linux-kernel - [PATCH] LoongArch: Get correct cores_per

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Message-ID: <20241018035920.1059661-1-chenhuacai@loongson.cn>
Date: Fri, 18 Oct 2024 11:59:20 +0800
From: Huacai Chen <chenhuacai@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: loongarch@...ts.linux.dev,
	Xuefeng Li <lixuefeng@...ngson.cn>,
	Guo Ren <guoren@...nel.org>,
	Xuerui Wang <kernel@...0n.name>,
	Jiaxun Yang <jiaxun.yang@...goat.com>,
	linux-kernel@...r.kernel.org,
	loongson-kernel@...ts.loongnix.cn,
	Huacai Chen <chenhuacai@...ngson.cn>,
	stable@...r.kernel.org,
	Chao Li <lichao@...ngson.cn>
Subject: [PATCH] LoongArch: Get correct cores_per_package for SMT systems

In loongson_sysconf, The "core" of cores_per_node and cores_per_package
stands for a logical core, which means in a SMT system it stands for a
thread indeed. This information is gotten from SMBIOS Type4 Structure,
so in order to get a correct cores_per_package for both SMT and non-SMT
systems in parse_cpu_table() we should use SMBIOS_THREAD_PACKAGE_OFFSET
instead of SMBIOS_CORE_PACKAGE_OFFSET.

Cc: stable@...r.kernel.org
Reported-by: Chao Li <lichao@...ngson.cn>
Tested-by: Chao Li <lichao@...ngson.cn>
Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 arch/loongarch/kernel/setup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 00e307203ddb..cbd3c09a93c1 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -55,6 +55,7 @@
 #define SMBIOS_FREQHIGH_OFFSET		0x17
 #define SMBIOS_FREQLOW_MASK		0xFF
 #define SMBIOS_CORE_PACKAGE_OFFSET	0x23
+#define SMBIOS_THREAD_PACKAGE_OFFSET	0x25
 #define LOONGSON_EFI_ENABLE		(1 << 3)
 
 unsigned long fw_arg0, fw_arg1, fw_arg2;
@@ -125,7 +126,7 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
 	cpu_clock_freq = freq_temp * 1000000;
 
 	loongson_sysconf.cpuname = (void *)dmi_string_parse(dm, dmi_data[16]);
-	loongson_sysconf.cores_per_package = *(dmi_data + SMBIOS_CORE_PACKAGE_OFFSET);
+	loongson_sysconf.cores_per_package = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
 
 	pr_info("CpuClock = %llu\n", cpu_clock_freq);
 }
-- 
2.43.5

diff --git a/arch/loongarch/include/asm/bootinfo.h b/arch/loongarch/include/asm/bootinfo.h
index 6d5846dd075c..7657e016233f 100644
--- a/arch/loongarch/include/asm/bootinfo.h
+++ b/arch/loongarch/include/asm/bootinfo.h
@@ -26,6 +26,10 @@ struct loongson_board_info {
 
 #define NR_WORDS DIV_ROUND_UP(NR_CPUS, BITS_PER_LONG)
 
+/*
+ * The "core" of cores_per_node and cores_per_package stands for a
+ * logical core, which means in a SMT system it stands for a thread.
+ */
 struct loongson_system_configuration {
 	int nr_cpus;
 	int nr_nodes;