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x86/lib: Add CPUID(0x1) family and model calculation

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The x86 library provides x86_family() and x86_model().  They take raw
CPUID register output and calculate the CPU family and model from it.

In follow-up work, the x86 subsystem will use APIs which access
previously-parsed CPUID leafs structure instead of doing direct CPUID queries.
These new APIs force using the auto generated leaf data types at
<asm/cpuid/leaf_types.h>.

Introduce x86 family and model calculation functions that take these
auto-generated data types.  Refactor the original code so that no logic is
duplicated.

  [ bp: Massage commit message, unbreak too long line. ]

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/20260528153923.403473-11-darwi@linutronix.de
This commit is contained in:
Ahmed S. Darwish 2026-05-28 17:37:32 +02:00 committed by Borislav Petkov (AMD)
parent 21532edff7
commit 21834b541d
2 changed files with 37 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/cpu.h
View File

@ -7,7 +7,9 @@
#include <linux/topology.h>
#include <linux/nodemask.h>
#include <linux/percpu.h>
#include <asm/ibt.h>
#include <asm/cpuid/leaf_types.h>
#ifndef CONFIG_SMP
#define cpu_physical_id(cpu) boot_cpu_physical_apicid
@ -24,6 +26,10 @@ int mwait_usable(const struct cpuinfo_x86 *);
unsigned int x86_family(unsigned int sig);
unsigned int x86_model(unsigned int sig);
unsigned int x86_stepping(unsigned int sig);
unsigned int cpuid_family(const struct leaf_0x1_0 *l);
unsigned int cpuid_model(const struct leaf_0x1_0 *l);
#ifdef CONFIG_X86_BUS_LOCK_DETECT
extern void __init sld_setup(struct cpuinfo_x86 *c);
extern bool handle_user_split_lock(struct pt_regs *regs, long error_code);

49
arch/x86/lib/cpu.c
View File

@ -1,33 +1,36 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/types.h>
#include <linux/export.h>
#include <asm/cpu.h>
#include <asm/cpuid/leaf_types.h>
static unsigned int __x86_family(unsigned int base_fam, unsigned int ext_fam)
{
if (base_fam == 0xf)
base_fam += ext_fam;
return base_fam;
}
static unsigned int __x86_model(unsigned int family, unsigned int base_model,
unsigned int ext_model)
{
if (family >= 0x6)
base_model |= ext_model << 4;
return base_model;
}
unsigned int x86_family(unsigned int sig)
{
unsigned int x86;
x86 = (sig >> 8) & 0xf;
if (x86 == 0xf)
x86 += (sig >> 20) & 0xff;
return x86;
return __x86_family((sig >> 8) & 0xf, (sig >> 20) & 0xff);
}
EXPORT_SYMBOL_GPL(x86_family);
unsigned int x86_model(unsigned int sig)
{
unsigned int fam, model;
fam = x86_family(sig);
model = (sig >> 4) & 0xf;
if (fam >= 0x6)
model += ((sig >> 16) & 0xf) << 4;
return model;
return __x86_model(x86_family(sig), (sig >> 4) & 0xf, (sig >> 16) & 0xf);
}
EXPORT_SYMBOL_GPL(x86_model);
@ -36,3 +39,13 @@ unsigned int x86_stepping(unsigned int sig)
return sig & 0xf;
}
EXPORT_SYMBOL_GPL(x86_stepping);
unsigned int cpuid_family(const struct leaf_0x1_0 *l)
{
return __x86_family(l->base_family_id, l->ext_family);
}
unsigned int cpuid_model(const struct leaf_0x1_0 *l)
{
return __x86_model(cpuid_family(l), l->base_model, l->ext_model);
}