From 0b774629512057b4becc705e2495220844e6e795 Mon Sep 17 00:00:00 2001
From: Jing Liu <jing2.liu@linux.intel.com>
Date: Thu, 11 Jul 2019 13:49:57 +0800
Subject: [PATCH] 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>
---
arch/x86/kvm/cpuid.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index ead6812103063..22c2720cd948e 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -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;
--
2.39.5