linux-kernel - [PATCH v3 17/22] kvm: x86: Add CPUID support for Intel AMX

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Date:   Wed, 22 Dec 2021 04:40:47 -0800
From:   Jing Liu <jing2.liu@...el.com>
To:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, pbonzini@...hat.com, corbet@....net,
        shuah@...nel.org
Cc:     seanjc@...gle.com, jun.nakajima@...el.com, kevin.tian@...el.com,
        jing2.liu@...ux.intel.com, jing2.liu@...el.com,
        guang.zeng@...el.com, wei.w.wang@...el.com, yang.zhong@...el.com
Subject: [PATCH v3 17/22] kvm: x86: Add CPUID support for Intel AMX

Extend CPUID emulation to support XFD, AMX_TILE, AMX_INT8 and
AMX_BF16. Adding those bits into kvm_cpu_caps finally activates all
previous logics in this series.

Signed-off-by: Yang Zhong <yang.zhong@...el.com>
Signed-off-by: Jing Liu <jing2.liu@...el.com>
---
 arch/x86/include/asm/cpufeatures.h |  2 ++
 arch/x86/kvm/cpuid.c               | 25 +++++++++++++++++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index d5b5f2ab87a0..da872b6f8d8b 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -299,7 +299,9 @@
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
 #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI instructions */
 #define X86_FEATURE_AVX512_BF16		(12*32+ 5) /* AVX512 BFLOAT16 instructions */
+#define X86_FEATURE_AMX_BF16		(18*32+22) /* AMX bf16 Support */
 #define X86_FEATURE_AMX_TILE		(18*32+24) /* AMX tile Support */
+#define X86_FEATURE_AMX_INT8		(18*32+25) /* AMX int8 Support */
 
 /* 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 eb5a5070accb..1d694ead374e 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -515,7 +515,8 @@ void kvm_set_cpu_caps(void)
 		F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
 		F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) |
 		F(MD_CLEAR) | F(AVX512_VP2INTERSECT) | F(FSRM) |
-		F(SERIALIZE) | F(TSXLDTRK) | F(AVX512_FP16)
+		F(SERIALIZE) | F(TSXLDTRK) | F(AVX512_FP16) |
+		F(AMX_TILE) | F(AMX_INT8) | F(AMX_BF16)
 	);
 
 	/* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */
@@ -534,7 +535,7 @@ void kvm_set_cpu_caps(void)
 	);
 
 	kvm_cpu_cap_mask(CPUID_D_1_EAX,
-		F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES)
+		F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES) | F(XFD)
 	);
 
 	kvm_cpu_cap_init_scattered(CPUID_12_EAX,
@@ -660,6 +661,8 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array,
 	case 0x14:
 	case 0x17:
 	case 0x18:
+	case 0x1d:
+	case 0x1e:
 	case 0x1f:
 	case 0x8000001d:
 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
@@ -932,6 +935,24 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 				goto out;
 		}
 		break;
+	/* Intel AMX TILE */
+	case 0x1d:
+		if (!kvm_cpu_cap_has(X86_FEATURE_AMX_TILE)) {
+			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
+			break;
+		}
+
+		for (i = 1, max_idx = entry->eax; i <= max_idx; ++i) {
+			if (!do_host_cpuid(array, function, i))
+				goto out;
+		}
+		break;
+	case 0x1e: /* TMUL information */
+		if (!kvm_cpu_cap_has(X86_FEATURE_AMX_TILE)) {
+			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
+			break;
+		}
+		break;
 	case KVM_CPUID_SIGNATURE: {
 		const u32 *sigptr = (const u32 *)KVM_SIGNATURE;
 		entry->eax = KVM_CPUID_FEATURES;
-- 
2.27.0