[RFC 3/4] ACPI/PPTT: Add Processor Properties Topology Table parsing
Jeremy Linton
jeremy.linton at arm.com
Wed Sep 6 13:39:09 PDT 2017
Hi,
On 09/06/2017 05:34 AM, Xiongfeng Wang wrote:
> Hi Jeremy,
>
> On 2017/8/5 8:11, 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.
>>
>> Signed-off-by: Jeremy Linton <jeremy.linton at arm.com>
>> ---
>> drivers/acpi/arm64/pptt.c | 389 ++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 389 insertions(+)
>> create mode 100644 drivers/acpi/arm64/pptt.c
>>
>> diff --git a/drivers/acpi/arm64/pptt.c b/drivers/acpi/arm64/pptt.c
>> new file mode 100644
>> index 0000000..e1ab77d
>> --- /dev/null
>> +++ b/drivers/acpi/arm64/pptt.c
>> @@ -0,0 +1,389 @@
>> +/*
>> + * 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);
>> +
>> + 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);
>> +
>> + 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 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;
>> +}
>> +
>> +/*
>> + * 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));
>> +
>> + /* 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) &&
>> + (cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID)) {
>> + 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;
>> + }
>> + entry = (struct acpi_subtable_header *)
>> + ((u8 *)entry + entry->length);
>> + }
>> + return NULL;
>> +}
>> +
>> +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;
>> +}
>> +
>> +#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)
>> +#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)
>> +
>> +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_err("Unknown cache type, assume unified\n");
> I think we may need a 'pr_debug' here instead of 'pr_err'.
> The register CLIDR usually only describe the L1 or L2 cache of a core.
> Cache level described by CLIDR is often smaller than described by PPTT.
> The cache_type not described by CLIDR will be CACHE_TYPE_NOCACHE, which will
> cause a error info print here. This scene is very common. So I think
> a 'pr_debug' may be better.
That is a good point, thanks.
>
>> + 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)
>> +{
>> + 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);
>> + 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)
>> +{
>> + this_leaf->of_node = (struct device_node *)found_cache;
>> + 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);
>> + }
>> + 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);
>> + }
>> +}
>> +
>> +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;
>> +
>> + 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);
>> + pr_debug("found = %p\n", found_cache);
>> + if (found_cache)
>> + update_cache_properties(this_leaf, found_cache);
>> +
>> + index++;
>> + }
>> +}
>> +
>> +/*
>> + * 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 0;
>> +}
>>
>
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