Commit 29c46979 authored by Jiaxi Chen's avatar Jiaxi Chen Committed by Paolo Bonzini
Browse files

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



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: default avatarJiaxi Chen <jiaxi.chen@linux.intel.com>
Message-Id: <20221125125845.1182922-9-jiaxi.chen@linux.intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 9977f087

arch/x86/kvm/cpuid.c

+1 −1
Original line number Diff line number Diff line
@@ -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,

arch/x86/kvm/reverse_cpuid.h

+1 −0
Original line number Diff line number Diff line
@@ -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;