Add cpuid features block (EAX=07H,ECX=0):EDX.

This block holds information about whether AMX is enabled or not,
which is important for CPUs that support it due to the fact that
the fpstate buffer becomes dynamically sized, and the cpuid value
reported for extended state size assumes that AMX is enabled for
any given process.

PiperOrigin-RevId: 598941137

pkg/cpuid/features_amd64.go

@@ -127,6 +127,14 @@ func (f Feature) set(s ChangeableSet, on bool) {
 			}
 		}
 		s.Set(In{Eax: uint32(extendedFeatures)}, out)
+	case 7:
+		out := s.Query(In{Eax: uint32(extendedFeatureInfo)})
+		if on {
+			out.Edx |= f.bit()
+		} else {
+			out.Edx &^= f.bit()
+		}
+		s.Set(In{Eax: uint32(extendedFeatureInfo)}, out)
 	}
 }
 
@@ -170,6 +178,9 @@ func (f Feature) check(fs FeatureSet) bool {
 			return ((dx &^ block6DuplicateMask) & f.bit()) != 0
 		}
 		return false
+	case 7:
+		_, _, _, dx := fs.query(extendedFeatureInfo)
+		return (dx & f.bit()) != 0
 	default:
 		return false
 	}
@@ -389,6 +400,43 @@ const (
 	X86Feature3DNOW    Feature = 6*32 + 31
 )
 
+// Block 7 constants are the extended features bits in
+// CPUID.(EAX=07H,ECX=0):EDX.
+const (
+	_ Feature = 7*32 + iota // edx bit 0 is reserved.
+	_                       // edx bit 1 is reserved.
+	X86FeatureAVX512_4VNNIW
+	X86FeatureAVX512_4FMAPS
+	X86FeatureFSRM
+	_ // edx bit 5 is not used in Linux.
+	_ // edx bit 6 is reserved.
+	_ // edx bit 7 is reserved.
+	X86FeatureAVX512_VP2INTERSECT
+	X86FeatureSRBDS_CTRL
+	X86FeatureMD_CLEAR
+	X86FeatureRTM_ALWAYS_ABORT
+	_ // edx bit 12 is reserved.
+	X86FeatureTSX_FORCE_ABORT
+	X86FeatureSERIALIZE
+	X86FeatureHYBRID_CPU
+	X86FeatureTSXLDTRK
+	_ // edx bit 17 is reserved.
+	X86FeaturePCONFIG
+	X86FeatureARCH_LBR
+	X86FeatureIBT
+	_ // edx bit 21 is reserved.
+	X86FeatureAMX_BF16
+	X86FeatureAVX512_FP16
+	X86FeatureAMX_TILE
+	X86FeatureAMX_INT8
+	X86FeatureSPEC_CTRL
+	X86FeatureINTEL_STIBP
+	X86FeatureFLUSH_L1D
+	X86FeatureARCH_CAPABILITIES
+	X86FeatureCORE_CAPABILITIES
+	X86FeatureSPEC_CTRL_SSBD
+)
+
 // These are the extended floating point state features. They are used to
 // enumerate floating point features in XCR0, XSTATE_BV, etc.
 const (
@@ -569,6 +617,32 @@ var allFeatures = map[Feature]allFeatureInfo{
 	X86FeatureLM:       {"lm", true},
 	X86Feature3DNOWEXT: {"3dnowext", true},
 	X86Feature3DNOW:    {"3dnow", true},
+
+	// Block 7.
+	X86FeatureAVX512_4VNNIW:       {"avx512_4vnniw", true},
+	X86FeatureAVX512_4FMAPS:       {"avx512_4fmaps", true},
+	X86FeatureFSRM:                {"fsrm", true},
+	X86FeatureAVX512_VP2INTERSECT: {"avx512_vp2intersect", true},
+	X86FeatureSRBDS_CTRL:          {"srbds_ctrl", false},
+	X86FeatureMD_CLEAR:            {"md_clear", true},
+	X86FeatureRTM_ALWAYS_ABORT:    {"rtm_always_abort", false},
+	X86FeatureTSX_FORCE_ABORT:     {"tsx_force_abort", false},
+	X86FeatureSERIALIZE:           {"serialize", true},
+	X86FeatureHYBRID_CPU:          {"hybrid_cpu", false},
+	X86FeatureTSXLDTRK:            {"tsxldtrk", true},
+	X86FeaturePCONFIG:             {"pconfig", true},
+	X86FeatureARCH_LBR:            {"arch_lbr", true},
+	X86FeatureIBT:                 {"ibt", true},
+	X86FeatureAMX_BF16:            {"amx_bf16", true},
+	X86FeatureAVX512_FP16:         {"avx512_fp16", true},
+	X86FeatureAMX_TILE:            {"amx_tile", true},
+	X86FeatureAMX_INT8:            {"amx_int8", true},
+	X86FeatureSPEC_CTRL:           {"spec_ctrl", false},
+	X86FeatureINTEL_STIBP:         {"intel_stibp", false},
+	X86FeatureFLUSH_L1D:           {"flush_l1d", true},
+	X86FeatureARCH_CAPABILITIES:   {"arch_capabilities", true},
+	X86FeatureCORE_CAPABILITIES:   {"core_capabilities", false},
+	X86FeatureSPEC_CTRL_SSBD:      {"spec_ctrl_ssbd", false},
 }
 
 // linuxBlockOrder defines the order in which linux organizes the feature
@@ -576,7 +650,7 @@ var allFeatures = map[Feature]allFeatureInfo{
 // which doesn't match well here, so for the /proc/cpuinfo generation we simply
 // re-map the blocks to Linux's ordering and then go through the bits in each
 // block.
-var linuxBlockOrder = []block{1, 6, 0, 5, 2, 4, 3}
+var linuxBlockOrder = []block{1, 6, 0, 5, 2, 4, 3, 7}
 
 func archFlagOrder(fn func(Feature)) {
 	for _, b := range linuxBlockOrder {