* [PATCH v2 0/3] x86/topology: Add support for Low Power cpu_type
@ 2026-07-21 15:45 Vishal Badole
2026-07-21 15:45 ` [PATCH v2 1/3] x86/topo: Map vendor CPU types to generic Linux such types Vishal Badole
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Vishal Badole @ 2026-07-21 15:45 UTC (permalink / raw)
To: tglx, mingo, bp, dave.hansen, x86, hpa, rafael, lenb
Cc: linux-kernel, linux-acpi, peterz, tony.luck, chang.seok.bae,
wei.w.wang, Vishal Badole
This series extends the x86 topology cpu_type classification to support
a Low Power core type, in addition to the existing Performance and
Efficiency types.
AMD heterogeneous parts report the core type via CPUID Fn0x80000026
EBX[31:28] (Extended CPU Topology, Core Type). Value 2 identifies a
low-power core. Distinguishing it from a regular efficiency core
matters for:
- user space exposure via /sys/kernel/debug/x86/topo/cpus/*, which
today reports cpu_type "unknown" for low-power cores
- amd_get_boost_ratio_numerator(): on every
X86_FEATURE_AMD_HTR_CORES-capable AMD/Hygon part, low-power cores
must scale by amd_get_highest_perf() rather than the fixed
CPPC_HIGHEST_PERF_PERFORMANCE ceiling, matching the existing
efficiency-core path
During the v1 review, Sashiko flagged a pre-existing issue in how
x86_match_cpu() handles vendor CPU types. v2 therefore starts with a
preparatory patch from Borislav that switches matching to the kernel's
vendor-agnostic TOPO_CPU_TYPE_* enum; see its commit message for
details. The Low Power support is then added on top.
The series is structured as:
1/3 Map the vendor (Intel/AMD) hardware core type to the
vendor-agnostic enum x86_topology_cpu_type at enumeration and
match against it. See the patch's commit message for details.
2/3 Replace the bare 0/1 in get_topology_cpu_type() with named
enum amd_cpu_type constants, mirroring the existing Intel side.
No functional change.
3/3 Add TOPO_CPU_TYPE_LOW_POWER, wire it through
get_topology_cpu_type(), get_topology_cpu_type_name() and the
switch in amd_get_boost_ratio_numerator() so allmodconfig builds
cleanly under -Werror=switch.
Changes in v2:
- New preparatory patch 1/3 from Borislav Petkov switching
x86_match_cpu() to the vendor-agnostic TOPO_CPU_TYPE_* enum; see
its commit message for the rationale. (Thomas Gleixner,
Borislav Petkov)
- No change to the Low Power translation logic itself; patches 2/3
and 3/3 are the v1 patches rebased on top of the new 1/3.
v1: https://lore.kernel.org/all/20260629094349.533301-1-Vishal.Badole@amd.com
Borislav Petkov (AMD) (1):
x86/topo: Map vendor CPU types to generic Linux such types
Vishal Badole (2):
x86/topology: Name the AMD core-type values
x86/topology: Add TOPO_CPU_TYPE_LOW_POWER
arch/x86/include/asm/processor.h | 19 +++++++++++++----
arch/x86/include/asm/topology.h | 9 ++++----
arch/x86/kernel/acpi/cppc.c | 7 ++++---
arch/x86/kernel/cpu/match.c | 30 +--------------------------
arch/x86/kernel/cpu/topology.h | 1 +
arch/x86/kernel/cpu/topology_amd.c | 6 ++++--
arch/x86/kernel/cpu/topology_common.c | 15 ++++++++++----
7 files changed, 40 insertions(+), 47 deletions(-)
--
2.34.1
^ permalink raw reply [flat|nested] 7+ messages in thread* [PATCH v2 1/3] x86/topo: Map vendor CPU types to generic Linux such types 2026-07-21 15:45 [PATCH v2 0/3] x86/topology: Add support for Low Power cpu_type Vishal Badole @ 2026-07-21 15:45 ` Vishal Badole 2026-07-25 1:39 ` [tip: x86/cpu] " tip-bot2 for Borislav Petkov (AMD) 2026-07-21 15:45 ` [PATCH v2 2/3] x86/topology: Name the AMD core-type values Vishal Badole 2026-07-21 15:45 ` [PATCH v2 3/3] x86/topology: Add TOPO_CPU_TYPE_LOW_POWER Vishal Badole 2 siblings, 1 reply; 7+ messages in thread From: Vishal Badole @ 2026-07-21 15:45 UTC (permalink / raw) To: tglx, mingo, bp, dave.hansen, x86, hpa, rafael, lenb Cc: linux-kernel, linux-acpi, peterz, tony.luck, chang.seok.bae, wei.w.wang, Vishal Badole From: "Borislav Petkov (AMD)" <bp@alien8.de> Sashiko reported¹ that a confusion could ensue if a vendor-specific CPU type 0 (performance) gets attempted to be used in a x86_cpu_id match table. The current logic treats 0 as the wildcard X86_CPU_TYPE_ANY and such a thing would end up matching the wrong CPUs. This is all backwards because we started using the vendor-specific CPU type number instead of using a Linux-defined, generic CPU type which is agnostic. Convert the current logic to it before users start appearing. ¹https://sashiko.dev/#/patchset/20260629094349.533301-1-Vishal.Badole%40amd.com Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Vishal Badole <Vishal.Badole@amd.com> --- arch/x86/include/asm/processor.h | 18 ++++++++++++---- arch/x86/include/asm/topology.h | 7 ------- arch/x86/kernel/acpi/cppc.c | 4 ++-- arch/x86/kernel/cpu/match.c | 30 +-------------------------- arch/x86/kernel/cpu/topology.h | 1 + arch/x86/kernel/cpu/topology_amd.c | 6 ++++-- arch/x86/kernel/cpu/topology_common.c | 8 +++++-- 7 files changed, 28 insertions(+), 46 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 87b1d4c0727e..fc0350fe8f5e 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -68,9 +68,13 @@ extern u16 __read_mostly tlb_lld_2m; extern u16 __read_mostly tlb_lld_4m; extern u16 __read_mostly tlb_lld_1g; -/* - * CPU type and hardware bug flags. Kept separately for each CPU. - */ +enum x86_topology_cpu_type { + /* X86_CPU_TYPE_ANY */ + TOPO_CPU_TYPE_ANY = 0, + TOPO_CPU_TYPE_PERFORMANCE, + TOPO_CPU_TYPE_EFFICIENCY, + TOPO_CPU_TYPE_UNKNOWN, +}; struct cpuinfo_topology { // Real APIC ID read from the local APIC @@ -104,7 +108,7 @@ struct cpuinfo_topology { // Hardware defined CPU-type union { - u32 cpu_type; + u32 hw_cpu_type; struct { // CPUID.1A.EAX[23-0] u32 intel_native_model_id :24; @@ -119,8 +123,14 @@ struct cpuinfo_topology { amd_type :4; }; }; + + // Linux vendor-agnostic CPU type + enum x86_topology_cpu_type cpu_type; }; +/* + * CPU type and hardware bug flags. Kept separately for each CPU. + */ struct cpuinfo_x86 { union { /* diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index 8fb61d2465eb..ef76ba674f1b 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -114,12 +114,6 @@ enum x86_topology_domains { TOPO_MAX_DOMAIN, }; -enum x86_topology_cpu_type { - TOPO_CPU_TYPE_PERFORMANCE, - TOPO_CPU_TYPE_EFFICIENCY, - TOPO_CPU_TYPE_UNKNOWN, -}; - struct x86_topology_system { unsigned int dom_shifts[TOPO_MAX_DOMAIN]; unsigned int dom_size[TOPO_MAX_DOMAIN]; @@ -160,7 +154,6 @@ extern unsigned int __num_nodes_per_package; struct cpuinfo_x86; const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c); -enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c); static inline unsigned int topology_max_packages(void) { diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c index be4c5e9e5ff6..b8f5dd0a8117 100644 --- a/arch/x86/kernel/acpi/cppc.c +++ b/arch/x86/kernel/acpi/cppc.c @@ -241,7 +241,6 @@ EXPORT_SYMBOL_GPL(amd_detect_prefcore); */ int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) { - enum x86_topology_cpu_type core_type = get_topology_cpu_type(&cpu_data(cpu)); bool prefcore; int ret; u32 tmp; @@ -273,8 +272,9 @@ int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) /* detect if running on heterogeneous design */ if (cpu_feature_enabled(X86_FEATURE_AMD_HTR_CORES)) { - switch (core_type) { + switch (cpu_data(cpu).topo.cpu_type) { case TOPO_CPU_TYPE_UNKNOWN: + case TOPO_CPU_TYPE_ANY: pr_warn("Undefined core type found for cpu %d\n", cpu); break; case TOPO_CPU_TYPE_PERFORMANCE: diff --git a/arch/x86/kernel/cpu/match.c b/arch/x86/kernel/cpu/match.c index 4604802692da..7ab077f0cc66 100644 --- a/arch/x86/kernel/cpu/match.c +++ b/arch/x86/kernel/cpu/match.c @@ -5,34 +5,6 @@ #include <linux/export.h> #include <linux/slab.h> -/** - * x86_match_vendor_cpu_type - helper function to match the hardware defined - * cpu-type for a single entry in the x86_cpu_id - * table. Note, this function does not match the - * generic cpu-types TOPO_CPU_TYPE_EFFICIENCY and - * TOPO_CPU_TYPE_PERFORMANCE. - * @c: Pointer to the cpuinfo_x86 structure of the CPU to match. - * @m: Pointer to the x86_cpu_id entry to match against. - * - * Return: true if the cpu-type matches, false otherwise. - */ -static bool x86_match_vendor_cpu_type(struct cpuinfo_x86 *c, const struct x86_cpu_id *m) -{ - if (m->type == X86_CPU_TYPE_ANY) - return true; - - /* Hybrid CPUs are special, they are assumed to match all cpu-types */ - if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU)) - return true; - - if (c->x86_vendor == X86_VENDOR_INTEL) - return m->type == c->topo.intel_type; - if (c->x86_vendor == X86_VENDOR_AMD) - return m->type == c->topo.amd_type; - - return false; -} - /** * x86_match_cpu - match current CPU against an array of x86_cpu_ids * @match: Pointer to array of x86_cpu_ids. Last entry terminated with @@ -81,7 +53,7 @@ const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match) continue; if (m->feature != X86_FEATURE_ANY && !cpu_has(c, m->feature)) continue; - if (!x86_match_vendor_cpu_type(c, m)) + if (m->type != X86_CPU_TYPE_ANY && c->topo.cpu_type != m->type) continue; return m; } diff --git a/arch/x86/kernel/cpu/topology.h b/arch/x86/kernel/cpu/topology.h index 37326297f80c..74e02bacd854 100644 --- a/arch/x86/kernel/cpu/topology.h +++ b/arch/x86/kernel/cpu/topology.h @@ -22,6 +22,7 @@ void topology_set_dom(struct topo_scan *tscan, enum x86_topology_domains dom, bool cpu_parse_topology_ext(struct topo_scan *tscan); void cpu_parse_topology_amd(struct topo_scan *tscan); void cpu_topology_fixup_amd(struct topo_scan *tscan); +enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c); static inline u32 topo_shift_apicid(u32 apicid, enum x86_topology_domains dom) { diff --git a/arch/x86/kernel/cpu/topology_amd.c b/arch/x86/kernel/cpu/topology_amd.c index da080d732e10..c5a6944df86a 100644 --- a/arch/x86/kernel/cpu/topology_amd.c +++ b/arch/x86/kernel/cpu/topology_amd.c @@ -177,8 +177,10 @@ static void topoext_fixup(struct topo_scan *tscan) static void parse_topology_amd(struct topo_scan *tscan) { - if (cpu_feature_enabled(X86_FEATURE_AMD_HTR_CORES)) - tscan->c->topo.cpu_type = cpuid_ebx(0x80000026); + if (cpu_feature_enabled(X86_FEATURE_AMD_HTR_CORES)) { + tscan->c->topo.hw_cpu_type = cpuid_ebx(0x80000026); + tscan->c->topo.cpu_type = get_topology_cpu_type(tscan->c); + } /* * Try to get SMT, CORE, TILE, and DIE shifts from extended diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index cf7513416b70..b9d025f3373a 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -168,8 +168,12 @@ static void parse_topology(struct topo_scan *tscan, bool early) case X86_VENDOR_INTEL: if (!IS_ENABLED(CONFIG_CPU_SUP_INTEL) || !cpu_parse_topology_ext(tscan)) parse_legacy(tscan); - if (c->cpuid_level >= 0x1a) - c->topo.cpu_type = cpuid_eax(0x1a); + + if (c->cpuid_level >= 0x1a) { + c->topo.hw_cpu_type = cpuid_eax(0x1a); + c->topo.cpu_type = get_topology_cpu_type(c); + } + break; } } -- 2.34.1 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip: x86/cpu] x86/topo: Map vendor CPU types to generic Linux such types 2026-07-21 15:45 ` [PATCH v2 1/3] x86/topo: Map vendor CPU types to generic Linux such types Vishal Badole @ 2026-07-25 1:39 ` tip-bot2 for Borislav Petkov (AMD) 0 siblings, 0 replies; 7+ messages in thread From: tip-bot2 for Borislav Petkov (AMD) @ 2026-07-25 1:39 UTC (permalink / raw) To: linux-tip-commits; +Cc: Borislav Petkov (AMD), Vishal Badole, x86, linux-kernel The following commit has been merged into the x86/cpu branch of tip: Commit-ID: 598ebce64c4cfaca54cbecdc25a7ef56ea701051 Gitweb: https://git.kernel.org/tip/598ebce64c4cfaca54cbecdc25a7ef56ea701051 Author: Borislav Petkov (AMD) <bp@alien8.de> AuthorDate: Tue, 21 Jul 2026 21:15:12 +05:30 Committer: Borislav Petkov (AMD) <bp@alien8.de> CommitterDate: Thu, 23 Jul 2026 14:23:15 -07:00 x86/topo: Map vendor CPU types to generic Linux such types Sashiko reported¹ that a confusion could ensue if a vendor-specific CPU type 0 (performance) gets attempted to be used in a x86_cpu_id match table. The current logic treats 0 as the wildcard X86_CPU_TYPE_ANY and such a thing would end up matching the wrong CPUs. This is all backwards because we started using the vendor-specific CPU type number instead of using a Linux-defined, generic CPU type which is agnostic. Convert the current logic to it before users start appearing. ¹https://sashiko.dev/#/patchset/20260629094349.533301-1-Vishal.Badole%40amd.com Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Vishal Badole <Vishal.Badole@amd.com> Link: https://patch.msgid.link/20260721154514.2506972-2-Vishal.Badole@amd.com --- arch/x86/include/asm/processor.h | 18 ++++++++++++---- arch/x86/include/asm/topology.h | 7 +------ arch/x86/kernel/acpi/cppc.c | 4 +-- arch/x86/kernel/cpu/match.c | 30 +-------------------------- arch/x86/kernel/cpu/topology.h | 1 +- arch/x86/kernel/cpu/topology_amd.c | 6 +++-- arch/x86/kernel/cpu/topology_common.c | 8 +++++-- 7 files changed, 28 insertions(+), 46 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 87b1d4c..fc0350f 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -68,9 +68,13 @@ extern u16 __read_mostly tlb_lld_2m; extern u16 __read_mostly tlb_lld_4m; extern u16 __read_mostly tlb_lld_1g; -/* - * CPU type and hardware bug flags. Kept separately for each CPU. - */ +enum x86_topology_cpu_type { + /* X86_CPU_TYPE_ANY */ + TOPO_CPU_TYPE_ANY = 0, + TOPO_CPU_TYPE_PERFORMANCE, + TOPO_CPU_TYPE_EFFICIENCY, + TOPO_CPU_TYPE_UNKNOWN, +}; struct cpuinfo_topology { // Real APIC ID read from the local APIC @@ -104,7 +108,7 @@ struct cpuinfo_topology { // Hardware defined CPU-type union { - u32 cpu_type; + u32 hw_cpu_type; struct { // CPUID.1A.EAX[23-0] u32 intel_native_model_id :24; @@ -119,8 +123,14 @@ struct cpuinfo_topology { amd_type :4; }; }; + + // Linux vendor-agnostic CPU type + enum x86_topology_cpu_type cpu_type; }; +/* + * CPU type and hardware bug flags. Kept separately for each CPU. + */ struct cpuinfo_x86 { union { /* diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index 8fb61d2..ef76ba6 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -114,12 +114,6 @@ enum x86_topology_domains { TOPO_MAX_DOMAIN, }; -enum x86_topology_cpu_type { - TOPO_CPU_TYPE_PERFORMANCE, - TOPO_CPU_TYPE_EFFICIENCY, - TOPO_CPU_TYPE_UNKNOWN, -}; - struct x86_topology_system { unsigned int dom_shifts[TOPO_MAX_DOMAIN]; unsigned int dom_size[TOPO_MAX_DOMAIN]; @@ -160,7 +154,6 @@ extern unsigned int __num_nodes_per_package; struct cpuinfo_x86; const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c); -enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c); static inline unsigned int topology_max_packages(void) { diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c index be4c5e9..b8f5dd0 100644 --- a/arch/x86/kernel/acpi/cppc.c +++ b/arch/x86/kernel/acpi/cppc.c @@ -241,7 +241,6 @@ EXPORT_SYMBOL_GPL(amd_detect_prefcore); */ int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) { - enum x86_topology_cpu_type core_type = get_topology_cpu_type(&cpu_data(cpu)); bool prefcore; int ret; u32 tmp; @@ -273,8 +272,9 @@ int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) /* detect if running on heterogeneous design */ if (cpu_feature_enabled(X86_FEATURE_AMD_HTR_CORES)) { - switch (core_type) { + switch (cpu_data(cpu).topo.cpu_type) { case TOPO_CPU_TYPE_UNKNOWN: + case TOPO_CPU_TYPE_ANY: pr_warn("Undefined core type found for cpu %d\n", cpu); break; case TOPO_CPU_TYPE_PERFORMANCE: diff --git a/arch/x86/kernel/cpu/match.c b/arch/x86/kernel/cpu/match.c index 4604802..7ab077f 100644 --- a/arch/x86/kernel/cpu/match.c +++ b/arch/x86/kernel/cpu/match.c @@ -6,34 +6,6 @@ #include <linux/slab.h> /** - * x86_match_vendor_cpu_type - helper function to match the hardware defined - * cpu-type for a single entry in the x86_cpu_id - * table. Note, this function does not match the - * generic cpu-types TOPO_CPU_TYPE_EFFICIENCY and - * TOPO_CPU_TYPE_PERFORMANCE. - * @c: Pointer to the cpuinfo_x86 structure of the CPU to match. - * @m: Pointer to the x86_cpu_id entry to match against. - * - * Return: true if the cpu-type matches, false otherwise. - */ -static bool x86_match_vendor_cpu_type(struct cpuinfo_x86 *c, const struct x86_cpu_id *m) -{ - if (m->type == X86_CPU_TYPE_ANY) - return true; - - /* Hybrid CPUs are special, they are assumed to match all cpu-types */ - if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU)) - return true; - - if (c->x86_vendor == X86_VENDOR_INTEL) - return m->type == c->topo.intel_type; - if (c->x86_vendor == X86_VENDOR_AMD) - return m->type == c->topo.amd_type; - - return false; -} - -/** * x86_match_cpu - match current CPU against an array of x86_cpu_ids * @match: Pointer to array of x86_cpu_ids. Last entry terminated with * {}. @@ -81,7 +53,7 @@ const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match) continue; if (m->feature != X86_FEATURE_ANY && !cpu_has(c, m->feature)) continue; - if (!x86_match_vendor_cpu_type(c, m)) + if (m->type != X86_CPU_TYPE_ANY && c->topo.cpu_type != m->type) continue; return m; } diff --git a/arch/x86/kernel/cpu/topology.h b/arch/x86/kernel/cpu/topology.h index 3732629..74e02ba 100644 --- a/arch/x86/kernel/cpu/topology.h +++ b/arch/x86/kernel/cpu/topology.h @@ -22,6 +22,7 @@ void topology_set_dom(struct topo_scan *tscan, enum x86_topology_domains dom, bool cpu_parse_topology_ext(struct topo_scan *tscan); void cpu_parse_topology_amd(struct topo_scan *tscan); void cpu_topology_fixup_amd(struct topo_scan *tscan); +enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c); static inline u32 topo_shift_apicid(u32 apicid, enum x86_topology_domains dom) { diff --git a/arch/x86/kernel/cpu/topology_amd.c b/arch/x86/kernel/cpu/topology_amd.c index da080d7..c5a6944 100644 --- a/arch/x86/kernel/cpu/topology_amd.c +++ b/arch/x86/kernel/cpu/topology_amd.c @@ -177,8 +177,10 @@ static void topoext_fixup(struct topo_scan *tscan) static void parse_topology_amd(struct topo_scan *tscan) { - if (cpu_feature_enabled(X86_FEATURE_AMD_HTR_CORES)) - tscan->c->topo.cpu_type = cpuid_ebx(0x80000026); + if (cpu_feature_enabled(X86_FEATURE_AMD_HTR_CORES)) { + tscan->c->topo.hw_cpu_type = cpuid_ebx(0x80000026); + tscan->c->topo.cpu_type = get_topology_cpu_type(tscan->c); + } /* * Try to get SMT, CORE, TILE, and DIE shifts from extended diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index cf75134..b9d025f 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -168,8 +168,12 @@ static void parse_topology(struct topo_scan *tscan, bool early) case X86_VENDOR_INTEL: if (!IS_ENABLED(CONFIG_CPU_SUP_INTEL) || !cpu_parse_topology_ext(tscan)) parse_legacy(tscan); - if (c->cpuid_level >= 0x1a) - c->topo.cpu_type = cpuid_eax(0x1a); + + if (c->cpuid_level >= 0x1a) { + c->topo.hw_cpu_type = cpuid_eax(0x1a); + c->topo.cpu_type = get_topology_cpu_type(c); + } + break; } } ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 2/3] x86/topology: Name the AMD core-type values 2026-07-21 15:45 [PATCH v2 0/3] x86/topology: Add support for Low Power cpu_type Vishal Badole 2026-07-21 15:45 ` [PATCH v2 1/3] x86/topo: Map vendor CPU types to generic Linux such types Vishal Badole @ 2026-07-21 15:45 ` Vishal Badole 2026-07-25 1:39 ` [tip: x86/cpu] " tip-bot2 for Vishal Badole 2026-07-21 15:45 ` [PATCH v2 3/3] x86/topology: Add TOPO_CPU_TYPE_LOW_POWER Vishal Badole 2 siblings, 1 reply; 7+ messages in thread From: Vishal Badole @ 2026-07-21 15:45 UTC (permalink / raw) To: tglx, mingo, bp, dave.hansen, x86, hpa, rafael, lenb Cc: linux-kernel, linux-acpi, peterz, tony.luck, chang.seok.bae, wei.w.wang, Vishal Badole Replace the bare 0/1 in get_topology_cpu_type() with named constants that mirror what the AMD APM publishes for CPUID Fn0x80000026 EBX[31:28] (Extended CPU Topology, Core Type): 0 - Performance core 1 - Efficient core 2 - Low-power core (used by a follow-up) No functional change. Suggested-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Vishal Badole <Vishal.Badole@amd.com> --- arch/x86/include/asm/topology.h | 6 ++++++ arch/x86/kernel/cpu/topology_common.c | 4 ++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index ef76ba674f1b..1825691af941 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -114,6 +114,12 @@ enum x86_topology_domains { TOPO_MAX_DOMAIN, }; +enum amd_cpu_type { + AMD_CPU_TYPE_PERFORMANCE = 0, + AMD_CPU_TYPE_EFFICIENCY = 1, + AMD_CPU_TYPE_LOW_POWER = 2, +}; + struct x86_topology_system { unsigned int dom_shifts[TOPO_MAX_DOMAIN]; unsigned int dom_size[TOPO_MAX_DOMAIN]; diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index b9d025f3373a..71b6c33afe0b 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -42,8 +42,8 @@ enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c) } if (c->x86_vendor == X86_VENDOR_AMD) { switch (c->topo.amd_type) { - case 0: return TOPO_CPU_TYPE_PERFORMANCE; - case 1: return TOPO_CPU_TYPE_EFFICIENCY; + case AMD_CPU_TYPE_PERFORMANCE: return TOPO_CPU_TYPE_PERFORMANCE; + case AMD_CPU_TYPE_EFFICIENCY: return TOPO_CPU_TYPE_EFFICIENCY; } } -- 2.34.1 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip: x86/cpu] x86/topology: Name the AMD core-type values 2026-07-21 15:45 ` [PATCH v2 2/3] x86/topology: Name the AMD core-type values Vishal Badole @ 2026-07-25 1:39 ` tip-bot2 for Vishal Badole 0 siblings, 0 replies; 7+ messages in thread From: tip-bot2 for Vishal Badole @ 2026-07-25 1:39 UTC (permalink / raw) To: linux-tip-commits; +Cc: Borislav Petkov (AMD), Vishal Badole, x86, linux-kernel The following commit has been merged into the x86/cpu branch of tip: Commit-ID: bdb1b1f03b9b1cc1cde7d54f8b5b2f9a6bdda782 Gitweb: https://git.kernel.org/tip/bdb1b1f03b9b1cc1cde7d54f8b5b2f9a6bdda782 Author: Vishal Badole <Vishal.Badole@amd.com> AuthorDate: Tue, 21 Jul 2026 21:15:13 +05:30 Committer: Borislav Petkov (AMD) <bp@alien8.de> CommitterDate: Thu, 23 Jul 2026 14:23:27 -07:00 x86/topology: Name the AMD core-type values Replace the bare 0/1 in get_topology_cpu_type() with named constants that mirror what the AMD APM publishes for CPUID Fn0x80000026 EBX[31:28] (Extended CPU Topology, Core Type): 0 - Performance core 1 - Efficient core 2 - Low-power core (used by a follow-up) No functional change. Suggested-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Vishal Badole <Vishal.Badole@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://patch.msgid.link/20260721154514.2506972-3-Vishal.Badole@amd.com --- arch/x86/include/asm/topology.h | 6 ++++++ arch/x86/kernel/cpu/topology_common.c | 4 ++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index ef76ba6..1825691 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -114,6 +114,12 @@ enum x86_topology_domains { TOPO_MAX_DOMAIN, }; +enum amd_cpu_type { + AMD_CPU_TYPE_PERFORMANCE = 0, + AMD_CPU_TYPE_EFFICIENCY = 1, + AMD_CPU_TYPE_LOW_POWER = 2, +}; + struct x86_topology_system { unsigned int dom_shifts[TOPO_MAX_DOMAIN]; unsigned int dom_size[TOPO_MAX_DOMAIN]; diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index b9d025f..71b6c33 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -42,8 +42,8 @@ enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c) } if (c->x86_vendor == X86_VENDOR_AMD) { switch (c->topo.amd_type) { - case 0: return TOPO_CPU_TYPE_PERFORMANCE; - case 1: return TOPO_CPU_TYPE_EFFICIENCY; + case AMD_CPU_TYPE_PERFORMANCE: return TOPO_CPU_TYPE_PERFORMANCE; + case AMD_CPU_TYPE_EFFICIENCY: return TOPO_CPU_TYPE_EFFICIENCY; } } ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 3/3] x86/topology: Add TOPO_CPU_TYPE_LOW_POWER 2026-07-21 15:45 [PATCH v2 0/3] x86/topology: Add support for Low Power cpu_type Vishal Badole 2026-07-21 15:45 ` [PATCH v2 1/3] x86/topo: Map vendor CPU types to generic Linux such types Vishal Badole 2026-07-21 15:45 ` [PATCH v2 2/3] x86/topology: Name the AMD core-type values Vishal Badole @ 2026-07-21 15:45 ` Vishal Badole 2026-07-25 1:39 ` [tip: x86/cpu] " tip-bot2 for Vishal Badole 2 siblings, 1 reply; 7+ messages in thread From: Vishal Badole @ 2026-07-21 15:45 UTC (permalink / raw) To: tglx, mingo, bp, dave.hansen, x86, hpa, rafael, lenb Cc: linux-kernel, linux-acpi, peterz, tony.luck, chang.seok.bae, wei.w.wang, Vishal Badole AMD heterogeneous parts report a third core type via CPUID Fn0x80000026 EBX[31:28] (Extended CPU Topology, Core Type): 0 - Performance 1 - Efficiency 2 - Low Power get_topology_cpu_type() only translates the first two, so on parts that ship low-power cores the third type falls through to TOPO_CPU_TYPE_UNKNOWN. That has two visible effects: - /sys/kernel/debug/x86/topo/cpus/* reports cpu_type "unknown" via get_topology_cpu_type_name(). - amd_get_boost_ratio_numerator() hits the default arm of its x86_topology_cpu_type switch and uses the CPPC_HIGHEST_PERF_PREFCORE fallback instead of scaling by amd_get_highest_perf() as efficiency cores do. Add TOPO_CPU_TYPE_LOW_POWER, translate AMD_CPU_TYPE_LOW_POWER to it in get_topology_cpu_type(), and expose a "low_power" name via get_topology_cpu_type_name(). In amd_get_boost_ratio_numerator(), share the efficiency-core arm of the switch with the new type so low-power cores scale by amd_get_highest_perf() rather than the performance-core ceiling. The new case sits under the existing cpu_feature_enabled(X86_FEATURE_AMD_HTR_CORES) gate and therefore applies to every HTR_CORES-capable AMD/Hygon part that reports core type 2. Signed-off-by: Vishal Badole <Vishal.Badole@amd.com> --- arch/x86/include/asm/processor.h | 1 + arch/x86/kernel/acpi/cppc.c | 3 ++- arch/x86/kernel/cpu/topology_common.c | 3 +++ 3 files changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index fc0350fe8f5e..9e8183441888 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -73,6 +73,7 @@ enum x86_topology_cpu_type { TOPO_CPU_TYPE_ANY = 0, TOPO_CPU_TYPE_PERFORMANCE, TOPO_CPU_TYPE_EFFICIENCY, + TOPO_CPU_TYPE_LOW_POWER, TOPO_CPU_TYPE_UNKNOWN, }; diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c index b8f5dd0a8117..bbade0da5130 100644 --- a/arch/x86/kernel/acpi/cppc.c +++ b/arch/x86/kernel/acpi/cppc.c @@ -281,8 +281,9 @@ int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) /* use the max scale for performance cores */ *numerator = CPPC_HIGHEST_PERF_PERFORMANCE; return 0; + case TOPO_CPU_TYPE_LOW_POWER: case TOPO_CPU_TYPE_EFFICIENCY: - /* use the highest perf value for efficiency cores */ + /* use the highest perf value for efficiency and low-power cores */ ret = amd_get_highest_perf(cpu, &tmp); if (ret) return ret; diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index 71b6c33afe0b..581f2fcd7e42 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -44,6 +44,7 @@ enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c) switch (c->topo.amd_type) { case AMD_CPU_TYPE_PERFORMANCE: return TOPO_CPU_TYPE_PERFORMANCE; case AMD_CPU_TYPE_EFFICIENCY: return TOPO_CPU_TYPE_EFFICIENCY; + case AMD_CPU_TYPE_LOW_POWER: return TOPO_CPU_TYPE_LOW_POWER; } } @@ -57,6 +58,8 @@ const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c) return "performance"; case TOPO_CPU_TYPE_EFFICIENCY: return "efficiency"; + case TOPO_CPU_TYPE_LOW_POWER: + return "low_power"; default: return "unknown"; } -- 2.34.1 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip: x86/cpu] x86/topology: Add TOPO_CPU_TYPE_LOW_POWER 2026-07-21 15:45 ` [PATCH v2 3/3] x86/topology: Add TOPO_CPU_TYPE_LOW_POWER Vishal Badole @ 2026-07-25 1:39 ` tip-bot2 for Vishal Badole 0 siblings, 0 replies; 7+ messages in thread From: tip-bot2 for Vishal Badole @ 2026-07-25 1:39 UTC (permalink / raw) To: linux-tip-commits; +Cc: Vishal Badole, Borislav Petkov (AMD), x86, linux-kernel The following commit has been merged into the x86/cpu branch of tip: Commit-ID: 924be9d673eb75deef2f71ddee0d7d89fe69bb7b Gitweb: https://git.kernel.org/tip/924be9d673eb75deef2f71ddee0d7d89fe69bb7b Author: Vishal Badole <Vishal.Badole@amd.com> AuthorDate: Tue, 21 Jul 2026 21:15:14 +05:30 Committer: Borislav Petkov (AMD) <bp@alien8.de> CommitterDate: Thu, 23 Jul 2026 14:23:47 -07:00 x86/topology: Add TOPO_CPU_TYPE_LOW_POWER AMD heterogeneous parts report a third core type via CPUID Fn0x80000026 EBX[31:28] (Extended CPU Topology, Core Type): 0 - Performance 1 - Efficiency 2 - Low Power get_topology_cpu_type() only translates the first two, so on parts that ship low-power cores the third type falls through to TOPO_CPU_TYPE_UNKNOWN. Add TOPO_CPU_TYPE_LOW_POWER which takes care of this new type. [ bp: Massage commit message, zap the "what" explanation. ] Signed-off-by: Vishal Badole <Vishal.Badole@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://patch.msgid.link/20260721154514.2506972-4-Vishal.Badole@amd.com --- arch/x86/include/asm/processor.h | 1 + arch/x86/kernel/acpi/cppc.c | 3 ++- arch/x86/kernel/cpu/topology_common.c | 3 +++ 3 files changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index fc0350f..9e81834 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -73,6 +73,7 @@ enum x86_topology_cpu_type { TOPO_CPU_TYPE_ANY = 0, TOPO_CPU_TYPE_PERFORMANCE, TOPO_CPU_TYPE_EFFICIENCY, + TOPO_CPU_TYPE_LOW_POWER, TOPO_CPU_TYPE_UNKNOWN, }; diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c index b8f5dd0..bbade0d 100644 --- a/arch/x86/kernel/acpi/cppc.c +++ b/arch/x86/kernel/acpi/cppc.c @@ -281,8 +281,9 @@ int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) /* use the max scale for performance cores */ *numerator = CPPC_HIGHEST_PERF_PERFORMANCE; return 0; + case TOPO_CPU_TYPE_LOW_POWER: case TOPO_CPU_TYPE_EFFICIENCY: - /* use the highest perf value for efficiency cores */ + /* use the highest perf value for efficiency and low-power cores */ ret = amd_get_highest_perf(cpu, &tmp); if (ret) return ret; diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index 71b6c33..581f2fc 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -44,6 +44,7 @@ enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c) switch (c->topo.amd_type) { case AMD_CPU_TYPE_PERFORMANCE: return TOPO_CPU_TYPE_PERFORMANCE; case AMD_CPU_TYPE_EFFICIENCY: return TOPO_CPU_TYPE_EFFICIENCY; + case AMD_CPU_TYPE_LOW_POWER: return TOPO_CPU_TYPE_LOW_POWER; } } @@ -57,6 +58,8 @@ const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c) return "performance"; case TOPO_CPU_TYPE_EFFICIENCY: return "efficiency"; + case TOPO_CPU_TYPE_LOW_POWER: + return "low_power"; default: return "unknown"; } ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2026-07-25 1:40 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2026-07-21 15:45 [PATCH v2 0/3] x86/topology: Add support for Low Power cpu_type Vishal Badole 2026-07-21 15:45 ` [PATCH v2 1/3] x86/topo: Map vendor CPU types to generic Linux such types Vishal Badole 2026-07-25 1:39 ` [tip: x86/cpu] " tip-bot2 for Borislav Petkov (AMD) 2026-07-21 15:45 ` [PATCH v2 2/3] x86/topology: Name the AMD core-type values Vishal Badole 2026-07-25 1:39 ` [tip: x86/cpu] " tip-bot2 for Vishal Badole 2026-07-21 15:45 ` [PATCH v2 3/3] x86/topology: Add TOPO_CPU_TYPE_LOW_POWER Vishal Badole 2026-07-25 1:39 ` [tip: x86/cpu] " tip-bot2 for Vishal Badole
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