Add AMD64 micro architecture level support

This commit adds the support for AMD64 micro architecture levels
on Linux.

cpuinfo.go

@@ -23,7 +23,8 @@ import (
 	"github.com/containerd/log"
 )
 
-// Present the ARM instruction set architecture, eg: v7, v8
+// Present the instruction set architecture, eg: v7, v8 for ARM CPU,
+// v3, v4 for AMD64 CPU.
 // Don't use this value directly; call cpuVariant() instead.
 var cpuVariantValue string
 
@@ -33,9 +34,15 @@ func cpuVariant() string {
 	cpuVariantOnce.Do(func() {
 		if isArmArch(runtime.GOARCH) {
 			var err error
-			cpuVariantValue, err = getCPUVariant()
+			cpuVariantValue, err = getArmCPUVariant()
 			if err != nil {
-				log.L.Errorf("Error getCPUVariant for OS %s: %v", runtime.GOOS, err)
+				log.L.Errorf("Error getArmCPUVariant for OS %s: %v", runtime.GOOS, err)
+			}
+		} else if isAmd64Arch(runtime.GOARCH) {
+			var err error
+			cpuVariantValue, err = getAmd64MicroArchLevel()
+			if err != nil {
+				log.L.Errorf("Error getAmd64MicroArchLevel for OS %s: %v", runtime.GOOS, err)
 			}
 		}
 	})

cpuinfo_linux.go

@@ -106,12 +106,12 @@ func getCPUVariantFromArch(arch string) (string, error) {
 	return variant, nil
 }
 
-// getCPUVariant returns cpu variant for ARM
+// getArmCPUVariant returns cpu variant for ARM
 // We first try reading "Cpu architecture" field from /proc/cpuinfo
 // If we can't find it, then fall back using a system call
 // This is to cover running ARM in emulated environment on x86 host as this field in /proc/cpuinfo
 // was not present.
-func getCPUVariant() (string, error) {
+func getArmCPUVariant() (string, error) {
 	variant, err := getCPUInfo("Cpu architecture")
 	if err != nil {
 		if errors.Is(err, errNotFound) {
@@ -158,3 +158,40 @@ func getCPUVariant() (string, error) {
 
 	return variant, nil
 }
+
+func getAmd64MicroArchLevel() (string, error) {
+	flags, err := getCPUInfo("flags")
+	if errors.Is(err, errNotFound) {
+		return "", fmt.Errorf("failure getting CPU flags: %v", err)
+	}
+
+	containsAll := func(set map[string]interface{}, toMatch []string) bool {
+		for _, m := range toMatch {
+			if _, ok := set[m]; !ok {
+				return false
+			}
+		}
+		return true
+	}
+
+	flagSet := map[string]interface{}{}
+	for _, flag := range strings.Split(flags, " ") {
+		flagSet[flag] = true
+	}
+
+	// https://unix.stackexchange.com/questions/631217/how-do-i-check-if-my-cpu-supports-x86-64-v2
+	level := 1
+	if containsAll(flagSet, []string{"lm", "cmov", "cx8", "fpu", "fxsr", "mmx", "syscall", "sse2"}) {
+		level = 1
+	}
+	if level == 1 && containsAll(flagSet, []string{"cx16", "lahf_lm", "popcnt", "sse4_1", "sse4_2", "ssse3"}) {
+		level = 2
+	}
+	if level == 2 && containsAll(flagSet, []string{"avx", "avx2", "bmi1", "bmi2", "f16c", "fma", "abm", "movbe", "xsave"}) {
+		level = 3
+	}
+	if level == 3 && containsAll(flagSet, []string{"avx512f", "avx512bw", "avx512cd", "avx512dq", "avx512vl"}) {
+		level = 4
+	}
+	return fmt.Sprintf("v%d", level), nil
+}

cpuinfo_linux_test.go

@@ -29,7 +29,7 @@ func TestCPUVariant(t *testing.T) {
 
 	variants := []string{"v8", "v7", "v6", "v5", "v4", "v3"}
 
-	p, err := getCPUVariant()
+	p, err := getArmCPUVariant()
 	if err != nil {
 		t.Fatalf("Error getting CPU variant: %v", err)
 		return
@@ -137,3 +137,26 @@ func TestGetCPUVariantFromArch(t *testing.T) {
 
 	}
 }
+
+func TestGetAmd64MicroArchLevel(t *testing.T) {
+	if !isAmd64Arch(runtime.GOARCH) {
+		t.Skip("only relevant on linux/amd64")
+	}
+
+	supportedLevels := []string{"v1", "v2", "v3", "v4"}
+
+	actualLevel, err := getAmd64MicroArchLevel()
+	if err != nil {
+		t.Fatalf("Error getting AMD64 micro architecture level: %v", err)
+		return
+	}
+
+	for _, level := range supportedLevels {
+		if actualLevel == level {
+			t.Logf("got valid micro architecture level as expected: %#v = %#v", actualLevel, level)
+			return
+		}
+	}
+
+	t.Fatalf("could not get valid micro architecture levels as expected: %v", supportedLevels)
+}

cpuinfo_other.go

@@ -23,7 +23,7 @@ import (
 	"runtime"
 )
 
-func getCPUVariant() (string, error) {
+func getArmCPUVariant() (string, error) {
 
 	var variant string
 
@@ -48,8 +48,13 @@ func getCPUVariant() (string, error) {
 			variant = "unknown"
 		}
 	} else {
-		return "", fmt.Errorf("getCPUVariant for OS %s: %v", runtime.GOOS, errNotImplemented)
+		return "", fmt.Errorf("getArmCPUVariant for OS %s: %v", runtime.GOOS, errNotImplemented)
 	}
 
 	return variant, nil
 }
+
+func getAmd64MicroArchLevel() (string, error) {
+	// return v1 on non-Linux platforms
+	return "v1", nil
+}

database.go

@@ -48,6 +48,13 @@ func isArmArch(arch string) bool {
 	return false
 }
 
+// isAmd64Arch returns true if the architecture is AMD64.
+//
+// The arch value should be normalized before being passed to this function.
+func isAmd64Arch(arch string) bool {
+	return arch == "amd64"
+}
+
 // isKnownArch returns true if we know about the architecture.
 //
 // The arch value should be normalized before being passed to this function.

defaults_unix.go

@@ -29,7 +29,7 @@ func DefaultSpec() specs.Platform {
 	return specs.Platform{
 		OS:           runtime.GOOS,
 		Architecture: runtime.GOARCH,
-		// The Variant field will be empty if arch != ARM.
+		// The Variant field will be empty if arch != ARM and AMD64.
 		Variant: cpuVariant(),
 	}
 }

platforms_test.go

@@ -248,6 +248,15 @@ func TestParseSelector(t *testing.T) {
 			},
 			formatted: "linux/amd64",
 		},
+		{
+			input: "Linux/x86_64/v2",
+			expected: specs.Platform{
+				OS:           "linux",
+				Architecture: "amd64",
+				Variant:      "v2",
+			},
+			formatted: "linux/amd64/v2",
+		},
 		{
 			input: "i386",
 			expected: specs.Platform{