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

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: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Robert Richter <rrichter@marvell.com>
[will: made acpi_cpu_is_threaded() return 'bool']
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Jeremy Linton 2019-08-08 15:40:07 -05:00 committed by Will Deacon
parent bbd1b70639
commit 98dc19902a
1 changed files with 15 additions and 4 deletions
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19
arch/arm64/kernel/topology.c
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@ -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;