Commit c7107750 authored by Perry Yuan's avatar Perry Yuan Committed by Mario Limonciello
Browse files

x86/cpufeatures: Add AMD FAST CPPC feature flag 



Some AMD Zen 4 processors support a new feature FAST CPPC which
allows for a faster CPPC loop due to internal architectural
enhancements. The goal of this faster loop is higher performance
at the same power consumption.

Reference:
See the page 99 of PPR for AMD Family 19h Model 61h rev.B1, docID 56713

Signed-off-by: default avatarPerry Yuan <perry.yuan@amd.com>
Signed-off-by: default avatarXiaojian Du <Xiaojian.Du@amd.com>
Reviewed-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
parent 83a7eefe

arch/x86/include/asm/cpufeatures.h

+1 −0
Original line number Diff line number Diff line
@@ -470,6 +470,7 @@ 
#define X86_FEATURE_BHI_CTRL		(21*32+ 2) /* "" BHI_DIS_S HW control available */

#define X86_FEATURE_CLEAR_BHB_HW	(21*32+ 3) /* "" BHI_DIS_S HW control enabled */

#define X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT (21*32+ 4) /* "" Clear branch history at vmexit using SW loop */

#define X86_FEATURE_FAST_CPPC		(21*32 + 5) /* "" AMD Fast CPPC */



/*

 * BUG word(s)

arch/x86/kernel/cpu/scattered.c

+1 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ static const struct cpuid_bit cpuid_bits[] = { 
	{ X86_FEATURE_HW_PSTATE,	CPUID_EDX,  7, 0x80000007, 0 },

	{ X86_FEATURE_CPB,		CPUID_EDX,  9, 0x80000007, 0 },

	{ X86_FEATURE_PROC_FEEDBACK,    CPUID_EDX, 11, 0x80000007, 0 },

	{ X86_FEATURE_FAST_CPPC, 	CPUID_EDX, 15, 0x80000007, 0 },

	{ X86_FEATURE_MBA,		CPUID_EBX,  6, 0x80000008, 0 },

	{ X86_FEATURE_SMBA,		CPUID_EBX,  2, 0x80000020, 0 },

	{ X86_FEATURE_BMEC,		CPUID_EBX,  3, 0x80000020, 0 },