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(-)
On Wed, Jul 08, 2026 at 01:24:05AM +0200, Thomas Gleixner wrote:
> If that's the only case to handle, then sure that open coded check is
> fine.
This is ontop of tip:x86/cpu which already has Pawan's change that drops the
one Intel-specific CPU type use.
It boots here so... :-P
---
From: "Borislav Petkov (AMD)" <bp@alien8.de>
Date: Thu, 2 Jul 2026 17:00:28 -0700
Subject: [PATCH] x86/topo: Map vendor CPU types to generic Linux such types
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
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>
Link: https://lore.kernel.org/r/20260629094349.533301-2-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 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;
}
}
--
2.53.0
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquetteOn Mon, Jul 20, 2026 at 08:18:58PM -0700, Borislav Petkov wrote:
> On Wed, Jul 08, 2026 at 01:24:05AM +0200, Thomas Gleixner wrote:
> > If that's the only case to handle, then sure that open coded check is
> > fine.
>
> This is ontop of tip:x86/cpu which already has Pawan's change that drops the
> one Intel-specific CPU type use.
>
> It boots here so... :-P
>
> ---
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
> Date: Thu, 2 Jul 2026 17:00:28 -0700
> Subject: [PATCH] x86/topo: Map vendor CPU types to generic Linux such types
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
>
> 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>
> Link: https://lore.kernel.org/r/20260629094349.533301-2-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 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,
I don't really understand the purpose of TOPO_CPU_TYPE_ANY here. In the cpu
matching infrastructure, X86_CPU_TYPE_ANY makes sense. Here I fail to
understand how is TOPO_CPU_TYPE_ANY different from UNKNOWN? A table passed
to x86_match_cpu() with X86_CPU_TYPE_ANY entry will match any CPU type
including TOPO_CPU_TYPE_UNKNOWN.
> + 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,
> -};
...
> /**
> * 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)
In line with what Thomas pointed that cpu_type is not a system property, I
suggest matching cpu_type should be dropped from x86_match_cpu(). More so
because it only uses boot_cpu_data and misses the other types of secondary
CPUs. I feel it is not a reliable way to match CPU types. Thoughts?
> 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)) {
Slightly unrelated to this patch, on AMD is it that hw_cpu_type only
available on hybrid systems? On Intel ...
> + 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);
... hw_cpu_type could be enumerated on non-hybrid parts.
> + }
> +
> break;
> }
> }
On Wed, Jul 22, 2026 at 11:09:58AM -0700, Pawan Gupta wrote:
> > +enum x86_topology_cpu_type {
> > + /* X86_CPU_TYPE_ANY */
> > + TOPO_CPU_TYPE_ANY = 0,
>
> I don't really understand the purpose of TOPO_CPU_TYPE_ANY here. In the cpu
> matching infrastructure, X86_CPU_TYPE_ANY makes sense. Here I fail to
> understand how is TOPO_CPU_TYPE_ANY different from UNKNOWN? A table passed
> to x86_match_cpu() with X86_CPU_TYPE_ANY entry will match any CPU type
> including TOPO_CPU_TYPE_UNKNOWN.
This will go away in future patches. We do one logical thing per patch and
removing UNKNOWN is not it. I have it on my TODO list to clean up everything
here.
>
> > + TOPO_CPU_TYPE_PERFORMANCE,
> > + TOPO_CPU_TYPE_EFFICIENCY,
> > + TOPO_CPU_TYPE_UNKNOWN,
> > +};
...
> > @@ -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)
>
> In line with what Thomas pointed that cpu_type is not a system property, I
> suggest matching cpu_type should be dropped from x86_match_cpu(). More so
> because it only uses boot_cpu_data and misses the other types of secondary
> CPUs. I feel it is not a reliable way to match CPU types. Thoughts?
How do you suggest we match CPU types on the whole system?
I.e., "do this workaround only on the performance cores", for example.
c->topo.cpu_type is perfect for that then.
> Slightly unrelated to this patch, on AMD is it that hw_cpu_type only
> available on hybrid systems?
No idea. I will dig through that later, when cleaning up.
If only available on hybrid systems, we will have to fake something there,
X86_CPU_TYPE_ANY perhaps.
:-)
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Wed, Jul 22, 2026 at 11:31:52AM -0700, Borislav Petkov wrote:
> On Wed, Jul 22, 2026 at 11:09:58AM -0700, Pawan Gupta wrote:
> > > +enum x86_topology_cpu_type {
> > > + /* X86_CPU_TYPE_ANY */
> > > + TOPO_CPU_TYPE_ANY = 0,
> >
> > I don't really understand the purpose of TOPO_CPU_TYPE_ANY here. In the cpu
> > matching infrastructure, X86_CPU_TYPE_ANY makes sense. Here I fail to
> > understand how is TOPO_CPU_TYPE_ANY different from UNKNOWN? A table passed
> > to x86_match_cpu() with X86_CPU_TYPE_ANY entry will match any CPU type
> > including TOPO_CPU_TYPE_UNKNOWN.
>
> This will go away in future patches. We do one logical thing per patch and
> removing UNKNOWN is not it. I have it on my TODO list to clean up everything
> here.
Unless I am misreading, TOPO_CPU_TYPE_ANY is introduced in this patch.
X86_*_ANY in x86_match_cpu() are much needed wildcards, I dont really
understand why x86_topology_cpu_type needs to carry a wildcard. It should
reflect the true state, PERFORMANCE, EFFICIENCY or UNKNOWN.
Between ANY and UNKNOWN, I would prefer UNKNOWN when CPU did not report a
type.
> >
> > > + TOPO_CPU_TYPE_PERFORMANCE,
> > > + TOPO_CPU_TYPE_EFFICIENCY,
> > > + TOPO_CPU_TYPE_UNKNOWN,
> > > +};
>
> ...
>
> > > @@ -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)
> >
> > In line with what Thomas pointed that cpu_type is not a system property, I
> > suggest matching cpu_type should be dropped from x86_match_cpu(). More so
> > because it only uses boot_cpu_data and misses the other types of secondary
> > CPUs. I feel it is not a reliable way to match CPU types. Thoughts?
>
> How do you suggest we match CPU types on the whole system?
>
> I.e., "do this workaround only on the performance cores", for example.
>
> c->topo.cpu_type is perfect for that then.
Ya. If need be, a mask of each possible cpu_type can be built for
dispatching work selectively.
On Wed, Jul 22, 2026 at 12:22:11PM -0700, Pawan Gupta wrote:
> Unless I am misreading, TOPO_CPU_TYPE_ANY is introduced in this patch.
> X86_*_ANY in x86_match_cpu() are much needed wildcards, I dont really
> understand why x86_topology_cpu_type needs to carry a wildcard. It should
> reflect the true state, PERFORMANCE, EFFICIENCY or UNKNOWN.
>
> Between ANY and UNKNOWN, I would prefer UNKNOWN when CPU did not report a
> type.
Because X86_CPU_TYPE_ANY is already there and it is 0 and TOPO_CPU_TYPE_ANY is
supposed to be the same and mirror it.
Did you even read my mail where I explain that we don't do multiple things in
one patch?
> Ya. If need be, a mask of each possible cpu_type can be built for
> dispatching work selectively.
Instead of doing the completely sensible thing and keeping a per-CPU type?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Wed, Jul 22, 2026 at 12:51:05PM -0700, Borislav Petkov wrote: > On Wed, Jul 22, 2026 at 12:22:11PM -0700, Pawan Gupta wrote: > > Unless I am misreading, TOPO_CPU_TYPE_ANY is introduced in this patch. > > X86_*_ANY in x86_match_cpu() are much needed wildcards, I dont really > > understand why x86_topology_cpu_type needs to carry a wildcard. It should > > reflect the true state, PERFORMANCE, EFFICIENCY or UNKNOWN. > > > > Between ANY and UNKNOWN, I would prefer UNKNOWN when CPU did not report a > > type. > > Because X86_CPU_TYPE_ANY is already there and it is 0 and TOPO_CPU_TYPE_ANY is > supposed to be the same and mirror it. This is exactly what I don't understand. For a wildcard X86_CPU_TYPE_ANY that matches TOPO_CPU_TYPE_*, do we really need TOPO_CPU_TYPE_ANY for matching to work? > Did you even read my mail where I explain that we don't do multiple things in > one patch? Yes, but my main concern is about addition of TOPO_CPU_TYPE_ANY. If we don't add TOPO_CPU_TYPE_ANY, second patch will not be needed. Sorry if I am mis-interpreting things. > > Ya. If need be, a mask of each possible cpu_type can be built for > > dispatching work selectively. > > Instead of doing the completely sensible thing and keeping a per-CPU type? My earlier comment was unnecessary, and putting us off-track here. Please ignore this part. (Just to clarify what I meant: For dispatching work to all P-cores in your example scenario with something like on_each_cpu_mask() we would need a mask of all P-cores. Such a mask can be built/cached using the per-CPU type information).
On Wed, Jul 22, 2026 at 01:57:57PM -0700, Pawan Gupta wrote:
> Yes, but my main concern is about addition of TOPO_CPU_TYPE_ANY. If we
> don't add TOPO_CPU_TYPE_ANY, second patch will not be needed. Sorry if I am
> mis-interpreting things.
Well, I have no idea too what are you even fighting for? It sounds like
a giant waste of time to me for something as trivial as this.
What second patch?
Once the cleanup is done, only one of the two will survive - either
TOPO_CPU_TYPE_ANY or TOPO_CPU_TYPE_UNKNOWN. I'm calling the former "ANY" to
denote that it is the *same* ANY as X86_CPU_TYPE_ANY.
I don't know how else to explain it to you.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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