archives/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-03-08 04:04:43 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

KVM: x86: Advertise AVX10_VNNI_INT CPUID to userspace

Browse source 
Define and advertise AVX10_VNNI_INT CPUID to userspace when it's supported
by the host.

AVX10_VNNI_INT (0x24.0x1.ECX[bit 2]) is a discrete feature bit
introduced on Intel Diamond Rapids, which enumerates the support for
EVEX VPDP* instructions for INT8/INT16 [*].

Since this feature has no actual kernel usages, define it as a KVM-only
feature in reverse_cpuid.h.

Advertise new CPUID subleaf 0x24.0x1 with AVX10_VNNI_INT bit to
userspace for guest use. It's safe since no additional enabling work
is needed in the host kernel.

[*]: Intel Advanced Vector Extensions 10.2 Architecture Specification
     (rev 5.0).

Tested-by: Xudong Hao <xudong.hao@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://patch.msgid.link/20251120050720.931449-5-zhao1.liu@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Zhao Liu 2025-11-20 13:07:20 +08:00 • committed by Sean Christopherson
parent 2ff8fb1e65
commit 062768f426
3 changed files with 22 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

1
arch/x86/include/asm/kvm_host.h
View file

@ -777,6 +777,7 @@ enum kvm_only_cpuid_leafs {
CPUID_8000_0021_ECX,
CPUID_7_1_ECX,
CPUID_1E_1_EAX,
CPUID_24_1_ECX,
NR_KVM_CPU_CAPS,
NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,

18
arch/x86/kvm/cpuid.c
View file

@ -1084,6 +1084,10 @@ void kvm_set_cpu_caps(void)
F(AVX10_512),
);
kvm_cpu_cap_init(CPUID_24_1_ECX,
F(AVX10_VNNI_INT),
);
kvm_cpu_cap_init(CPUID_8000_0001_ECX,
F(LAHF_LM),
F(CMP_LEGACY),
@ -1661,6 +1665,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
break;
}
max_idx = entry->eax = min(entry->eax, 1u);
/*
* The AVX10 version is encoded in EBX[7:0]. Note, the version
* is guaranteed to be >=1 if AVX10 is supported. Note #2, the
@ -1670,9 +1675,20 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
cpuid_entry_override(entry, CPUID_24_0_EBX);
entry->ebx |= avx10_version;
entry->eax = 0;
entry->ecx = 0;
entry->edx = 0;
/* KVM only supports up to 0x24.0x1, capped above via min(). */
if (max_idx >= 1) {
entry = do_host_cpuid(array, function, 1);
if (!entry)
goto out;
cpuid_entry_override(entry, CPUID_24_1_ECX);
entry->eax = 0;
entry->ebx = 0;
entry->edx = 0;
}
break;
}
case KVM_CPUID_SIGNATURE: {

4
arch/x86/kvm/reverse_cpuid.h
View file

@ -63,6 +63,9 @@
#define X86_FEATURE_AVX10_256 KVM_X86_FEATURE(CPUID_24_0_EBX, 17)
#define X86_FEATURE_AVX10_512 KVM_X86_FEATURE(CPUID_24_0_EBX, 18)
/* Intel-defined sub-features, CPUID level 0x00000024:1 (ECX) */
#define X86_FEATURE_AVX10_VNNI_INT KVM_X86_FEATURE(CPUID_24_1_ECX, 2)
/* CPUID level 0x80000007 (EDX). */
#define KVM_X86_FEATURE_CONSTANT_TSC KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8)
@ -105,6 +108,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
[CPUID_8000_0021_ECX] = {0x80000021, 0, CPUID_ECX},
[CPUID_7_1_ECX] = { 7, 1, CPUID_ECX},
[CPUID_1E_1_EAX] = { 0x1e, 1, CPUID_EAX},
[CPUID_24_1_ECX] = { 0x24, 1, CPUID_ECX},
};
/*