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KVM: x86: Advertise PREFETCHIT0/1 CPUID to user space

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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]

PREFETCHIT0/1 is on a KVM-only subleaf. Plus an x86_FEATURE definition
for this feature bit to direct it to the KVM entry.

Advertise PREFETCHIT0/1 to KVM userspace. This is safe because there are
no new VMX controls or additional host enabling required for guests to
use this feature.

Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
Message-Id: <20221125125845.1182922-9-jiaxi.chen@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jiaxi Chen 2022-11-25 20:58:45 +08:00 committed by Paolo Bonzini
parent 9977f0877d
commit 29c46979b2
2 changed files with 2 additions and 1 deletions
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2
arch/x86/kvm/cpuid.c
View File

@ -668,7 +668,7 @@ void kvm_set_cpu_caps(void)
);
kvm_cpu_cap_init_kvm_defined(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,

1
arch/x86/kvm/reverse_cpuid.h
View File

@ -40,6 +40,7 @@ enum kvm_only_cpuid_leafs {
/* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */
#define X86_FEATURE_AVX_VNNI_INT8 KVM_X86_FEATURE(CPUID_7_1_EDX, 4)
#define X86_FEATURE_AVX_NE_CONVERT KVM_X86_FEATURE(CPUID_7_1_EDX, 5)
#define X86_FEATURE_PREFETCHITI KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
struct cpuid_reg {
u32 function;