[PATCH v2] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS features to kvm guest

[He Chen]

The spec can be found in Intel Software Developer Manual or in
Instruction Set Extensions Programming Reference.

Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
Signed-off-by: He Chen <he.chen@xxxxxxxxxxxxxxx>
---
Changes in v2:
* add new macros for new AVX512 scattered features
* add a cpuid_count_edx function to processor.h
---
 arch/x86/include/asm/processor.h |  9 +++++++++
 arch/x86/kvm/cpuid.c             | 13 ++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 984a7bf..e5ad7a74 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -577,6 +577,15 @@ static inline unsigned int cpuid_edx(unsigned int op)
 	return edx;
 }
 
+static inline unsigned int cpuid_count_edx(unsigned op, unsigned count)
+{
+	unsigned int eax, ebx, ecx, edx;
+
+	cpuid_count(op, count, &eax, &ebx, &ecx, &edx);
+
+	return edx;
+}
+
 /* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
 static __always_inline void rep_nop(void)
 {
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index afa7bbb..9990e7a 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -65,6 +65,11 @@ 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 +381,10 @@ 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 +467,14 @@ 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 &= cpuid_count_edx(7, 0);
 		} else {
 			entry->ebx = 0;
 			entry->ecx = 0;
+			entry->edx = 0;
 		}
 		entry->eax = 0;
-		entry->edx = 0;
 		break;
 	}
 	case 9:
-- 
2.7.4