[v1] LoongArch: Correct the calculation logic of thread_count

[PATCH] LoongArch: Correct the calculation logic of thread_count

Posted by Qiang Ma 5 days, 20 hours ago

For thread_count, the current calculation method has a maximum of 255,
which may not be sufficient in the future. Therefore, we are correcting
it now.

Reference: SMBIOS Specification, 7.5 Processor Information (Type 4)[1]

[1]: https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf

Signed-off-by: Qiang Ma <maqianga@uniontech.com>
---
 arch/loongarch/kernel/setup.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 25a87378e48e..760f5ce44384 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -56,6 +56,7 @@
 #define SMBIOS_FREQLOW_MASK		0xFF
 #define SMBIOS_CORE_PACKAGE_OFFSET	0x23
 #define SMBIOS_THREAD_PACKAGE_OFFSET	0x25
+#define SMBIOS_THREAD_PACKAGE_2_OFFSET	0x2E
 #define LOONGSON_EFI_ENABLE		(1 << 3)
 
 unsigned long fw_arg0, fw_arg1, fw_arg2;
@@ -120,13 +121,19 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
 {
 	long freq_temp = 0;
 	char *dmi_data = (char *)dm;
+	u8 thread_count;
+	u16 thread_count2;
 
 	freq_temp = ((*(dmi_data + SMBIOS_FREQHIGH_OFFSET) << 8) +
 			((*(dmi_data + SMBIOS_FREQLOW_OFFSET)) & SMBIOS_FREQLOW_MASK));
 	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_THREAD_PACKAGE_OFFSET);
+	thread_count = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
+	thread_count2 = *(u16 *)(dmi_data + SMBIOS_THREAD_PACKAGE_2_OFFSET);
+	if (thread_count != 0)
+		loongson_sysconf.cores_per_package = dm->length >= 0x30 && thread_count == 0xFF ?
+						     thread_count2 : thread_count;
 
 	pr_info("CpuClock = %llu\n", cpu_clock_freq);
 }
-- 
2.20.1

Re: [PATCH] LoongArch: Correct the calculation logic of thread_count

Posted by Qiang Ma 5 days, 13 hours ago

On Wed, Nov 26, 2025 at 10:37 AM Qiang Ma<maqianga@uniontech.com> wrote:

>   For thread_count, the current calculation method has a maximum of 255,
>   which may not be sufficient in the future. Therefore, we are correcting
>   it now.
>
>   Reference: SMBIOS Specification, 7.5 Processor Information (Type 4)[1]
>
>   [1]:https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf
>
>   Signed-off-by: Qiang Ma<maqianga@uniontech.com>
>   ---
>    arch/loongarch/kernel/setup.c | 9 ++++++++-
>    1 file changed, 8 insertions(+), 1 deletion(-)
>
>   diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
>   index 25a87378e48e..760f5ce44384 100644
>   --- a/arch/loongarch/kernel/setup.c
>   +++ b/arch/loongarch/kernel/setup.c
>   @@ -56,6 +56,7 @@
>    #define SMBIOS_FREQLOW_MASK            0xFF
>    #define SMBIOS_CORE_PACKAGE_OFFSET     0x23
>    #define SMBIOS_THREAD_PACKAGE_OFFSET   0x25
>   +#define SMBIOS_THREAD_PACKAGE_2_OFFSET 0x2E
>    #define LOONGSON_EFI_ENABLE            (1 << 3)
>
>    unsigned long fw_arg0, fw_arg1, fw_arg2;
>   @@ -120,13 +121,19 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
>    {
>           long freq_temp = 0;
>           char *dmi_data = (char *)dm;
>   +       u8 thread_count;
>   +       u16 thread_count2;
>
>           freq_temp = ((*(dmi_data + SMBIOS_FREQHIGH_OFFSET) << 8) +
>                           ((*(dmi_data + SMBIOS_FREQLOW_OFFSET)) & SMBIOS_FREQLOW_MASK));
>           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_THREAD_PACKAGE_OFFSET);
>   +       thread_count = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
>   +       thread_count2 = *(u16 *)(dmi_data + SMBIOS_THREAD_PACKAGE_2_OFFSET);
>
> You have `dm->length >= 0x30` below but the memory load already done here.
After reading thread_count2, it cannot be guaranteed that the data is valid.

'dm->length >= 0x30' can detect that thread_count2 is an available data, 
right?


>   +       if (thread_count != 0)
>   +               loongson_sysconf.cores_per_package = dm->length >= 0x30 && thread_count == 0xFF ?
>   +                                                    thread_count2 : thread_count;
>
>           pr_info("CpuClock = %llu\n", cpu_clock_freq);
>    }
>   --
>   2.20.1

Re: [PATCH] LoongArch: Correct the calculation logic of thread_count

Posted by Hengqi Chen 5 days, 12 hours ago

On Wed, Nov 26, 2025 at 5:47 PM Qiang Ma <maqianga@uniontech.com> wrote:
>
>
> On Wed, Nov 26, 2025 at 10:37 AM Qiang Ma<maqianga@uniontech.com> wrote:
>
> >   For thread_count, the current calculation method has a maximum of 255,
> >   which may not be sufficient in the future. Therefore, we are correcting
> >   it now.
> >
> >   Reference: SMBIOS Specification, 7.5 Processor Information (Type 4)[1]
> >
> >   [1]:https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf
> >
> >   Signed-off-by: Qiang Ma<maqianga@uniontech.com>
> >   ---
> >    arch/loongarch/kernel/setup.c | 9 ++++++++-
> >    1 file changed, 8 insertions(+), 1 deletion(-)
> >
> >   diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> >   index 25a87378e48e..760f5ce44384 100644
> >   --- a/arch/loongarch/kernel/setup.c
> >   +++ b/arch/loongarch/kernel/setup.c
> >   @@ -56,6 +56,7 @@
> >    #define SMBIOS_FREQLOW_MASK            0xFF
> >    #define SMBIOS_CORE_PACKAGE_OFFSET     0x23
> >    #define SMBIOS_THREAD_PACKAGE_OFFSET   0x25
> >   +#define SMBIOS_THREAD_PACKAGE_2_OFFSET 0x2E
> >    #define LOONGSON_EFI_ENABLE            (1 << 3)
> >
> >    unsigned long fw_arg0, fw_arg1, fw_arg2;
> >   @@ -120,13 +121,19 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
> >    {
> >           long freq_temp = 0;
> >           char *dmi_data = (char *)dm;
> >   +       u8 thread_count;
> >   +       u16 thread_count2;
> >
> >           freq_temp = ((*(dmi_data + SMBIOS_FREQHIGH_OFFSET) << 8) +
> >                           ((*(dmi_data + SMBIOS_FREQLOW_OFFSET)) & SMBIOS_FREQLOW_MASK));
> >           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_THREAD_PACKAGE_OFFSET);
> >   +       thread_count = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
> >   +       thread_count2 = *(u16 *)(dmi_data + SMBIOS_THREAD_PACKAGE_2_OFFSET);
> >
> > You have `dm->length >= 0x30` below but the memory load already done here.
> After reading thread_count2, it cannot be guaranteed that the data is valid.
>
> 'dm->length >= 0x30' can detect that thread_count2 is an available data,
> right?
>

I mean you should perform the check before doing memory load.

>
> >   +       if (thread_count != 0)
> >   +               loongson_sysconf.cores_per_package = dm->length >= 0x30 && thread_count == 0xFF ?
> >   +                                                    thread_count2 : thread_count;
> >
> >           pr_info("CpuClock = %llu\n", cpu_clock_freq);
> >    }
> >   --
> >   2.20.1

Re: [PATCH] LoongArch: Correct the calculation logic of thread_count

Posted by Qiang Ma 5 days, 12 hours ago

在 2025/11/26 18:06, Hengqi Chen 写道:
> On Wed, Nov 26, 2025 at 5:47 PM Qiang Ma <maqianga@uniontech.com> wrote:
>>
>> On Wed, Nov 26, 2025 at 10:37 AM Qiang Ma<maqianga@uniontech.com> wrote:
>>
>>>    For thread_count, the current calculation method has a maximum of 255,
>>>    which may not be sufficient in the future. Therefore, we are correcting
>>>    it now.
>>>
>>>    Reference: SMBIOS Specification, 7.5 Processor Information (Type 4)[1]
>>>
>>>    [1]:https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf
>>>
>>>    Signed-off-by: Qiang Ma<maqianga@uniontech.com>
>>>    ---
>>>     arch/loongarch/kernel/setup.c | 9 ++++++++-
>>>     1 file changed, 8 insertions(+), 1 deletion(-)
>>>
>>>    diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
>>>    index 25a87378e48e..760f5ce44384 100644
>>>    --- a/arch/loongarch/kernel/setup.c
>>>    +++ b/arch/loongarch/kernel/setup.c
>>>    @@ -56,6 +56,7 @@
>>>     #define SMBIOS_FREQLOW_MASK            0xFF
>>>     #define SMBIOS_CORE_PACKAGE_OFFSET     0x23
>>>     #define SMBIOS_THREAD_PACKAGE_OFFSET   0x25
>>>    +#define SMBIOS_THREAD_PACKAGE_2_OFFSET 0x2E
>>>     #define LOONGSON_EFI_ENABLE            (1 << 3)
>>>
>>>     unsigned long fw_arg0, fw_arg1, fw_arg2;
>>>    @@ -120,13 +121,19 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
>>>     {
>>>            long freq_temp = 0;
>>>            char *dmi_data = (char *)dm;
>>>    +       u8 thread_count;
>>>    +       u16 thread_count2;
>>>
>>>            freq_temp = ((*(dmi_data + SMBIOS_FREQHIGH_OFFSET) << 8) +
>>>                            ((*(dmi_data + SMBIOS_FREQLOW_OFFSET)) & SMBIOS_FREQLOW_MASK));
>>>            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_THREAD_PACKAGE_OFFSET);
>>>    +       thread_count = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
>>>    +       thread_count2 = *(u16 *)(dmi_data + SMBIOS_THREAD_PACKAGE_2_OFFSET);
>>>
>>> You have `dm->length >= 0x30` below but the memory load already done here.
>> After reading thread_count2, it cannot be guaranteed that the data is valid.
>>
>> 'dm->length >= 0x30' can detect that thread_count2 is an available data,
>> right?
>>
> I mean you should perform the check before doing memory load.
It doesn't matter whether it's before or after.

Anyway, here it's just reading. Before it's actually used later,
it will check this length.
>>>    +       if (thread_count != 0)
>>>    +               loongson_sysconf.cores_per_package = dm->length >= 0x30 && thread_count == 0xFF ?
>>>    +                                                    thread_count2 : thread_count;
>>>
>>>            pr_info("CpuClock = %llu\n", cpu_clock_freq);
>>>     }
>>>    --
>>>    2.20.1

Re: [PATCH] LoongArch: Correct the calculation logic of thread_count

Posted by Hengqi Chen 5 days, 17 hours ago

On Wed, Nov 26, 2025 at 10:37 AM Qiang Ma <maqianga@uniontech.com> wrote:
>
> For thread_count, the current calculation method has a maximum of 255,
> which may not be sufficient in the future. Therefore, we are correcting
> it now.
>
> Reference: SMBIOS Specification, 7.5 Processor Information (Type 4)[1]
>
> [1]: https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf
>
> Signed-off-by: Qiang Ma <maqianga@uniontech.com>
> ---
>  arch/loongarch/kernel/setup.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> index 25a87378e48e..760f5ce44384 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -56,6 +56,7 @@
>  #define SMBIOS_FREQLOW_MASK            0xFF
>  #define SMBIOS_CORE_PACKAGE_OFFSET     0x23
>  #define SMBIOS_THREAD_PACKAGE_OFFSET   0x25
> +#define SMBIOS_THREAD_PACKAGE_2_OFFSET 0x2E
>  #define LOONGSON_EFI_ENABLE            (1 << 3)
>
>  unsigned long fw_arg0, fw_arg1, fw_arg2;
> @@ -120,13 +121,19 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
>  {
>         long freq_temp = 0;
>         char *dmi_data = (char *)dm;
> +       u8 thread_count;
> +       u16 thread_count2;
>
>         freq_temp = ((*(dmi_data + SMBIOS_FREQHIGH_OFFSET) << 8) +
>                         ((*(dmi_data + SMBIOS_FREQLOW_OFFSET)) & SMBIOS_FREQLOW_MASK));
>         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_THREAD_PACKAGE_OFFSET);
> +       thread_count = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
> +       thread_count2 = *(u16 *)(dmi_data + SMBIOS_THREAD_PACKAGE_2_OFFSET);

You have `dm->length >= 0x30` below but the memory load already done here.

> +       if (thread_count != 0)
> +               loongson_sysconf.cores_per_package = dm->length >= 0x30 && thread_count == 0xFF ?
> +                                                    thread_count2 : thread_count;
>
>         pr_info("CpuClock = %llu\n", cpu_clock_freq);
>  }
> --
> 2.20.1
>
>

Re: [PATCH] LoongArch: Correct the calculation logic of thread_count

Posted by Huacai Chen 5 days, 18 hours ago

Hi, Qiang,

On Wed, Nov 26, 2025 at 10:37 AM Qiang Ma <maqianga@uniontech.com> wrote:
>
> For thread_count, the current calculation method has a maximum of 255,
> which may not be sufficient in the future. Therefore, we are correcting
> it now.
I think you should contact the Loongson BIOS team to confirm they will do so.

And we can hardly meet the case that one socket contains more than 256
cores (this is different from the case MAX_CPUS > 256)

Huacai

>
> Reference: SMBIOS Specification, 7.5 Processor Information (Type 4)[1]
>
> [1]: https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf
>
> Signed-off-by: Qiang Ma <maqianga@uniontech.com>
> ---
>  arch/loongarch/kernel/setup.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> index 25a87378e48e..760f5ce44384 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -56,6 +56,7 @@
>  #define SMBIOS_FREQLOW_MASK            0xFF
>  #define SMBIOS_CORE_PACKAGE_OFFSET     0x23
>  #define SMBIOS_THREAD_PACKAGE_OFFSET   0x25
> +#define SMBIOS_THREAD_PACKAGE_2_OFFSET 0x2E
>  #define LOONGSON_EFI_ENABLE            (1 << 3)
>
>  unsigned long fw_arg0, fw_arg1, fw_arg2;
> @@ -120,13 +121,19 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
>  {
>         long freq_temp = 0;
>         char *dmi_data = (char *)dm;
> +       u8 thread_count;
> +       u16 thread_count2;
>
>         freq_temp = ((*(dmi_data + SMBIOS_FREQHIGH_OFFSET) << 8) +
>                         ((*(dmi_data + SMBIOS_FREQLOW_OFFSET)) & SMBIOS_FREQLOW_MASK));
>         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_THREAD_PACKAGE_OFFSET);
> +       thread_count = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
> +       thread_count2 = *(u16 *)(dmi_data + SMBIOS_THREAD_PACKAGE_2_OFFSET);
> +       if (thread_count != 0)
> +               loongson_sysconf.cores_per_package = dm->length >= 0x30 && thread_count == 0xFF ?
> +                                                    thread_count2 : thread_count;
>
>         pr_info("CpuClock = %llu\n", cpu_clock_freq);
>  }
> --
> 2.20.1
>

Re: [PATCH] LoongArch: Correct the calculation logic of thread_count

Posted by Qiang Ma 5 days, 14 hours ago

在 2025/11/26 12:49, Huacai Chen 写道:
> Hi, Qiang,
>
> On Wed, Nov 26, 2025 at 10:37 AM Qiang Ma <maqianga@uniontech.com> wrote:
>> For thread_count, the current calculation method has a maximum of 255,
>> which may not be sufficient in the future. Therefore, we are correcting
>> it now.
> I think you should contact the Loongson BIOS team to confirm they will do so.

I contacted Li Chao from the Loongson BIOS team and had a brief 
communication.

bios will do this when it exceeds 256.

>
> And we can hardly meet the case that one socket contains more than 256
> cores (this is different from the case MAX_CPUS > 256)
According to Li Chao, the 256 logic core on a single chip should arrive 
in the next generation.
> Huacai
>
>> Reference: SMBIOS Specification, 7.5 Processor Information (Type 4)[1]
>>
>> [1]: https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf
>>
>> Signed-off-by: Qiang Ma <maqianga@uniontech.com>
>> ---
>>   arch/loongarch/kernel/setup.c | 9 ++++++++-
>>   1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
>> index 25a87378e48e..760f5ce44384 100644
>> --- a/arch/loongarch/kernel/setup.c
>> +++ b/arch/loongarch/kernel/setup.c
>> @@ -56,6 +56,7 @@
>>   #define SMBIOS_FREQLOW_MASK            0xFF
>>   #define SMBIOS_CORE_PACKAGE_OFFSET     0x23
>>   #define SMBIOS_THREAD_PACKAGE_OFFSET   0x25
>> +#define SMBIOS_THREAD_PACKAGE_2_OFFSET 0x2E
>>   #define LOONGSON_EFI_ENABLE            (1 << 3)
>>
>>   unsigned long fw_arg0, fw_arg1, fw_arg2;
>> @@ -120,13 +121,19 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
>>   {
>>          long freq_temp = 0;
>>          char *dmi_data = (char *)dm;
>> +       u8 thread_count;
>> +       u16 thread_count2;
>>
>>          freq_temp = ((*(dmi_data + SMBIOS_FREQHIGH_OFFSET) << 8) +
>>                          ((*(dmi_data + SMBIOS_FREQLOW_OFFSET)) & SMBIOS_FREQLOW_MASK));
>>          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_THREAD_PACKAGE_OFFSET);
>> +       thread_count = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
>> +       thread_count2 = *(u16 *)(dmi_data + SMBIOS_THREAD_PACKAGE_2_OFFSET);
>> +       if (thread_count != 0)
>> +               loongson_sysconf.cores_per_package = dm->length >= 0x30 && thread_count == 0xFF ?
>> +                                                    thread_count2 : thread_count;
>>
>>          pr_info("CpuClock = %llu\n", cpu_clock_freq);
>>   }
>> --
>> 2.20.1
>>