[PATCH] x86/cpufeatures: Define X86_FEATURE_PREFETCHI (AMD)

[Babu Moger <babu.moger@amd.com>]

The latest AMD platform has introduced a new instruction called PREFETCHI.
This instruction loads a cache line from a specified memory address into
the indicated data or instruction cache level, based on locality reference
hints.

Feature bit definition:
CPUID_Fn80000021_EAX [bit 20] - Indicates support for IC prefetch.

This feature is analogous to Intel's PREFETCHITI (CPUID.(EAX=7,ECX=1):EDX),
though the CPUID bit definitions differ between AMD and Intel.

Expose the feature to KVM guests.

The feature is documented in Processor Programming Reference (PPR)
for AMD Family 1Ah Model 02h, Revision C1 (Link below).

Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Signed-off-by: Babu Moger <babu.moger@amd.com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kvm/cpuid.c               | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 6c2c152d8a67..7d7507b3eefd 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -457,6 +457,7 @@
 #define X86_FEATURE_AUTOIBRS		(20*32+ 8) /* Automatic IBRS */
 #define X86_FEATURE_NO_SMM_CTL_MSR	(20*32+ 9) /* SMM_CTL MSR is not present */
 
+#define X86_FEATURE_PREFETCHI		(20*32+20) /* Prefetch Data/Instruction to Cache Level */
 #define X86_FEATURE_SBPB		(20*32+27) /* Selective Branch Prediction Barrier */
 #define X86_FEATURE_IBPB_BRTYPE		(20*32+28) /* MSR_PRED_CMD[IBPB] flushes all branch type predictions */
 #define X86_FEATURE_SRSO_NO		(20*32+29) /* CPU is not affected by SRSO */
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 5e4d4934c0d3..fba018a730ab 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1178,6 +1178,7 @@ void kvm_set_cpu_caps(void)
 		/* SmmPgCfgLock */
 		F(NULL_SEL_CLR_BASE),
 		F(AUTOIBRS),
+		F(PREFETCHI),
 		EMULATED_F(NO_SMM_CTL_MSR),
 		/* PrefetchCtlMsr */
 		F(WRMSR_XX_BASE_NS),
-- 
2.34.1