starting_index);
        arg->params.secondary_index = cpu_to_be16(secondary_index);
        arg->params.counter_info_version_in = version_in;

        ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
                        virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);

        /*
         * ret value as 'H_PARAMETER' with detail_rc as 'GEN_BUF_TOO_SMALL',
         * specifies that the current buffer size cannot accommodate
         * all the information and a partial buffer returned.
         * Since in this function we are only accessing data for a given starting index,
         * we don't need to accommodate whole data and can get required count by
         * accessing first entry data.
         * Hence hcall fails only incase the ret value is other than H_SUCCESS or
         * H_PARAMETER with detail_rc value as GEN_BUF_TOO_SMALL(0x1B).
         */
        if (ret == H_PARAMETER && be32_to_cpu(arg->params.detail_rc) == 0x1B)
                ret = 0;

        if (ret) {
                pr_devel("hcall failed: 0x%lx\n", ret);
                goto out;
        }

        /*
         * we verify offset and length are within the zeroed buffer at event
         * init.
         */
        count = 0;
        for (i = offset; i < offset + length; i++)
                count |= (u64)(arg->bytes[i]) << ((length - 1 - (i - offset)) * 8);

        *value = count;
out:
        put_cpu_var(hv_gpci_reqb);
        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));
}

static void h_gpci_event_stop(struct perf_event *event, int flags)
{
        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 int h_gpci_event_init(struct perf_event *event)
{
        u64 count;
        u8 length;
        unsigned long ret;

        /* Not our event */
        if (event->attr.type != event->pmu->type)
                return -ENOENT;

        /* config2 is unused */
        if (event->attr.config2) {
                pr_devel("config2 set when reserved\n");
                return -EINVAL;
        }

        /* no branch sampling */
        if (has_branch_stack(event))
                return -EOPNOTSUPP;

        length = event_get_length(event);
        if (length < 1 || length > 8) {
                pr_devel("length invalid\n");
                return -EINVAL;
        }

        /* last byte within the buffer? */
        if ((event_get_offset(event) + length) > HGPCI_MAX_DATA_BYTES) {
                pr_devel("request outside of buffer: %zu > %zu\n",
                                (size_t)event_get_offset(event) + length,
                                HGPCI_MAX_DATA_BYTES);
                return -EINVAL;
        }

        /* check if the request works... */
        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),
                                length,
                                &count);

        /*
         * ret value as H_AUTHORITY implies that partition is not permitted to retrieve
         * performance information, and required to set
         * "Enable Performance Information Collection" option.
         */
        if (ret == H_AUTHORITY)
                return -EPERM;

        if (ret) {
                pr_devel("gpci hcall failed\n");
                return -EINVAL;
        }

        return 0;
}

static 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_stop,
        .start       = h_gpci_event_start,
        .stop        = h_gpci_event_stop,
        .read        = h_gpci_event_update,
        .capabilities = PERF_PMU_CAP_NO_EXCLUDE,
};

static int ppc_hv_gpci_cpu_online(unsigned int cpu)
{
        if (cpumask_empty(&hv_gpci_cpumask))
                cpumask_set_cpu(cpu, &hv_gpci_cpumask);

        return 0;
}

static int ppc_hv_gpci_cpu_offline(unsigned int cpu)
{
        int target;

        /* Check if exiting cpu is used for collecting gpci events */
        if (!cpumask_test_and_clear_cpu(cpu, &hv_gpci_cpumask))
                return 0;

        /* Find a new cpu to collect gpci events */
        target = cpumask_last(cpu_active_mask);

        if (target < 0 || target >= nr_cpu_ids) {
                pr_err("hv_gpci: CPU hotplug init failed\n");
                return -1;
        }

        /* Migrate gpci events to the new target */
        cpumask_set_cpu(target, &hv_gpci_cpumask);
        perf_pmu_migrate_context(&h_gpci_pmu, cpu, target);

        return 0;
}

static int hv_gpci_cpu_hotplug_init(void)
{
        return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_HV_GPCI_ONLINE,
                          "perf/powerpc/hv_gcpi:online",
                          ppc_hv_gpci_cpu_online,
                          ppc_hv_gpci_cpu_offline);
}

static struct device_attribute *sysinfo_device_attr_create(int
                sysinfo_interface_group_index, u32 req)
{
        struct device_attribute *attr = NULL;
        unsigned long ret;
        struct hv_gpci_request_buffer *arg;

        if (sysinfo_interface_group_index < INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR ||
                        sysinfo_interface_group_index >= INTERFACE_NULL_ATTR) {
                pr_info("Wrong interface group index for system information\n");
                return NULL;
        }

        /* Check for given counter request value support */
        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

        arg->params.counter_request = cpu_to_be32(req);

        ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
                        virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);

        put_cpu_var(hv_gpci_reqb);

        /*
         * Add given counter request value attribute in the interface_attrs
         * attribute array, only for valid return types.
         */
        if (!ret || ret == H_AUTHORITY || ret == H_PARAMETER) {
                attr = kzalloc_obj(*attr);
                if (!attr)
                        return NULL;

                sysfs_attr_init(&attr->attr);
                attr->attr.mode = 0444;

                switch (sysinfo_interface_group_index) {
                case INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR:
                        attr->attr.name = "processor_bus_topology";
                        attr->show = processor_bus_topology_show;
                break;
                case INTERFACE_PROCESSOR_CONFIG_ATTR:
                        attr->attr.name = "processor_config";
                        attr->show = processor_config_show;
                break;
                case INTERFACE_AFFINITY_DOMAIN_VIA_VP_ATTR:
                        attr->attr.name = "affinity_domain_via_virtual_processor";
                        attr->show = affinity_domain_via_virtual_processor_show;
                break;
                case INTERFACE_AFFINITY_DOMAIN_VIA_DOM_ATTR:
                        attr->attr.name = "affinity_domain_via_domain";
                        attr->show = affinity_domain_via_domain_show;
                break;
                case INTERFACE_AFFINITY_DOMAIN_VIA_PAR_ATTR:
                        attr->attr.name = "affinity_domain_via_partition";
                        attr->show = affinity_domain_via_partition_show;
                break;
                }
        } else
                pr_devel("hcall failed, with error: 0x%lx\n", ret);

        return attr;
}

static void add_sysinfo_interface_files(void)
{
        int sysfs_count;
        struct device_attribute *attr[INTERFACE_NULL_ATTR - INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR];
        int i;

        sysfs_count = INTERFACE_NULL_ATTR - INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR;

        /* Get device attribute for a given counter request value */
        for (i = 0; i < sysfs_count; i++) {
                attr[i] = sysinfo_device_attr_create(i + INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR,
                                sysinfo_counter_request[i]);

                if (!attr[i])
                        goto out;
        }

        /* Add sysinfo interface attributes in the interface_attrs attribute array */
        for (i = 0; i < sysfs_count; i++)
                interface_attrs[i + INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR] = &attr[i]->attr;

        return;

out:
        /*
         * The sysinfo interface attributes will be added, only if hcall passed for
         * all the counter request values. Free the device attribute array incase
         * of any hcall failure.
         */
        if (i > 0) {
                while (i >= 0) {
                        kfree(attr[i]);
                        i--;
                }
        }
}

static int hv_gpci_init(void)
{
        int r;
        unsigned long hret;
        struct hv_perf_caps caps;
        struct hv_gpci_request_buffer *arg;

        hv_gpci_assert_offsets_correct();

        if (!firmware_has_feature(FW_FEATURE_LPAR)) {
                pr_debug("not a virtualized system, not enabling\n");
                return -ENODEV;
        }

        hret = hv_perf_caps_get(&caps);
        if (hret) {
                pr_debug("could not obtain capabilities, not enabling, rc=%ld\n",
                                hret);
                return -ENODEV;
        }

        /* init cpuhotplug */
        r = hv_gpci_cpu_hotplug_init();
        if (r)
                return r;

        /* sampling not supported */
        h_gpci_pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;

        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);

        /*
         * hcall H_GET_PERF_COUNTER_INFO populates the output
         * counter_info_version value based on the system hypervisor.
         * Pass the counter request 0x10 corresponds to request type
         * 'Dispatch_timebase_by_processor', to get the supported
         * counter_info_version.
         */
        arg->params.counter_request = cpu_to_be32(0x10);

        r = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
                        virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);
        if (r) {
                pr_devel("hcall failed, can't get supported counter_info_version: 0x%x\n", r);
                arg->params.counter_info_version_out = 0x8;
        }

        /*
         * Use counter_info_version_out value to assign
         * required hv-gpci event list.
         */
        if (arg->params.counter_info_version_out >= 0x8)
                event_group.attrs = hv_gpci_event_attrs;
        else
                event_group.attrs = hv_gpci_event_attrs_v6;

        put_cpu_var(hv_gpci_reqb);

        r = perf_pmu_register(&h_gpci_pmu, h_gpci_pmu.name, -1);
        if (r)
                return r;

        /* sysinfo interface files are only available for power10 and above platforms */
        if (PVR_VER(mfspr(SPRN_PVR)) >= PVR_POWER10)
                add_sysinfo_interface_files();

        return 0;
}

device_initcall(hv_gpci_init);