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Message-Id: <7e6489c0.AWoAAI2o0T8AAAAAAAAAA-ma1p4AAYKJPtkAAAAAADNVAQBpc5ot@mailjet.com>
Date: Fri, 23 Jan 2026 23:56:06 +0800
From: Rong Bao <rong.bao@...antle.top>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Mingcong Bai <jeffbai@...c.io>, Kexy Biscuit <kexybiscuit@...c.io>,
Rong Bao <rong.bao@...antle.top>, stable@...r.kernel.org, WANG Xuerui
<kernel@...0n.name>, Yuli Wang <wangyuli@...ontech.com>, Yanteng Si
<si.yanteng@...ux.dev>, Masahiro Yamada <masahiroy@...nel.org>,
Hongliang Wang <wanghongliang@...ngson.cn>, Thierry Reding
<treding@...dia.com>, Tianyang Zhang <zhangtianyang@...ngson.cn>,
loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH] loongarch: retrieve CPU package ID from PPTT when available
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 noncontiguous 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 PPTT readout is
successful. The original division logic is kept as a fallback.
Cc: stable@...r.kernel.org
Signed-off-by: Rong Bao <rong.bao@...antle.top>
---
arch/loongarch/kernel/acpi.c | 9 ++++++++-
arch/loongarch/kernel/smp.c | 2 +-
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/loongarch/kernel/acpi.c b/arch/loongarch/kernel/acpi.c
index 1367ca759468..82c7ffd4f1ac 100644
--- a/arch/loongarch/kernel/acpi.c
+++ b/arch/loongarch/kernel/acpi.c
@@ -176,7 +176,7 @@ int pptt_enabled;
int __init parse_acpi_topology(void)
{
- int cpu, topology_id;
+ int cpu, topology_id, package_id;
for_each_possible_cpu(cpu) {
topology_id = find_acpi_cpu_topology(cpu, 0);
@@ -194,6 +194,13 @@ int __init parse_acpi_topology(void)
cpu_data[cpu].core = topology_id;
}
+
+ package_id = find_acpi_cpu_topology_package(cpu);
+ if (package_id < 0) {
+ pr_warn("Invalid BIOS PPTT\n");
+ return -ENOENT;
+ }
+ cpu_data[cpu].package = package_id;
}
pptt_enabled = 1;
diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c
index 8b2fcb3fb874..409e49d4da37 100644
--- a/arch/loongarch/kernel/smp.c
+++ b/arch/loongarch/kernel/smp.c
@@ -412,7 +412,7 @@ void loongson_init_secondary(void)
numa_add_cpu(cpu);
#endif
per_cpu(cpu_state, cpu) = CPU_ONLINE;
- cpu_data[cpu].package =
+ cpu_data[cpu].package = pptt_enabled ? 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;
--
2.52.0
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