[PATCH for-stable-5.3 2/2] arm64: topology: Use PPTT to determine if PE is a thread
From: John Garry <hidden>
Date: 2019-10-14 11:59:19
Also in:
linux-acpi, lkml, stable
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
From: Jeremy Linton <redacted> 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: Jeremy Linton <redacted> Reviewed-by: Sudeep Holla <redacted> Reviewed-by: Robert Richter <redacted> [will: made acpi_cpu_is_threaded() return 'bool'] Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: John Garry <redacted> --- 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..6106c49f84bc 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 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;
--
2.17.1
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