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KVM: x86: expose AVX512_BF16 feature to guest 

AVX512 BFLOAT16 instructions support 16-bit BFLOAT16 floating-point
format (BF16) for deep learning optimization.

Intel adds AVX512 BFLOAT16 feature in CooperLake, which is CPUID.7.1.EAX[5].

Detailed information of the CPUID bit can be found here,
https://software.intel.com/sites/default/files/managed/c5/15/\
architecture-instruction-set-extensions-programming-reference.pdf.

Signed-off-by: Jing Liu <jing2.liu@linux.intel.com>
[Fix type mismatch in min, changing constant "1" to "1u". - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jing Liu 2019-07-11 13:49:57 +08:00 committed by Paolo Bonzini
parent 964a4eacef
commit 0b77462951
1 changed files with 11 additions and 1 deletions
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12
arch/x86/kvm/cpuid.c
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@ -368,9 +368,13 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) |
F(MD_CLEAR);
/* cpuid 7.1.eax */
const u32 kvm_cpuid_7_1_eax_x86_features =
F(AVX512_BF16);
switch (index) {
case 0:
entry->eax = 0;
entry->eax = min(entry->eax, 1u);
entry->ebx &= kvm_cpuid_7_0_ebx_x86_features;
cpuid_mask(&entry->ebx, CPUID_7_0_EBX);
/* TSC_ADJUST is emulated */
@ -394,6 +398,12 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
*/
entry->edx |= F(ARCH_CAPABILITIES);
break;
case 1:
entry->eax &= kvm_cpuid_7_1_eax_x86_features;
entry->ebx = 0;
entry->ecx = 0;
entry->edx = 0;
break;
default:
WARN_ON_ONCE(1);
entry->eax = 0;