6 files changed, 38 insertions, 4 deletions
diff --git a/pkg/cpuid/cpuid.go b/pkg/cpuid/cpuid.go
index 69eeb7528..4d5e062a8 100644
--- a/pkg/cpuid/cpuid.go
+++ b/pkg/cpuid/cpuid.go
@@ -37,6 +37,14 @@ package cpuid
 // arch/arm64/include/uapi/asm/hwcap.h
 type Feature int
 
+// HostFeatureSet returns a FeatureSet that matches that of the host machine.
+// Callers must not mutate the returned FeatureSet.
+func HostFeatureSet() *FeatureSet {
+	return hostFeatureSet
+}
+
+var hostFeatureSet = getHostFeatureSet()
+
 // ErrIncompatible is returned by FeatureSet.HostCompatible if fs is not a
 // subset of the host feature set.
 type ErrIncompatible struct {
diff --git a/pkg/cpuid/cpuid_arm64.go b/pkg/cpuid/cpuid_arm64.go
index 98c6ec62f..04645aed5 100644
--- a/pkg/cpuid/cpuid_arm64.go
+++ b/pkg/cpuid/cpuid_arm64.go
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build arm64
 // +build arm64
 
 package cpuid
@@ -229,6 +230,16 @@ type FeatureSet struct {
 	CPURevision uint8
 }
 
+// Clone returns a copy of fs.
+func (fs *FeatureSet) Clone() *FeatureSet {
+	fs2 := *fs
+	fs2.Set = make(map[Feature]bool)
+	for f, b := range fs.Set {
+		fs2.Set[f] = b
+	}
+	return &fs2
+}
+
 // CheckHostCompatible returns nil if fs is a subset of the host feature set.
 // Noop on arm64.
 func (fs *FeatureSet) CheckHostCompatible() error {
@@ -291,9 +302,9 @@ func (fs FeatureSet) WriteCPUInfoTo(cpu uint, b *bytes.Buffer) {
 	fmt.Fprintln(b, "") // The /proc/cpuinfo file ends with an extra newline.
 }
 
-// HostFeatureSet uses hwCap to get host values and construct a feature set
+// getHostFeatureSet uses hwCap to get host values and construct a feature set
 // that matches that of the host machine.
-func HostFeatureSet() *FeatureSet {
+func getHostFeatureSet() *FeatureSet {
 	s := make(map[Feature]bool)
 
 	for f := range arm64FeatureStrings {
diff --git a/pkg/cpuid/cpuid_arm64_test.go b/pkg/cpuid/cpuid_arm64_test.go
index a34f67779..16b1c064a 100644
--- a/pkg/cpuid/cpuid_arm64_test.go
+++ b/pkg/cpuid/cpuid_arm64_test.go
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build arm64
 // +build arm64
 
 package cpuid
diff --git a/pkg/cpuid/cpuid_parse_x86_test.go b/pkg/cpuid/cpuid_parse_x86_test.go
index d60fdb550..36dd20552 100644
--- a/pkg/cpuid/cpuid_parse_x86_test.go
+++ b/pkg/cpuid/cpuid_parse_x86_test.go
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build 386 || amd64
 // +build 386 amd64
 
 package cpuid
diff --git a/pkg/cpuid/cpuid_x86.go b/pkg/cpuid/cpuid_x86.go
index 392711e8f..a92d32d74 100644
--- a/pkg/cpuid/cpuid_x86.go
+++ b/pkg/cpuid/cpuid_x86.go
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build 386 || amd64
 // +build 386 amd64
 
 package cpuid
@@ -626,6 +627,17 @@ type FeatureSet struct {
 	CacheLine uint32
 }
 
+// Clone returns a copy of fs.
+func (fs *FeatureSet) Clone() *FeatureSet {
+	fs2 := *fs
+	fs2.Set = make(map[Feature]bool)
+	for f, b := range fs.Set {
+		fs2.Set[f] = b
+	}
+	fs2.Caches = append([]Cache(nil), fs.Caches...)
+	return &fs2
+}
+
 // FlagsString prints out supported CPU flags. If cpuinfoOnly is true, it is
 // equivalent to the "flags" field in /proc/cpuinfo.
 func (fs *FeatureSet) FlagsString(cpuinfoOnly bool) string {
@@ -960,13 +972,13 @@ func (fs *FeatureSet) UseXsaveopt() bool {
 // HostID executes a native CPUID instruction.
 func HostID(axArg, cxArg uint32) (ax, bx, cx, dx uint32)
 
-// HostFeatureSet uses cpuid to get host values and construct a feature set
+// getHostFeatureSet uses cpuid to get host values and construct a feature set
 // that matches that of the host machine. Note that there are several places
 // where there appear to be some unnecessary assignments between register names
 // (ax, bx, cx, or dx) and featureBlockN variables. This is to explicitly show
 // where the different feature blocks come from, to make the code easier to
 // inspect and read.
-func HostFeatureSet() *FeatureSet {
+func getHostFeatureSet() *FeatureSet {
 	// eax=0 gets max supported feature and vendor ID.
 	_, bx, cx, dx := HostID(0, 0)
 	vendorID := vendorIDFromRegs(bx, cx, dx)
diff --git a/pkg/cpuid/cpuid_x86_test.go b/pkg/cpuid/cpuid_x86_test.go
index bacf345c8..92a2d9f81 100644
--- a/pkg/cpuid/cpuid_x86_test.go
+++ b/pkg/cpuid/cpuid_x86_test.go
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build 386 || amd64
 // +build 386 amd64
 
 package cpuid