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Date:   Wed, 20 Feb 2019 10:59:05 +0800
From:   Like Xu <like.xu@...ux.intel.com>
To:     Len Brown <lenb@...nel.org>, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, Len Brown <len.brown@...el.com>,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH 03/11] x86 topology: Add CPUID.1F multi-die/package
 support

On 2019/2/19 11:40, Len Brown wrote:
> From: Len Brown <len.brown@...el.com>
> 
> Some new systems have multiple software-visible die within each package.
> The new CPUID.1F leaf can enumerate this multi-die/package topology.
> 
> CPUID.1F a super-set of the CPUID.B "Extended Toplogy Leaf",
> and a common updated routine can parse either leaf.
> 
> Legacy systems without CPUID.1F, and systems without multi-die/package
> hardware, will see no functional change from this patch series.
> 
> Multi-die/package systems will use CPUID.B before this patch,
> and CPUID.1F after this patch.  In the CPUID.B case, all die appear
> (incorrectly) to software as individual packages.  In the CPUID.1F case,
> the package id's reflect reality, and die_id's become meaningful.
> 
> Subsequent patches in this series update the kernel to be multi-die aware.
> In particular, some software needs to know the difference between
> a die-scope MSR and a package-scope MSR.
> 
> Signed-off-by: Len Brown <len.brown@...el.com>
> Cc: linux-doc@...r.kernel.org
> Signed-off-by: Len Brown <len.brown@...el.com>
> ---
>   Documentation/x86/topology.txt   |  4 ++
>   arch/x86/include/asm/processor.h |  4 +-
>   arch/x86/kernel/cpu/topology.c   | 82 ++++++++++++++++++++++++--------
>   arch/x86/kernel/smpboot.c        |  4 +-
>   4 files changed, 73 insertions(+), 21 deletions(-)
> 
> diff --git a/Documentation/x86/topology.txt b/Documentation/x86/topology.txt
> index 06b3cdbc4048..8107b6cfc9ea 100644
> --- a/Documentation/x86/topology.txt
> +++ b/Documentation/x86/topology.txt
> @@ -46,6 +46,10 @@ The topology of a system is described in the units of:
>   
>       The number of cores in a package. This information is retrieved via CPUID.
>   
> +  - cpuinfo_x86.x86_max_dies:
> +
> +    The number of dies in a package. This information is retrieved via CPUID.
> +
>     - cpuinfo_x86.phys_proc_id:
>   
>       The physical ID of the package. This information is retrieved via CPUID
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 33051436c864..f2856fe03715 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -105,7 +105,8 @@ struct cpuinfo_x86 {
>   	int			x86_power;
>   	unsigned long		loops_per_jiffy;
>   	/* cpuid returned max cores value: */
> -	u16			 x86_max_cores;
> +	u16			x86_max_cores;
> +	u16			x86_max_dies;
>   	u16			apicid;
>   	u16			initial_apicid;
>   	u16			x86_clflush_size;
> @@ -117,6 +118,7 @@ struct cpuinfo_x86 {
>   	u16			logical_proc_id;
>   	/* Core id: */
>   	u16			cpu_core_id;
> +	u16			cpu_die_id;
>   	/* Index into per_cpu list: */
>   	u16			cpu_index;
>   	u32			microcode;
> diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
> index 8f6c784141d1..6dce6ee77849 100644
> --- a/arch/x86/kernel/cpu/topology.c
> +++ b/arch/x86/kernel/cpu/topology.c
> @@ -15,33 +15,61 @@
>   /* leaf 0xb SMT level */
>   #define SMT_LEVEL	0
>   
> -/* leaf 0xb sub-leaf types */
> +/* extended topology sub-leaf types */
>   #define INVALID_TYPE	0
>   #define SMT_TYPE	1
>   #define CORE_TYPE	2
> +#define DIE_TYPE	5

This patch set is going to export die topology via sysfs
while the extended topology sub-leaf type could be one of followings:
SMT/Core/Module/Tile/Die according to CPUID.1F from SDM.

Why not choose to export module/tile topology as well?

>   
>   #define LEAFB_SUBTYPE(ecx)		(((ecx) >> 8) & 0xff)
>   #define BITS_SHIFT_NEXT_LEVEL(eax)	((eax) & 0x1f)
>   #define LEVEL_MAX_SIBLINGS(ebx)		((ebx) & 0xffff)
>   
> -int detect_extended_topology_early(struct cpuinfo_x86 *c)
> -{
>   #ifdef CONFIG_SMP
> +/*
> + * Check if given CPUID extended toplogy "leaf" is implemented
> + */
> +static int check_extended_topology_leaf(int leaf)
> +{
>   	unsigned int eax, ebx, ecx, edx;
>   
> -	if (c->cpuid_level < 0xb)
> +	cpuid_count(leaf, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
> +
> +	if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
>   		return -1;
>   
> -	cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
> +	return 0;
> +}
> +/*
> + * Return best CPUID Extended Toplogy Leaf supported
> + */
> +static int detect_extended_topology_leaf(struct cpuinfo_x86 *c)
> +{
> +	if (c->cpuid_level >= 0x1f)
> +		if (check_extended_topology_leaf(0x1f) == 0)
> +			return 0x1f;
>   
> -	/*
> -	 * check if the cpuid leaf 0xb is actually implemented.
> -	 */
> -	if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
> +	if (c->cpuid_level >= 0xb)
> +		if (check_extended_topology_leaf(0xb) == 0)
> +			return 0xb;
> +
> +	return -1;
> +}
> +#endif
> +
> +int detect_extended_topology_early(struct cpuinfo_x86 *c)
> +{
> +#ifdef CONFIG_SMP
> +	unsigned int eax, ebx, ecx, edx;
> +	int leaf;
> +
> +	leaf = detect_extended_topology_leaf(c);
> +	if (leaf < 0)
>   		return -1;
>   
>   	set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);
>   
> +	cpuid_count(leaf, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
>   	/*
>   	 * initial apic id, which also represents 32-bit extended x2apic id.
>   	 */
> @@ -52,7 +80,7 @@ int detect_extended_topology_early(struct cpuinfo_x86 *c)
>   }
>   
>   /*
> - * Check for extended topology enumeration cpuid leaf 0xb and if it
> + * Check for extended topology enumeration cpuid leaf, and if it
>    * exists, use it for populating initial_apicid and cpu topology
>    * detection.
>    */
> @@ -60,46 +88,62 @@ int detect_extended_topology(struct cpuinfo_x86 *c)
>   {
>   #ifdef CONFIG_SMP
>   	unsigned int eax, ebx, ecx, edx, sub_index;
> -	unsigned int ht_mask_width, core_plus_mask_width;
> +	unsigned int ht_mask_width, core_plus_mask_width, die_plus_mask_width;
>   	unsigned int core_select_mask, core_level_siblings;
> +	unsigned int die_select_mask, die_level_siblings;
> +	int leaf;
>   
> -	if (detect_extended_topology_early(c) < 0)
> +	leaf = detect_extended_topology_leaf(c);
> +	if (leaf  < 0)
>   		return -1;
>   
>   	/*
>   	 * Populate HT related information from sub-leaf level 0.
>   	 */
> -	cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
> +	cpuid_count(leaf, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
> +	c->initial_apicid = edx;
>   	core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
>   	core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
> +	die_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
> +	die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
>   
>   	sub_index = 1;
>   	do {
> -		cpuid_count(0xb, sub_index, &eax, &ebx, &ecx, &edx);
> +		cpuid_count(leaf, sub_index, &eax, &ebx, &ecx, &edx);
>   
>   		/*
>   		 * Check for the Core type in the implemented sub leaves.
>   		 */
>   		if (LEAFB_SUBTYPE(ecx) == CORE_TYPE) {
>   			core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
> +			die_level_siblings = core_level_siblings;
>   			core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
> -			break;
> +		}
> +		if (LEAFB_SUBTYPE(ecx) == DIE_TYPE) {
> +			die_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
> +			die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
>   		}
>   
>   		sub_index++;
>   	} while (LEAFB_SUBTYPE(ecx) != INVALID_TYPE);
>   
>   	core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width;
> -
> -	c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid, ht_mask_width)
> -						 & core_select_mask;
> -	c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, core_plus_mask_width);
> +	die_select_mask = (~(-1 << die_plus_mask_width)) >>
> +				core_plus_mask_width;
> +
> +	c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid,
> +				ht_mask_width) & core_select_mask;
> +	c->cpu_die_id = apic->phys_pkg_id(c->initial_apicid,
> +				core_plus_mask_width) & die_select_mask;
> +	c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid,
> +				die_plus_mask_width);
>   	/*
>   	 * Reinit the apicid, now that we have extended initial_apicid.
>   	 */
>   	c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
>   
>   	c->x86_max_cores = (core_level_siblings / smp_num_siblings);
> +	c->x86_max_dies = (die_level_siblings / core_level_siblings);
>   #endif
>   	return 0;
>   }
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index ccd1f2a8e557..4250a87f57db 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -393,6 +393,7 @@ static bool match_smt(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
>   		int cpu1 = c->cpu_index, cpu2 = o->cpu_index;
>   
>   		if (c->phys_proc_id == o->phys_proc_id &&
> +		    c->cpu_die_id == o->cpu_die_id &&
>   		    per_cpu(cpu_llc_id, cpu1) == per_cpu(cpu_llc_id, cpu2)) {
>   			if (c->cpu_core_id == o->cpu_core_id)
>   				return topology_sane(c, o, "smt");
> @@ -404,6 +405,7 @@ static bool match_smt(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
>   		}
>   
>   	} else if (c->phys_proc_id == o->phys_proc_id &&
> +		   c->cpu_die_id == o->cpu_die_id &&
>   		   c->cpu_core_id == o->cpu_core_id) {
>   		return topology_sane(c, o, "smt");
>   	}
> @@ -461,7 +463,7 @@ static bool match_llc(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
>    */
>   static bool match_die(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
>   {
> -	if (c->phys_proc_id == o->phys_proc_id)
> +	if (c->cpu_die_id == o->cpu_die_id)
>   		return true;
>   	return false;
>   }
> 

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