Re: [PATCH 02/49] x86/cpu: Describe hybrid CPUs in cpuinfo_x86
On Mon, Feb 08, 2021 at 11:10:18AM -0800, Luck, Tony wrote:
> > +u32 x86_read_hybrid_type(void)
> > +{
> > + if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU))
> > + return cpuid_eax(0x001a);
> > +
> > + return 0;
> > +}
>
> Machine check logging will want to include this in "struct mce".
>
> But ok to pick it up with a function like you describe above.
Sure, that looks ok.
We can always lift it up into cpuinfo_x86 later, when it is needed on
the majority of machines but right now it is only a small subset of
machines which have this.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
Re: [PATCH 02/49] x86/cpu: Describe hybrid CPUs in cpuinfo_x86
On Mon, Feb 08, 2021 at 02:04:24PM -0500, Liang, Kan wrote:
> On 2/8/2021 12:56 PM, Borislav Petkov wrote:
>
> I think it's good enough for perf, but I'm not sure whether other codes need
> the CPU type information.
>
> Ricardo, do you know?
>
> Maybe we should implement a generic function as below for this?
> (Not test. Just use as an example.)
>
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index a66c1fd..679f5fe 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -2056,3 +2056,11 @@ void arch_smt_update(void)
> /* Check whether IPI broadcasting can be enabled */
> apic_smt_update();
> }
> +
> +u32 x86_read_hybrid_type(void)
> +{
> + if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU))
> + return cpuid_eax(0x001a);
> +
> + return 0;
> +}
Machine check logging will want to include this in "struct mce".
But ok to pick it up with a function like you describe above.
-Tony
Re: [PATCH 02/49] x86/cpu: Describe hybrid CPUs in cpuinfo_x86
On 2/8/2021 12:56 PM, Borislav Petkov wrote:
On Mon, Feb 08, 2021 at 07:24:59AM -0800, kan.li...@linux.intel.com wrote:
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c20a52b..1f25ac9 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -139,6 +139,16 @@ struct cpuinfo_x86 {
u32 microcode;
/* Address space bits used by the cache internally */
u8 x86_cache_bits;
+ /*
+* In hybrid processors, there is a CPU type and a native model ID. The
+* CPU type (x86_cpu_type[31:24]) describes the type of micro-
+* architecture families. The native model ID (x86_cpu_type[23:0])
+* describes a specific microarchitecture version. Combining both
+* allows to uniquely identify a CPU.
+*
+* Please note that the native model ID is not related to x86_model.
+*/
+ u32 x86_cpu_type;
Why are you adding it here instead of simply using
X86_FEATURE_HYBRID_CPU at the call site?
How many uses in this patchset?
/me searches...
Exactly one.
Just query X86_FEATURE_HYBRID_CPU at the call site and read what you
need from CPUID and use it there - no need for this.
I think it's good enough for perf, but I'm not sure whether other codes
need the CPU type information.
Ricardo, do you know?
Maybe we should implement a generic function as below for this?
(Not test. Just use as an example.)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index a66c1fd..679f5fe 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2056,3 +2056,11 @@ void arch_smt_update(void)
/* Check whether IPI broadcasting can be enabled */
apic_smt_update();
}
+
+u32 x86_read_hybrid_type(void)
+{
+ if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU))
+ return cpuid_eax(0x001a);
+
+ return 0;
+}
Thanks,
Kan
Re: [PATCH 02/49] x86/cpu: Describe hybrid CPUs in cpuinfo_x86
On Mon, Feb 08, 2021 at 07:24:59AM -0800, kan.li...@linux.intel.com wrote:
> diff --git a/arch/x86/include/asm/processor.h
> b/arch/x86/include/asm/processor.h
> index c20a52b..1f25ac9 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -139,6 +139,16 @@ struct cpuinfo_x86 {
> u32 microcode;
> /* Address space bits used by the cache internally */
> u8 x86_cache_bits;
> + /*
> + * In hybrid processors, there is a CPU type and a native model ID. The
> + * CPU type (x86_cpu_type[31:24]) describes the type of micro-
> + * architecture families. The native model ID (x86_cpu_type[23:0])
> + * describes a specific microarchitecture version. Combining both
> + * allows to uniquely identify a CPU.
> + *
> + * Please note that the native model ID is not related to x86_model.
> + */
> + u32 x86_cpu_type;
Why are you adding it here instead of simply using
X86_FEATURE_HYBRID_CPU at the call site?
How many uses in this patchset?
/me searches...
Exactly one.
Just query X86_FEATURE_HYBRID_CPU at the call site and read what you
need from CPUID and use it there - no need for this.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
