The PPTT describes CPUs and caches, as well as processor containers.
The ACPI table for MPAM describes the set of CPUs that can access an MSC
with the UID of a processor container.
Add a helper to find the processor container by its id, then walk
the possible CPUs to fill a cpumask with the CPUs that have this
processor container as a parent.
CC: Dave Martin <dave.martin@xxxxxxx>
Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
---
Changes since RFC:
* Dropped has_leaf_flag dodging of acpi_pptt_leaf_node()
* Added missing : in kernel-doc
* Made helper return void as this never actually returns an error.
---
drivers/acpi/pptt.c | 86 ++++++++++++++++++++++++++++++++++++++++++++
include/linux/acpi.h | 3 ++
2 files changed, 89 insertions(+)
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index 54676e3d82dd..4791ca2bdfac 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -298,6 +298,92 @@ static struct acpi_pptt_processor *acpi_find_processor_node(struct acpi_table_he
return NULL;
}
+/**
+ * acpi_pptt_get_child_cpus() - Find all the CPUs below a PPTT processor node
+ * @table_hdr: A reference to the PPTT table.
+ * @parent_node: A pointer to the processor node in the @table_hdr.
+ * @cpus: A cpumask to fill with the CPUs below @parent_node.
+ *
+ * Walks up the PPTT from every possible CPU to find if the provided
+ * @parent_node is a parent of this CPU.
+ */
+static void acpi_pptt_get_child_cpus(struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *parent_node,
+ cpumask_t *cpus)
+{
+ struct acpi_pptt_processor *cpu_node;
+ u32 acpi_id;
+ int cpu;
+
+ cpumask_clear(cpus);
+
+ for_each_possible_cpu(cpu) {
+ acpi_id = get_acpi_id_for_cpu(cpu);
+ cpu_node = acpi_find_processor_node(table_hdr, acpi_id);
+
+ while (cpu_node) {
+ if (cpu_node == parent_node) {
+ cpumask_set_cpu(cpu, cpus);
+ break;
+ }
+ cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
+ }
+ }
+}
+
+/**
+ * acpi_pptt_get_cpus_from_container() - Populate a cpumask with all CPUs in a
+ * processor containers
+ * @acpi_cpu_id: The UID of the processor container.
+ * @cpus: The resulting CPU mask.
+ *
+ * Find the specified Processor Container, and fill @cpus with all the cpus
+ * below it.
+ *
+ * Not all 'Processor' entries in the PPTT are either a CPU or a Processor
+ * Container, they may exist purely to describe a Private resource. CPUs
+ * have to be leaves, so a Processor Container is a non-leaf that has the
+ * 'ACPI Processor ID valid' flag set.
+ *
+ * Return: 0 for a complete walk, or an error if the mask is incomplete.
+ */
+void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, cpumask_t *cpus)
+{
+ struct acpi_pptt_processor *cpu_node;
+ struct acpi_table_header *table_hdr;
+ struct acpi_subtable_header *entry;
+ unsigned long table_end;
+ acpi_status status;
+ bool leaf_flag;
+ u32 proc_sz;
+
+ cpumask_clear(cpus);
+
+ status = acpi_get_table(ACPI_SIG_PPTT, 0, &table_hdr);
+ if (ACPI_FAILURE(status))
+ return;
+
+ table_end = (unsigned long)table_hdr + table_hdr->length;
+ entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr,
+ sizeof(struct acpi_table_pptt));
+ proc_sz = sizeof(struct acpi_pptt_processor);
+ while ((unsigned long)entry + proc_sz <= 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) {
+ leaf_flag = acpi_pptt_leaf_node(table_hdr, cpu_node);
+ if (!leaf_flag) {
+ if (cpu_node->acpi_processor_id == acpi_cpu_id)
+ acpi_pptt_get_child_cpus(table_hdr, cpu_node, cpus);
+ }
+ }
+ entry = ACPI_ADD_PTR(struct acpi_subtable_header, entry,
+ entry->length);
+ }
+
+ acpi_put_table(table_hdr);
+}
+
static u8 acpi_cache_type(enum cache_type type)
{
switch (type) {
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 1c5bb1e887cd..f97a9ff678cc 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1541,6 +1541,7 @@ int find_acpi_cpu_topology(unsigned int cpu, int level);
int find_acpi_cpu_topology_cluster(unsigned int cpu);
int find_acpi_cpu_topology_package(unsigned int cpu);
int find_acpi_cpu_topology_hetero_id(unsigned int cpu);
+void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, cpumask_t *cpus);
#else
static inline int acpi_pptt_cpu_is_thread(unsigned int cpu)
{
@@ -1562,6 +1563,8 @@ static inline int find_acpi_cpu_topology_hetero_id(unsigned int cpu)
{
return -EINVAL;
}
+static inline void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id,
+ cpumask_t *cpus) { }
#endif
void acpi_arch_init(void);
--
2.20.1
