[PATCH 6/6] x86: KVM: Enable PREFETCHIT0/1 CPUID and expose it to guest

Jiaxi Chen
2022-10-19T09:02:15Z

Latest Intel platform Granite Rapids has introduced a new instruction -
PREFETCHIT0/1, which moves code to memory (cache) closer to the processor
depending on specific hints.

The bit definition:
CPUID.(EAX=7,ECX=1):EDX[bit 14]

This patch enables this CPUID in the kernel feature bits and expose it
to guest OS.

Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/kvm/cpuid.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 4e0bbffedbb4..de8aa62bbdb1 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -426,6 +426,7 @@
/* Intel-defined CPU features, CPUID level 0x00000007:1 (EDX), word 20 */
#define X86_FEATURE_AVX_VNNI_INT8 (20*32+ 4) /* Support for VPDPB[SU,UU,SS]D[,S] */
#define X86_FEATURE_AVX_NE_CONVERT (20*32+ 5) /* AVX NE CONVERT Instructions */
+#define X86_FEATURE_PREFETCHITI (20*32+14) /* PREFETCHIT0/1 Instructions */

/*
* BUG word(s)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index fcd00c68e546..e73307732d10 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -661,7 +661,7 @@ void kvm_set_cpu_caps(void)
F(AVX_IFMA));

kvm_cpu_cap_mask(CPUID_7_1_EDX,
- F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT)
+ F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT) | F(PREFETCHITI)
);

kvm_cpu_cap_mask(CPUID_D_1_EAX,
--
2.27.0