From 24d74b9f5f2a972ac9228372adeac62b2dc10ea2 Mon Sep 17 00:00:00 2001 From: Jiaxi Chen Date: Fri, 25 Nov 2022 20:58:43 +0800 Subject: [PATCH] KVM: x86: Advertise AVX-VNNI-INT8 CPUID to user space AVX-VNNI-INT8 is a new set of instructions in the latest Intel platform Sierra Forest, aims for the platform to have superior AI capabilities. This instruction multiplies the individual bytes of two unsigned or unsigned source operands, then adds and accumulates the results into the destination dword element size operand. The bit definition: CPUID.(EAX=7,ECX=1):EDX[bit 4] AVX-VNNI-INT8 is on a new and sparse CPUID leaf and all bits on this leaf have no truly kernel use case for now. Given that and to save space for kernel feature bits, move this new leaf to KVM-only subleaf and plus an x86_FEATURE definition for AVX-VNNI-INT8 to direct it to the KVM entry. Advertise AVX-VNNI-INT8 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 Message-Id: <20221125125845.1182922-7-jiaxi.chen@linux.intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/cpuid.c | 6 +++++- arch/x86/kvm/reverse_cpuid.h | 5 +++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 5dfc0d036df5..b6ce47c4e972 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -667,6 +667,10 @@ void kvm_set_cpu_caps(void) F(AVX_IFMA) ); + kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX, + F(AVX_VNNI_INT8) + ); + kvm_cpu_cap_mask(CPUID_D_1_EAX, F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES) | f_xfd ); @@ -920,9 +924,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) goto out; cpuid_entry_override(entry, CPUID_7_1_EAX); + cpuid_entry_override(entry, CPUID_7_1_EDX); entry->ebx = 0; entry->ecx = 0; - entry->edx = 0; } break; case 0xa: { /* Architectural Performance Monitoring */ diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h index 443a6b3e66c0..84f56b662424 100644 --- a/arch/x86/kvm/reverse_cpuid.h +++ b/arch/x86/kvm/reverse_cpuid.h @@ -13,6 +13,7 @@ */ enum kvm_only_cpuid_leafs { CPUID_12_EAX = NCAPINTS, + CPUID_7_1_EDX, NR_KVM_CPU_CAPS, NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, @@ -36,6 +37,9 @@ enum kvm_only_cpuid_leafs { #define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0) #define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1) +/* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */ +#define X86_FEATURE_AVX_VNNI_INT8 KVM_X86_FEATURE(CPUID_7_1_EDX, 4) + struct cpuid_reg { u32 function; u32 index; @@ -60,6 +64,7 @@ static const struct cpuid_reg reverse_cpuid[] = { [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX}, [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX}, [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX}, + [CPUID_7_1_EDX] = { 7, 1, CPUID_EDX}, }; /* -- GitLab