Hi Jonathan,

On 16/07/2025 17:24, Jonathan Cameron wrote:

On Fri, 11 Jul 2025 18:36:20 +0000
James Morse [off-list ref] wrote:

quoted

MPAM identifies CPUs by the cache_id in the PPTT cache structure.

The driver needs to know which CPUs are associated with the cache,
the CPUs may not all be online, so cacheinfo does not have the
information.

Add a helper to pull this information out of the PPTT.

quoted

diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index f53748a5df19..81f7ac18c023 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c

@@ -985,3 +985,73 @@ int find_acpi_cache_level_from_id(u32 cache_id)

quoted

+int acpi_pptt_get_cpumask_from_cache_id(u32 cache_id, cpumask_t *cpus)
+{
+	u32 acpi_cpu_id;
+	acpi_status status;
+	int level, cpu, num_levels;
+	struct acpi_pptt_cache *cache;
+	struct acpi_table_header *table;
+	struct acpi_pptt_cache_v1 *cache_v1;
+	struct acpi_pptt_processor *cpu_node;
+
+	cpumask_clear(cpus);
+
+	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);

Similar suggestions to previous patch apply here as well.

Done!

quoted

+	if (ACPI_FAILURE(status)) {
+		acpi_pptt_warn_missing();
+		return -ENOENT;
+	}
+
+	if (table->revision < 3) {
+		acpi_put_table(table);
+		return -ENOENT;
+	}
+
+	/*
+	 * If we found the cache first, we'd still need to walk from each cpu.
+	 */
+	for_each_possible_cpu(cpu) {
+		acpi_cpu_id = get_acpi_id_for_cpu(cpu);
+		cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
+		if (!cpu_node)
+			break;
+		acpi_count_levels(table, cpu_node, &num_levels, NULL);
+
+		/* Start at 1 for L1 */
+		for (level = 1; level <= num_levels; level++) {
+			cache = acpi_find_cache_node(table, acpi_cpu_id,
+						     ACPI_PPTT_CACHE_TYPE_UNIFIED,
+						     level, &cpu_node);
+			if (!cache)
+				continue;
+
+			cache_v1 = ACPI_ADD_PTR(struct acpi_pptt_cache_v1,
+						cache,
+						sizeof(struct acpi_pptt_cache));
+
+			if (cache->flags & ACPI_PPTT_CACHE_ID_VALID &&
+			    cache_v1->cache_id == cache_id) {
+				cpumask_set_cpu(cpu, cpus);
+			}

Unnecessary {}  Fine to keep them if you add something else here later.

The condition being broken over multiple lines de-rails my C parsing abilities... 'Fixed'.


Thanks,

James