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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>
hifive-unleashed-5.1
Kan Liang 2019-02-04 14:23:29 -08:00 committed by Ingo Molnar
parent 0237199186
commit 0f42b790c9
2 changed files with 59 additions and 0 deletions
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28
arch/x86/include/asm/cpu_device_id.h
View File

@ -11,4 +11,32 @@
extern const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match);
/*
* Match specific microcode revisions.
*
* vendor/family/model/stepping must be all set.
*
* Only checks against the boot CPU. When mixed-stepping configs are
* valid for a CPU model, add a quirk for every valid stepping and
* do the fine-tuning in the quirk handler.
*/
struct x86_cpu_desc {
__u8 x86_family;
__u8 x86_vendor;
__u8 x86_model;
__u8 x86_stepping;
__u32 x86_microcode_rev;
};
#define INTEL_CPU_DESC(mod, step, rev) { \
.x86_family = 6, \
.x86_vendor = X86_VENDOR_INTEL, \
.x86_model = mod, \
.x86_stepping = step, \
.x86_microcode_rev = rev, \
}
extern bool x86_cpu_has_min_microcode_rev(const struct x86_cpu_desc *table);
#endif

31
arch/x86/kernel/cpu/match.c
View File

@ -48,3 +48,34 @@ const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match)
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);