From ed2b664fcc8073c09394393756df3fc86977bbac Mon Sep 17 00:00:00 2001 From: Jeremy Linton Date: Wed, 26 Jun 2019 16:37:15 -0500 Subject: ACPI/PPTT: Modify node flag detection to find last IDENTICAL The ACPI specification implies that the IDENTICAL flag should be set on all non leaf nodes where the children are identical. This means that we need to be searching for the last node with the identical flag set rather than the first one. Since this flag is also dependent on the table revision, we need to add a bit of extra code to verify the table revision, and the next node's state in the traversal. Since we want to avoid function pointers here, lets just special case the IDENTICAL flag. Acked-by: Rafael J. Wysocki Tested-by: Hanjun Guo Reviewed-by: Sudeep Holla Signed-off-by: Jeremy Linton Signed-off-by: Will Deacon --- drivers/acpi/pptt.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) (limited to 'drivers/acpi') diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c index b72e6afaa8fb..05344413f199 100644 --- a/drivers/acpi/pptt.c +++ b/drivers/acpi/pptt.c @@ -432,17 +432,40 @@ static void cache_setup_acpi_cpu(struct acpi_table_header *table, } } +static bool flag_identical(struct acpi_table_header *table_hdr, + struct acpi_pptt_processor *cpu) +{ + struct acpi_pptt_processor *next; + + /* heterogeneous machines must use PPTT revision > 1 */ + if (table_hdr->revision < 2) + return false; + + /* Locate the last node in the tree with IDENTICAL set */ + if (cpu->flags & ACPI_PPTT_ACPI_IDENTICAL) { + next = fetch_pptt_node(table_hdr, cpu->parent); + if (!(next && next->flags & ACPI_PPTT_ACPI_IDENTICAL)) + return true; + } + + return false; +} + /* Passing level values greater than this will result in search termination */ #define PPTT_ABORT_PACKAGE 0xFF -static struct acpi_pptt_processor *acpi_find_processor_package_id(struct acpi_table_header *table_hdr, - struct acpi_pptt_processor *cpu, - int level, int flag) +static struct acpi_pptt_processor *acpi_find_processor_tag(struct acpi_table_header *table_hdr, + struct acpi_pptt_processor *cpu, + int level, int flag) { struct acpi_pptt_processor *prev_node; while (cpu && level) { - if (cpu->flags & flag) + /* special case the identical flag to find last identical */ + if (flag == ACPI_PPTT_ACPI_IDENTICAL) { + if (flag_identical(table_hdr, cpu)) + break; + } else if (cpu->flags & flag) break; pr_debug("level %d\n", level); prev_node = fetch_pptt_node(table_hdr, cpu->parent); @@ -480,8 +503,8 @@ static int topology_get_acpi_cpu_tag(struct acpi_table_header *table, cpu_node = acpi_find_processor_node(table, acpi_cpu_id); if (cpu_node) { - cpu_node = acpi_find_processor_package_id(table, cpu_node, - level, flag); + cpu_node = acpi_find_processor_tag(table, cpu_node, + level, flag); /* * As per specification if the processor structure represents * an actual processor, then ACPI processor ID must be valid. -- cgit v1.2.3 From 56855a99f3d0d1e9f1f4e24f5851f9bf14c83296 Mon Sep 17 00:00:00 2001 From: Jeremy Linton Date: Wed, 26 Jun 2019 16:37:16 -0500 Subject: ACPI/PPTT: Add function to return ACPI 6.3 Identical tokens ACPI 6.3 adds a flag to indicate that child nodes are all identical cores. This is useful to authoritatively determine if a set of (possibly offline) cores are identical or not. Since the flag doesn't give us a unique id we can generate one and use it to create bitmaps of sibling nodes, or simply in a loop to determine if a subset of cores are identical. Acked-by: Rafael J. Wysocki Tested-by: Hanjun Guo Reviewed-by: Sudeep Holla Signed-off-by: Jeremy Linton Signed-off-by: Will Deacon --- drivers/acpi/pptt.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'drivers/acpi') diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c index 05344413f199..1e7ac0bd0d3a 100644 --- a/drivers/acpi/pptt.c +++ b/drivers/acpi/pptt.c @@ -683,3 +683,29 @@ int find_acpi_cpu_topology_package(unsigned int cpu) return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, ACPI_PPTT_PHYSICAL_PACKAGE); } + +/** + * find_acpi_cpu_topology_hetero_id() - Get a core architecture tag + * @cpu: Kernel logical CPU number + * + * Determine a unique heterogeneous tag for the given CPU. CPUs with the same + * implementation should have matching tags. + * + * The returned tag can be used to group peers with identical implementation. + * + * The search terminates when a level is found with the identical implementation + * flag set or we reach a root node. + * + * Due to limitations in the PPTT data structure, there may be rare situations + * where two cores in a heterogeneous machine may be identical, but won't have + * the same tag. + * + * Return: -ENOENT if the PPTT doesn't exist, or the CPU cannot be found. + * Otherwise returns a value which represents a group of identical cores + * similar to this CPU. + */ +int find_acpi_cpu_topology_hetero_id(unsigned int cpu) +{ + return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, + ACPI_PPTT_ACPI_IDENTICAL); +} -- cgit v1.2.3