linux/arch/x86/kernel/cpu/match.c
Kan Liang 0f42b790c9 x86/cpufeature: Add facility to check for min microcode revisions
For bug workarounds or checks, it is useful to check for specific
microcode revisions.

Add a new generic function to match the CPU with stepping.
Add the other function to check the min microcode revisions for
the matched CPU.

A new table format is introduced to facilitate the quirk to
fill the related information.

This does not change the existing x86_cpu_id because it's an ABI
shared with modules, and also has quite different requirements,
as in no wildcards, but everything has to be matched exactly.

Originally-by: Andi Kleen <ak@linux.intel.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: eranian@google.com
Link: https://lkml.kernel.org/r/1549319013-4522-1-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-11 07:59:23 +01:00

82 lines
2.4 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <asm/cpu_device_id.h>
#include <asm/cpufeature.h>
#include <linux/cpu.h>
#include <linux/export.h>
#include <linux/slab.h>
/**
* x86_match_cpu - match current CPU again an array of x86_cpu_ids
* @match: Pointer to array of x86_cpu_ids. Last entry terminated with
* {}.
*
* Return the entry if the current CPU matches the entries in the
* passed x86_cpu_id match table. Otherwise NULL. The match table
* contains vendor (X86_VENDOR_*), family, model and feature bits or
* respective wildcard entries.
*
* A typical table entry would be to match a specific CPU
* { X86_VENDOR_INTEL, 6, 0x12 }
* or to match a specific CPU feature
* { X86_FEATURE_MATCH(X86_FEATURE_FOOBAR) }
*
* Fields can be wildcarded with %X86_VENDOR_ANY, %X86_FAMILY_ANY,
* %X86_MODEL_ANY, %X86_FEATURE_ANY or 0 (except for vendor)
*
* Arrays used to match for this should also be declared using
* MODULE_DEVICE_TABLE(x86cpu, ...)
*
* This always matches against the boot cpu, assuming models and features are
* consistent over all CPUs.
*/
const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match)
{
const struct x86_cpu_id *m;
struct cpuinfo_x86 *c = &boot_cpu_data;
for (m = match; m->vendor | m->family | m->model | m->feature; m++) {
if (m->vendor != X86_VENDOR_ANY && c->x86_vendor != m->vendor)
continue;
if (m->family != X86_FAMILY_ANY && c->x86 != m->family)
continue;
if (m->model != X86_MODEL_ANY && c->x86_model != m->model)
continue;
if (m->feature != X86_FEATURE_ANY && !cpu_has(c, m->feature))
continue;
return m;
}
return NULL;
}
EXPORT_SYMBOL(x86_match_cpu);
static const struct x86_cpu_desc *
x86_match_cpu_with_stepping(const struct x86_cpu_desc *match)
{
struct cpuinfo_x86 *c = &boot_cpu_data;
const struct x86_cpu_desc *m;
for (m = match; m->x86_family | m->x86_model; m++) {
if (c->x86_vendor != m->x86_vendor)
continue;
if (c->x86 != m->x86_family)
continue;
if (c->x86_model != m->x86_model)
continue;
if (c->x86_stepping != m->x86_stepping)
continue;
return m;
}
return NULL;
}
bool x86_cpu_has_min_microcode_rev(const struct x86_cpu_desc *table)
{
const struct x86_cpu_desc *res = x86_match_cpu_with_stepping(table);
if (!res || res->x86_microcode_rev > boot_cpu_data.microcode)
return false;
return true;
}
EXPORT_SYMBOL_GPL(x86_cpu_has_min_microcode_rev);