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LoongArch: Retrieve CPU package ID from PPTT when available

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Currently, the LoongArch CPU topology initialization code calculates
each core's package ID by dividing its physical ID by loongson_sysconf.
cores_per_package. This relies on the assumption that cores_per_package
counts in the same domain as physical IDs.

On Loongson-3B6000 (XB612B0V_1.2), cores_per_package matches the visible
core count -- 24 in this case. However, the physical IDs range from 0 to
31 in a noncontinuous fashion:

        $ cat /proc/cpuinfo | grep -i -F 'global_id'
        global_id               : 0
        global_id               : 1
        global_id               : 4
        global_id               : 5
        global_id               : 6
        global_id               : 7
        global_id               : 8
        global_id               : 9
        global_id               : 10
        global_id               : 11
        global_id               : 14
        global_id               : 15
        global_id               : 16
        global_id               : 17
        global_id               : 20
        global_id               : 21
        global_id               : 22
        global_id               : 23
        global_id               : 26
        global_id               : 27
        global_id               : 28
        global_id               : 29
        global_id               : 30
        global_id               : 31

Retrieve the exact package ID from ACPI PPTT when available, in the same
style as retrieving the core ID and thread ID in parse_acpi_topology().
Use this information in loongson_init_secondary() when the PPTT readout
is successful. The original division logic is kept as a fallback.

Meanwhile, since some existing code paths like loongson3_cpufreq expect
a continuous integer sequence of package IDs in [0, MAX_PACKAGES) when
retrieving from cpu_data[], here we also canonicalize the package ID to
be filled in parse_acpi_topology() to meet such an expectation.

Cc: stable@vger.kernel.org
Tested-by: Mingcong Bai <jeffbai@aosc.io>
Co-developed-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Rong Bao <rong.bao@csmantle.top>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Rong Bao 2026-07-23 22:27:29 +08:00 committed by Huacai Chen
parent ea68d444a6
commit 4e8f58620f
2 changed files with 28 additions and 3 deletions
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27
arch/loongarch/kernel/acpi.c
View File

@ -201,10 +201,12 @@ static void __init acpi_process_madt(void)
}
int pptt_enabled;
static int acpi_nr_packages;
static int acpi_package_ids[MAX_PACKAGES];
int __init parse_acpi_topology(void)
{
int cpu, topology_id;
int i, cpu, topology_id;
for_each_possible_cpu(cpu) {
topology_id = find_acpi_cpu_topology(cpu, 0);
@ -222,6 +224,29 @@ int __init parse_acpi_topology(void)
cpu_data[cpu].core = topology_id;
}
topology_id = find_acpi_cpu_topology_package(cpu);
if (topology_id < 0) {
pr_warn("Invalid BIOS PPTT\n");
return -ENOENT;
}
for (i = 0; i < acpi_nr_packages; i++)
if (acpi_package_ids[i] == topology_id)
break;
if (i == acpi_nr_packages)
acpi_package_ids[acpi_nr_packages++] = topology_id;
cpu_data[cpu].package = topology_id;
}
for_each_possible_cpu(cpu) {
for (i = 0; i < acpi_nr_packages; i++)
if (cpu_data[cpu].package == acpi_package_ids[i]) {
cpu_data[cpu].package = i; /* Canonicalize */
break;
}
}
pptt_enabled = 1;

4
arch/loongarch/kernel/smp.c
View File

@ -426,10 +426,10 @@ void loongson_init_secondary(void)
numa_add_cpu(cpu);
#endif
per_cpu(cpu_state, cpu) = CPU_ONLINE;
cpu_data[cpu].package =
cpu_logical_map(cpu) / loongson_sysconf.cores_per_package;
cpu_data[cpu].core = pptt_enabled ? cpu_data[cpu].core :
cpu_logical_map(cpu) % loongson_sysconf.cores_per_package;
cpu_data[cpu].package = pptt_enabled ? cpu_data[cpu].package :
cpu_logical_map(cpu) / loongson_sysconf.cores_per_package;
cpu_data[cpu].global_id = cpu_logical_map(cpu);
}