[PATCH v6 3/3] x86/kvm: Add AVX512_4VNNIW and AVX512_4FMAPS support

From: He Chen
Date: Fri Nov 11 2016 - 04:26:53 EST


Add two new AVX512 subfeatures support for KVM guest.

AVX512_4VNNIW:
Vector instructions for deep learning enhanced word variable precision.

AVX512_4FMAPS:
Vector instructions for deep learning floating-point single precision.

Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
Signed-off-by: He Chen <he.chen@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index afa7bbb..ddcdf7c 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -16,6 +16,7 @@
#include <linux/export.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
+#include <asm/processor.h>
#include <asm/fpu/internal.h> /* For use_eager_fpu. Ugh! */
#include <asm/user.h>
#include <asm/fpu/xstate.h>
@@ -65,6 +66,11 @@ u64 kvm_supported_xcr0(void)

#define F(x) bit(X86_FEATURE_##x)

+/* These are scattered features in cpufeatures.h. */
+#define KVM_CPUID_BIT_AVX512_4VNNIW 2
+#define KVM_CPUID_BIT_AVX512_4FMAPS 3
+#define KF(x) bit(KVM_CPUID_BIT_##x)
+
int kvm_update_cpuid(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
@@ -376,6 +382,10 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
/* cpuid 7.0.ecx*/
const u32 kvm_cpuid_7_0_ecx_x86_features = F(PKU) | 0 /*OSPKE*/;

+ /* cpuid 7.0.edx*/
+ const u32 kvm_cpuid_7_0_edx_x86_features =
+ KF(AVX512_4VNNIW) | KF(AVX512_4FMAPS);
+
/* all calls to cpuid_count() should be made on the same cpu */
get_cpu();

@@ -458,12 +468,14 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
/* PKU is not yet implemented for shadow paging. */
if (!tdp_enabled)
entry->ecx &= ~F(PKU);
+ entry->edx &= kvm_cpuid_7_0_edx_x86_features;
+ entry->edx &= get_scattered_cpuid_leaf(7, 0, CPUID_EDX);
} else {
entry->ebx = 0;
entry->ecx = 0;
+ entry->edx = 0;
}
entry->eax = 0;
- entry->edx = 0;
break;
}
case 9:
--
2.7.4