[PATCH 3/6] x86: KVM: Enable AVX-IFMA CPUID and expose it to guest

Jiaxi Chen
2022-10-19T08:56:21Z

AVX-IFMA is a new instruction in the latest Intel platform Sierra Forest.
AVX-IFMA packed multiplies unsigned 52-bit integers and add the low/high
52-bit products to Qword Accumulators.

The bit definition:
CPUID.(EAX=7,ECX=1):EAX[bit 23]

This patch enables this CPUID in the kernel feature bits and expose it
to guest OS.

Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/kvm/cpuid.c | 4 ++--
2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 9313240e3cdd..a682f646243f 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -310,6 +310,7 @@
#define X86_FEATURE_AVX512_BF16 (12*32+ 5) /* AVX512 BFLOAT16 instructions */
#define X86_FEATURE_CMPCCXADD (12*32+ 7) /* CMPccXADD instructions */
#define X86_FEATURE_AMX_FP16 (12*32+21) /* AMX fp16 Support */
+#define X86_FEATURE_AVX_IFMA (12*32+23) /* Support for VPMADD52[H,L]UQ */

/* AMD-defined CPU features, CPUID level 0x80000008 (EBX), word 13 */
#define X86_FEATURE_CLZERO (13*32+ 0) /* CLZERO instruction */
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index d983ddb974ba..837bcd1373e5 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -657,8 +657,8 @@ void kvm_set_cpu_caps(void)
kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);

kvm_cpu_cap_mask(CPUID_7_1_EAX,
- F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) | F(AMX_FP16)
- );
+ F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) | F(AMX_FP16) |
+ F(AVX_IFMA));

kvm_cpu_cap_mask(CPUID_D_1_EAX,
F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES) | f_xfd
--
2.27.0