Message-ID: <47852c78-047e-4245-ac9a-3b6b5db3ed18@arm.com>
Date:   Fri, 13 Oct 2017 14:58:26 -0500
From:   Jeremy Linton <jeremy.linton@....com>
To:     tn <Tomasz.Nowicki@...iumnetworks.com>, linux-acpi@...r.kernel.org
Cc:     mark.rutland@....com, Jonathan.Zhang@...ium.com,
        Jayachandran.Nair@...ium.com, lorenzo.pieralisi@....com,
        catalin.marinas@....com, gregkh@...uxfoundation.org,
        jhugo@...eaurora.org, rjw@...ysocki.net, linux-pm@...r.kernel.org,
        will.deacon@....com, linux-kernel@...r.kernel.org, ahs3@...hat.com,
        viresh.kumar@...aro.org, hanjun.guo@...aro.org,
        sudeep.holla@....com, austinwc@...eaurora.org,
        wangxiongfeng2@...wei.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 1/7] ACPI/PPTT: Add Processor Properties Topology Table
 parsing

Hi,

On 10/13/2017 09:23 AM, tn wrote:
> Hi Jeremy,
> 
> On 12.10.2017 21:48, Jeremy Linton wrote:
>> ACPI 6.2 adds a new table, which describes how processing units
>> are related to each other in tree like fashion. Caches are
>> also sprinkled throughout the tree and describe the properties
>> of the caches in relation to other caches and processing units.
>>
>> Add the code to parse the cache hierarchy and report the total
>> number of levels of cache for a given core using
>> acpi_find_last_cache_level() as well as fill out the individual
>> cores cache information with cache_setup_acpi() once the
>> cpu_cacheinfo structure has been populated by the arch specific
>> code.
>>
>> Further, report peers in the topology using setup_acpi_cpu_topology()
>> to report a unique ID for each processing unit at a given level
>> in the tree. These unique id's can then be used to match related
>> processing units which exist as threads, COD (clusters
>> on die), within a given package, etc.
>>
>> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
>> ---
>>   drivers/acpi/pptt.c | 485 
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 485 insertions(+)
>>   create mode 100644 drivers/acpi/pptt.c
>>
>> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
>> new file mode 100644
>> index 000000000000..c86715fed4a7
>> --- /dev/null
>> +++ b/drivers/acpi/pptt.c
>> @@ -0,1 +1,485 @@
>> +/*
>> + * Copyright (C) 2017, ARM
>> + *
>> + * This program is free software; you can redistribute it and/or 
>> modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but 
>> WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public 
>> License for
>> + * more details.
>> + *
>> + * This file implements parsing of Processor Properties Topology 
>> Table (PPTT)
>> + * which is optionally used to describe the processor and cache 
>> topology.
>> + * Due to the relative pointers used throughout the table, this doesn't
>> + * leverage the existing subtable parsing in the kernel.
>> + */
>> +#define pr_fmt(fmt) "ACPI PPTT: " fmt
>> +
>> +#include <linux/acpi.h>
>> +#include <linux/cacheinfo.h>
>> +#include <acpi/processor.h>
>> +
>> +/*
>> + * Given the PPTT table, find and verify that the subtable entry
>> + * is located within the table
>> + */
>> +static struct acpi_subtable_header *fetch_pptt_subtable(
>> +    struct acpi_table_header *table_hdr, u32 pptt_ref)
>> +{
>> +    struct acpi_subtable_header *entry;
>> +
>> +    /* there isn't a subtable at reference 0 */
>> +    if (!pptt_ref)
>> +        return NULL;
>> +
>> +    if (pptt_ref + sizeof(struct acpi_subtable_header) > 
>> table_hdr->length)
>> +        return NULL;
>> +
>> +    entry = (struct acpi_subtable_header *)((u8 *)table_hdr + pptt_ref);
> 
> You can use ACPI_ADD_PTR() here.

Hmmm, that is a useful macro.


> 
>> +
>> +    if (pptt_ref + entry->length > table_hdr->length)
>> +        return NULL;
>> +
>> +    return entry;
>> +}
>> +
>> +static struct acpi_pptt_processor *fetch_pptt_node(
>> +    struct acpi_table_header *table_hdr, u32 pptt_ref)
>> +{
>> +    return (struct acpi_pptt_processor 
>> *)fetch_pptt_subtable(table_hdr, pptt_ref);
>> +}
>> +
>> +static struct acpi_pptt_cache *fetch_pptt_cache(
>> +    struct acpi_table_header *table_hdr, u32 pptt_ref)
>> +{
>> +    return (struct acpi_pptt_cache *)fetch_pptt_subtable(table_hdr, 
>> pptt_ref);
>> +}
>> +
>> +static struct acpi_subtable_header *acpi_get_pptt_resource(
>> +    struct acpi_table_header *table_hdr,
>> +    struct acpi_pptt_processor *node, int resource)
>> +{
>> +    u32 ref;
>> +
>> +    if (resource >= node->number_of_priv_resources)
>> +        return NULL;
>> +
>> +    ref = *(u32 *)((u8 *)node + sizeof(struct acpi_pptt_processor) +
>> +              sizeof(u32) * resource);
> 
> ACPI_ADD_PTR()
> 
>> +
>> +    return fetch_pptt_subtable(table_hdr, ref);
>> +}
>> +
>> +/*
>> + * given a pptt resource, verify that it is a cache node, then walk
>> + * down each level of caches, counting how many levels are found
>> + * as well as checking the cache type (icache, dcache, unified). If a
>> + * level & type match, then we set found, and continue the search.
>> + * Once the entire cache branch has been walked return its max
>> + * depth.
>> + */
>> +static int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
>> +                int local_level,
>> +                struct acpi_subtable_header *res,
>> +                struct acpi_pptt_cache **found,
>> +                int level, int type)
>> +{
>> +    struct acpi_pptt_cache *cache;
>> +
>> +    if (res->type != ACPI_PPTT_TYPE_CACHE)
>> +        return 0;
>> +
>> +    cache = (struct acpi_pptt_cache *) res;
>> +    while (cache) {
>> +        local_level++;
>> +
>> +        if ((local_level == level) &&
>> +            (cache->flags & ACPI_PPTT_CACHE_TYPE_VALID) &&
>> +            ((cache->attributes & ACPI_PPTT_MASK_CACHE_TYPE) == type)) {
>> +            if (*found != NULL)
>> +                pr_err("Found duplicate cache level/type unable to 
>> determine uniqueness\n");
>> +
>> +            pr_debug("Found cache @ level %d\n", level);
>> +            *found = cache;
>> +            /*
>> +             * continue looking at this node's resource list
>> +             * to verify that we don't find a duplicate
>> +             * cache node.
>> +             */
>> +        }
>> +        cache = fetch_pptt_cache(table_hdr, cache->next_level_of_cache);
>> +    }
>> +    return local_level;
>> +}
>> +
>> +/*
>> + * Given a CPU node look for cache levels that exist at this level, 
>> and then
>> + * for each cache node, count how many levels exist below (logically 
>> above) it.
>> + * If a level and type are specified, and we find that level/type, abort
>> + * processing and return the acpi_pptt_cache structure.
>> + */
>> +static struct acpi_pptt_cache *acpi_find_cache_level(
>> +    struct acpi_table_header *table_hdr,
>> +    struct acpi_pptt_processor *cpu_node,
>> +    int *starting_level, int level, int type)
>> +{
>> +    struct acpi_subtable_header *res;
>> +    int number_of_levels = *starting_level;
>> +    int resource = 0;
>> +    struct acpi_pptt_cache *ret = NULL;
>> +    int local_level;
>> +
>> +    /* walk down from the processor node */
>> +    while ((res = acpi_get_pptt_resource(table_hdr, cpu_node, 
>> resource))) {
>> +        resource++;
>> +
>> +        local_level = acpi_pptt_walk_cache(table_hdr, *starting_level,
>> +                           res, &ret, level, type);
>> +        /*
>> +         * we are looking for the max depth. Since its potentially
>> +         * possible for a given node to have resources with differing
>> +         * depths verify that the depth we have found is the largest.
>> +         */
>> +        if (number_of_levels < local_level)
>> +            number_of_levels = local_level;
>> +    }
>> +    if (number_of_levels > *starting_level)
>> +        *starting_level = number_of_levels;
>> +
>> +    return ret;
>> +}
>> +
>> +/*
>> + * given a processor node containing a processing unit, walk into it 
>> and count
>> + * how many levels exist solely for it, and then walk up each level 
>> until we hit
>> + * the root node (ignore the package level because it may be possible 
>> to have
>> + * caches that exist across packages). Count the number of cache 
>> levels that
>> + * exist at each level on the way up.
>> + */
>> +static int acpi_process_node(struct acpi_table_header *table_hdr,
>> +                 struct acpi_pptt_processor *cpu_node)
>> +{
>> +    int total_levels = 0;
>> +
>> +    do {
>> +        acpi_find_cache_level(table_hdr, cpu_node, &total_levels, 0, 0);
>> +        cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
>> +    } while (cpu_node);
>> +
>> +    return total_levels;
>> +}
>> +
>> +/* determine if the given node is a leaf node */
>> +static int acpi_pptt_leaf_node(struct acpi_table_header *table_hdr,
>> +                   struct acpi_pptt_processor *node)
>> +{
>> +    struct acpi_subtable_header *entry;
>> +    unsigned long table_end;
>> +    u32 node_entry;
>> +    struct acpi_pptt_processor *cpu_node;
>> +
>> +    table_end = (unsigned long)table_hdr + table_hdr->length;
>> +    node_entry = (u32)((u8 *)node - (u8 *)table_hdr);
>> +    entry = (struct acpi_subtable_header *)((u8 *)table_hdr +
>> +                        sizeof(struct acpi_table_pptt));
> 
> ACPI_ADD_PTR()
> 
>> +
>> +    while (((unsigned long)entry) + sizeof(struct 
>> acpi_subtable_header) < table_end) {
>> +        cpu_node = (struct acpi_pptt_processor *)entry;
>> +        if ((entry->type == ACPI_PPTT_TYPE_PROCESSOR) &&
>> +            (cpu_node->parent == node_entry))
>> +            return 0;
>> +        entry = (struct acpi_subtable_header *)((u8 *)entry + 
>> entry->length);
>> +    }
>> +    return 1;
>> +}
>> +
>> +/*
>> + * Find the subtable entry describing the provided processor
>> + */
>> +static struct acpi_pptt_processor *acpi_find_processor_node(
>> +    struct acpi_table_header *table_hdr,
>> +    u32 acpi_cpu_id)
>> +{
>> +    struct acpi_subtable_header *entry;
>> +    unsigned long table_end;
>> +    struct acpi_pptt_processor *cpu_node;
>> +
>> +    table_end = (unsigned long)table_hdr + table_hdr->length;
>> +    entry = (struct acpi_subtable_header *)((u8 *)table_hdr +
>> +                        sizeof(struct acpi_table_pptt));
> 
> ACPI_ADD_PTR()
> 
>> +
>> +    /* find the processor structure associated with this cpuid */
>> +    while (((unsigned long)entry) + sizeof(struct 
>> acpi_subtable_header) < table_end) {
>> +        cpu_node = (struct acpi_pptt_processor *)entry;
>> +
>> +        if ((entry->type == ACPI_PPTT_TYPE_PROCESSOR) &&
>> +            acpi_pptt_leaf_node(table_hdr, cpu_node)) {
>> +            pr_debug("checking phy_cpu_id %d against acpi id %d\n",
>> +                 acpi_cpu_id, cpu_node->acpi_processor_id);
>> +            if (acpi_cpu_id == cpu_node->acpi_processor_id) {
>> +                /* found the correct entry */
>> +                pr_debug("match found!\n");
>> +                return (struct acpi_pptt_processor *)entry;
>> +            }
>> +        }
>> +
>> +        if (entry->length == 0) {
>> +            pr_err("Invalid zero length subtable\n");
>> +            break;
>> +        }
> 
> For a better table content validation, this could be done at the 
> beginning of the loop, like that:
> 
> if (WARN_TAINT(entry->length == 0, TAINT_FIRMWARE_WORKAROUND,
>         "Invalid zero length subtable, bad PPTT table!\n"))
>              break;
> 
> 
>> +        entry = (struct acpi_subtable_header *)
>> +            ((u8 *)entry + entry->length);
> 
> ACPI_ADD_PTR()
> 
>> +    }
>> +
>> +    return NULL;
>> +}
>> +
>> +/*
>> + * Given a acpi_pptt_processor node, walk up until we identify the
>> + * package that the node is associated with or we run out of levels
>> + * to request.
>> + */
>> +static struct acpi_pptt_processor *acpi_find_processor_package_id(
>> +    struct acpi_table_header *table_hdr,
>> +    struct acpi_pptt_processor *cpu,
>> +    int level)
>> +{
>> +    struct acpi_pptt_processor *prev_node;
>> +
>> +    while (cpu && level && !(cpu->flags & ACPI_PPTT_PHYSICAL_PACKAGE)) {
>> +        pr_debug("level %d\n", level);
>> +        prev_node = fetch_pptt_node(table_hdr, cpu->parent);
>> +        if (prev_node == NULL)
>> +            break;
>> +        cpu = prev_node;
>> +        level--;
>> +    }
>> +    return cpu;
>> +}
>> +
>> +static int acpi_parse_pptt(struct acpi_table_header *table_hdr, u32 
>> acpi_cpu_id)
>> +{
>> +    int number_of_levels = 0;
>> +    struct acpi_pptt_processor *cpu;
>> +
>> +    cpu = acpi_find_processor_node(table_hdr, acpi_cpu_id);
>> +    if (cpu)
>> +        number_of_levels = acpi_process_node(table_hdr, cpu);
>> +
>> +    return number_of_levels;
>> +}
>> +
> 
> Based on ACPI spec 6.2:
> 
>> +#define ACPI_6_2_CACHE_TYPE_DATA              (0x0)
>> +#define ACPI_6_2_CACHE_TYPE_INSTR              (1<<2)
>> +#define ACPI_6_2_CACHE_TYPE_UNIFIED              (1<<3)
> 
> Bits:3:2: Cache type:
> 0x0 Data
> 0x1 Instruction
> 0x2 or 0x3 Indicate a unified cache

Originally I was trying to do something more clever than the switch 
(given the less than optimal bit definitions), but the result wasn't as 
clear as the switch, so I just plugged that in but forgot about the 3rd 
case.

> 
>> +#define ACPI_6_2_CACHE_POLICY_WB              (0x0)
>> +#define ACPI_6_2_CACHE_POLICY_WT              (1<<4)
>> +#define ACPI_6_2_CACHE_READ_ALLOCATE              (0x0)
>> +#define ACPI_6_2_CACHE_WRITE_ALLOCATE              (0x01)
>> +#define ACPI_6_2_CACHE_RW_ALLOCATE              (0x02)
> 
> Bits 1:0: Allocation type
> 0x0 - Read allocate
> 0x1 - Write allocate
> 0x2 or 0x03 indicate Read and Write allocate
> 
> BTW, why these are not part of ACPICA code (actbl1.h header) and have 
> ACPI_PPTT prefixes?

Well I guess they probably should be the only question is how one goes 
about defining the duplicates..

AKA:

#define ACPI_PPTT_CACHE_RW_ALLOCATE              (0x02)
#define ACPI_PPTT_CACHE_RW_ALLOCATE_ALT          (0x03)

> 
>> +
>> +static u8 acpi_cache_type(enum cache_type type)
>> +{
>> +    switch (type) {
>> +    case CACHE_TYPE_DATA:
>> +        pr_debug("Looking for data cache\n");
>> +        return ACPI_6_2_CACHE_TYPE_DATA;
>> +    case CACHE_TYPE_INST:
>> +        pr_debug("Looking for instruction cache\n");
>> +        return ACPI_6_2_CACHE_TYPE_INSTR;
>> +    default:
>> +        pr_debug("Unknown cache type, assume unified\n");
>> +    case CACHE_TYPE_UNIFIED:
>> +        pr_debug("Looking for unified cache\n");
>> +        return ACPI_6_2_CACHE_TYPE_UNIFIED;
>> +    }
>> +}
>> +
>> +/* find the ACPI node describing the cache type/level for the given 
>> CPU */
>> +static struct acpi_pptt_cache *acpi_find_cache_node(
>> +    struct acpi_table_header *table_hdr, u32 acpi_cpu_id,
>> +    enum cache_type type, unsigned int level,
>> +    struct acpi_pptt_processor **node)
>> +{
>> +    int total_levels = 0;
>> +    struct acpi_pptt_cache *found = NULL;
>> +    struct acpi_pptt_processor *cpu_node;
>> +    u8 acpi_type = acpi_cache_type(type);
>> +
>> +    pr_debug("Looking for CPU %d's level %d cache type %d\n",
>> +         acpi_cpu_id, level, acpi_type);
>> +
>> +    cpu_node = acpi_find_processor_node(table_hdr, acpi_cpu_id);
>> +    if (!cpu_node)
>> +        return NULL;
>> +
>> +    do {
>> +        found = acpi_find_cache_level(table_hdr, cpu_node, 
>> &total_levels, level, acpi_type);
> 
> Please align line to 80 characters at maximum.

ok,

> 
>> +        *node = cpu_node;
>> +        cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
>> +    } while ((cpu_node) && (!found));
>> +
>> +    return found;
>> +}
>> +
>> +int acpi_find_last_cache_level(unsigned int cpu)
>> +{
>> +    u32 acpi_cpu_id;
>> +    struct acpi_table_header *table;
>> +    int number_of_levels = 0;
>> +    acpi_status status;
>> +
>> +    pr_debug("Cache Setup find last level cpu=%d\n", cpu);
>> +
>> +    acpi_cpu_id = acpi_cpu_get_madt_gicc(cpu)->uid;
>> +    status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
>> +    if (ACPI_FAILURE(status)) {
>> +        pr_err_once("No PPTT table found, cache topology may be 
>> inaccurate\n");
>> +    } else {
>> +        number_of_levels = acpi_parse_pptt(table, acpi_cpu_id);
>> +        acpi_put_table(table);
>> +    }
>> +    pr_debug("Cache Setup find last level level=%d\n", 
>> number_of_levels);
>> +
>> +    return number_of_levels;
>> +}
>> +
>> +/*
>> + * The ACPI spec implies that the fields in the cache structures are 
>> used to
>> + * extend and correct the information probed from the hardware. In 
>> the case
>> + * of arm64 the CCSIDR probing has been removed because it might be 
>> incorrect.
>> + */
>> +static void update_cache_properties(struct cacheinfo *this_leaf,
>> +                    struct acpi_pptt_cache *found_cache,
>> +                    struct acpi_pptt_processor *cpu_node)
>> +{
>> +    if (found_cache->flags & ACPI_PPTT_SIZE_PROPERTY_VALID)
>> +        this_leaf->size = found_cache->size;
>> +    if (found_cache->flags & ACPI_PPTT_LINE_SIZE_VALID)
>> +        this_leaf->coherency_line_size = found_cache->line_size;
>> +    if (found_cache->flags & ACPI_PPTT_NUMBER_OF_SETS_VALID)
>> +        this_leaf->number_of_sets = found_cache->number_of_sets;
>> +    if (found_cache->flags & ACPI_PPTT_ASSOCIATIVITY_VALID)
>> +        this_leaf->ways_of_associativity = found_cache->associativity;
>> +    if (found_cache->flags & ACPI_PPTT_WRITE_POLICY_VALID)
>> +        switch (found_cache->attributes & ACPI_PPTT_MASK_WRITE_POLICY) {
>> +        case ACPI_6_2_CACHE_POLICY_WT:
>> +            this_leaf->attributes = CACHE_WRITE_THROUGH;
>> +            break;
>> +        case ACPI_6_2_CACHE_POLICY_WB:
>> +            this_leaf->attributes = CACHE_WRITE_BACK;
>> +            break;
>> +        default:
>> +            pr_err("Unknown ACPI cache policy %d\n",
>> +                  found_cache->attributes & 
>> ACPI_PPTT_MASK_WRITE_POLICY);
>> +        }
> 
> The 'default' case can never happen, please remove dead code.

Ok,

> 
>> +    if (found_cache->flags & ACPI_PPTT_ALLOCATION_TYPE_VALID)
>> +        switch (found_cache->attributes & 
>> ACPI_PPTT_MASK_ALLOCATION_TYPE) {
>> +        case ACPI_6_2_CACHE_READ_ALLOCATE:
>> +            this_leaf->attributes |= CACHE_READ_ALLOCATE;
>> +            break;
>> +        case ACPI_6_2_CACHE_WRITE_ALLOCATE:
>> +            this_leaf->attributes |= CACHE_WRITE_ALLOCATE;
>> +            break;
>> +        case ACPI_6_2_CACHE_RW_ALLOCATE:
>> +            this_leaf->attributes |=
>> +                CACHE_READ_ALLOCATE|CACHE_WRITE_ALLOCATE;
>> +            break;
>> +        default:
>> +            pr_err("Unknown ACPI cache allocation policy %d\n",
>> +               found_cache->attributes & 
>> ACPI_PPTT_MASK_ALLOCATION_TYPE);
>> +        }
> 
> Same here if you fix bits definitions.

Sure,

> 
>> +}
>> +
>> +static void cache_setup_acpi_cpu(struct acpi_table_header *table,
>> +                 unsigned int cpu)
>> +{
>> +    struct acpi_pptt_cache *found_cache;
>> +    struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
>> +    u32 acpi_cpu_id = acpi_cpu_get_madt_gicc(cpu)->uid;
>> +    struct cacheinfo *this_leaf;
>> +    unsigned int index = 0;
>> +    struct acpi_pptt_processor *cpu_node = NULL;
>> +
>> +    while (index < get_cpu_cacheinfo(cpu)->num_leaves) {
>> +        this_leaf = this_cpu_ci->info_list + index;
>> +        found_cache = acpi_find_cache_node(table, acpi_cpu_id,
>> +                           this_leaf->type,
>> +                           this_leaf->level,
>> +                           &cpu_node);
>> +        pr_debug("found = %p %p\n", found_cache, cpu_node);
>> +        if (found_cache)
>> +            update_cache_properties(this_leaf,
>> +                        found_cache,
>> +                        cpu_node);
>> +
>> +        index++;
>> +    }
>> +}
>> +
>> +static int topology_setup_acpi_cpu(struct acpi_table_header *table,
>> +                    unsigned int cpu, int level)
>> +{
>> +    struct acpi_pptt_processor *cpu_node;
>> +    u32 acpi_cpu_id = acpi_cpu_get_madt_gicc(cpu)->uid;
>> +
>> +    cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
>> +    if (cpu_node) {
>> +        cpu_node = acpi_find_processor_package_id(table, cpu_node, 
>> level);
>> +        /* Only the first level has a guaranteed id */
>> +        if (level == 0)
>> +            return cpu_node->acpi_processor_id;
>> +        return (int)((u8 *)cpu_node - (u8 *)table);
>> +    }
>> +    pr_err_once("PPTT table found, but unable to locate core for %d\n",
>> +            cpu);
>> +    return -ENOENT;
>> +}
>> +
>> +/*
>> + * simply assign a ACPI cache entry to each known CPU cache entry
>> + * determining which entries are shared is done later.
>> + */
>> +int cache_setup_acpi(unsigned int cpu)
>> +{
>> +    struct acpi_table_header *table;
>> +    acpi_status status;
>> +
>> +    pr_debug("Cache Setup ACPI cpu %d\n", cpu);
>> +
>> +    status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
>> +    if (ACPI_FAILURE(status)) {
>> +        pr_err_once("No PPTT table found, cache topology may be 
>> inaccurate\n");
>> +        return -ENOENT;
>> +    }
>> +
>> +    cache_setup_acpi_cpu(table, cpu);
>> +    acpi_put_table(table);
>> +
>> +    return status;
>> +}
>> +
>> +/*
>> + * Determine a topology unique ID for each 
>> thread/core/cluster/socket/etc.
>> + * This ID can then be used to group peers.
>> + */
>> +int setup_acpi_cpu_topology(unsigned int cpu, int level)
>> +{
>> +    struct acpi_table_header *table;
>> +    acpi_status status;
>> +    int retval;
>> +
>> +    status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
>> +    if (ACPI_FAILURE(status)) {
>> +        pr_err_once("No PPTT table found, cpu topology may be 
>> inaccurate\n");
>> +        return -ENOENT;
>> +    }
>> +    retval = topology_setup_acpi_cpu(table, cpu, level);
>> +    pr_debug("Topology Setup ACPI cpu %d, level %d ret = %d\n",
>> +         cpu, level, retval);
>> +    acpi_put_table(table);
>> +
>> +    return retval;
>> +}
>>
> 
> Thanks,
> Tomasz
> 

Thanks for taking the time to look at this.

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