On 08.08.19 15:40:07, Jeremy Linton wrote:
> 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@xxxxxxx>
> Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> ---
> arch/arm64/kernel/topology.c | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index 0825c4a856e3..bad9c42ea825 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -340,17 +340,28 @@ void remove_cpu_topology(unsigned int cpu)
> }
>
> #ifdef CONFIG_ACPI
> +static int __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;
Since this is no longer bool now, better have a !!(...) or (...) != 0
here.
> +
> + 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;
Looks otherwise ok.
Reviewed-by: Robert Richter <rrichter@xxxxxxxxxxx>
