On Thu, Oct 12, 2017 at 02:48:50PM -0500, 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.
I think this patch should be split ((1) topology (2) cache), it is doing
too much which makes it hard to review.
[...]
> +/* 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));
> +
> + 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);
> + }
A leaf node is a node with a valid acpi_id corresponding to an MADT
entry, right ? By the way, is this function really needed ?
> + 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));
> +
> + /* 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)) {
Is the leaf node check necessary ? Or you just need to check the
ACPI Processor ID valid flag (as discussed offline) ?
> + pr_debug("checking phy_cpu_id %d against acpi id %d\n",
> + acpi_cpu_id, cpu_node->acpi_processor_id);
Side note: I'd question (some of) these pr_debug() messages.
> + if (acpi_cpu_id == cpu_node->acpi_processor_id) {
> + /* found the correct entry */
> + pr_debug("match found!\n");
Like this one for instance.
> + return (struct acpi_pptt_processor *)entry;
> + }
> + }
> +
> + if (entry->length == 0) {
> + pr_err("Invalid zero length subtable\n");
> + break;
> + }
This should be moved at the beginning of the loop.
> + entry = (struct acpi_subtable_header *)
> + ((u8 *)entry + entry->length);
> + }
> +
> + 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)) {
I really do not understand what ACPI_PPTT_PHYSICAL_PACKAGE means and
more importantly, how it is actually used in this code.
This function is used to get a topology id (that is just a number for
a given topology level) for a given level starting from a given leaf
node.
Why do we care at all about 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;
> +}
> +
> +#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_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);
> + *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;
This would break !ARM64.
> + 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);
> + }
> + 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;
Ditto.
> + 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;
Ditto.
> + cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
> + if (cpu_node) {
> + cpu_node = acpi_find_processor_package_id(table, cpu_node,
> level);
If level is 0 there is nothing to do here.
> + /* Only the first level has a guaranteed id */
> + if (level == 0)
> + return cpu_node->acpi_processor_id;
> + return (int)((u8 *)cpu_node - (u8 *)table);
Please explain to me the rationale behind this. To me acpi_processor_id
is as good as the cpu_node offset in the table to describe the topology
id at a given level, why special case level 0.
On top of that, with this ID scheme, we would end up with
thread/core/cluster id potentially being non-sequential values
(depending on the PPTT table layout) which should not be a problem but
we'd better check how people are using them.
> + }
> + 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.
Add a kerneldoc style comment for an external interface.
> + */
> +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.
Ditto.
> + */
> +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;
This value is just a token - with no HW meaning whatsoever and that's
where I question the ACPI_PPTT_PHYSICAL_PACKAGE flag usage in retrieving
it, you are not looking for a packageid (which has no meaning whatsoever
anyway and I wonder why it was added to the specs at all) you are
looking for an id at a given level.
I will comment on the cache code separately - which deserves to
be in a separate patch to simplify the review, I avoided repeating
already reported review comments.
Lorenzo
