Add VMX detection

Add detection of VMX (Virtual Machine Extensions) support.

Signed-off-by: Manohar Castelino <manohar.r.castelino@intel.com>

Author: mcastelino

README.md

@@ -64,6 +64,7 @@ Package home: https://github.com/klauspost/cpuid
 *  **RDTSCP** (RDTSCP Instruction)
 *  **CX16** (CMPXCHG16B Instruction)
 *  **SGX** (Software Guard Extensions, with activation details)
+*  **VMX** (Virtual Machine Extensions)
 
 ## Performance
 *  **RDTSCP()** Returns current cycle count. Can be used for benchmarking.

cpuid.go

@@ -80,6 +80,7 @@ const (
 	SGX                     // Software Guard Extensions
 	IBPB                    // Indirect Branch Restricted Speculation (IBRS) and Indirect Branch Predictor Barrier (IBPB)
 	STIBP                   // Single Thread Indirect Branch Predictors
+	VMX                     // Virtual Machine Extensions
 
 	// Performance indicators
 	SSE2SLOW // SSE2 is supported, but usually not faster
@@ -137,6 +138,7 @@ var flagNames = map[Flags]string{
 	SGX:         "SGX",         // Software Guard Extensions
 	IBPB:        "IBPB",        // Indirect Branch Restricted Speculation and Indirect Branch Predictor Barrier
 	STIBP:       "STIBP",       // Single Thread Indirect Branch Predictors
+	VMX:         "VMX",         // Virtual Machine Extensions
 
 	// Performance indicators
 	SSE2SLOW: "SSE2SLOW", // SSE2 supported, but usually not faster
@@ -223,6 +225,11 @@ func (c CPUInfo) Amd3dnowExt() bool {
 	return c.Features&AMD3DNOWEXT != 0
 }
 
+// VMX indicates support of VMX
+func (c CPUInfo) VMX() bool {
+	return c.Features&VMX != 0
+}
+
 // MMX indicates support of MMX instructions
 func (c CPUInfo) MMX() bool {
 	return c.Features&MMX != 0
@@ -820,6 +827,9 @@ func support() Flags {
 	if (c & 1) != 0 {
 		rval |= SSE3
 	}
+	if (c & (1 << 5)) != 0 {
+		rval |= VMX
+	}
 	if (c & 0x00000200) != 0 {
 		rval |= SSSE3
 	}

cpuid_test.go

@@ -114,6 +114,16 @@ func TestAmd3dnowExt(t *testing.T) {
 	t.Log("AMD3DNOWEXT Support:", got)
 }
 
+// TestVMX tests VMX() function
+func TestVMX(t *testing.T) {
+	got := CPU.VMX()
+	expected := CPU.Features&VMX == VMX
+	if got != expected {
+		t.Fatalf("VMX: expected %v, got %v", expected, got)
+	}
+	t.Log("VMX Support:", got)
+}
+
 // TestMMX tests MMX() function
 func TestMMX(t *testing.T) {
 	got := CPU.MMX()