Commit 0f42b790 authored by Kan Liang's avatar Kan Liang Committed by Ingo Molnar
Browse files

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: default avatarAndi Kleen <ak@linux.intel.com>
Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarKan Liang <kan.liang@linux.intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent 02371991

arch/x86/include/asm/cpu_device_id.h

+28 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/cpu/match.c

+31 −0
Original line number Diff line number Diff line
@@ -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);

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