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Commit a64241ba authored by Jeremy Linton's avatar Jeremy Linton Committed by Greg Kroah-Hartman
Browse files

arm64: topology: Use PPTT to determine if PE is a thread 



Commit 98dc19902a0b2e5348e43d6a2c39a0a7d0fc639e upstream.

ACPI 6.3 adds a thread flag to represent if a CPU/PE is
actually a thread. Given that the MPIDR_MT bit may not
represent this information consistently on homogeneous machines
we should prefer the PPTT flag if its available.

Signed-off-by: default avatarJeremy Linton <jeremy.linton@arm.com>
Reviewed-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Reviewed-by: default avatarRobert Richter <rrichter@marvell.com>
[will: made acpi_cpu_is_threaded() return 'bool']
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarJohn Garry <john.garry@huawei.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent b098a4cd

arch/arm64/kernel/topology.c

+15 −4
Original line number Diff line number Diff line
@@ -340,17 +340,28 @@ void remove_cpu_topology(unsigned int cpu) 
}



#ifdef CONFIG_ACPI

static bool __init acpi_cpu_is_threaded(int cpu)

{

	int is_threaded = acpi_pptt_cpu_is_thread(cpu);



	/*

	 * if the PPTT doesn't have thread information, assume a homogeneous

	 * machine and return the current CPU's thread state.

	 */

	if (is_threaded < 0)

		is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;



	return !!is_threaded;

}



/*

 * Propagate the topology information of the processor_topology_node tree to the

 * cpu_topology array.

 */

static int __init parse_acpi_topology(void)

{

	bool is_threaded;

	int cpu, topology_id;



	is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;



	for_each_possible_cpu(cpu) {

		int i, cache_id;
@@ -358,7 +369,7 @@ static int __init parse_acpi_topology(void) 
		if (topology_id < 0)

			return topology_id;



		if (is_threaded) {

		if (acpi_cpu_is_threaded(cpu)) {

			cpu_topology[cpu].thread_id = topology_id;

			topology_id = find_acpi_cpu_topology(cpu, 1);

			cpu_topology[cpu].core_id   = topology_id;