intel/haswell: add vmx support w/Kconfig option

patch based on VMX support in intel/fsp_model_206ax and intel/model_6fx
tested/verified working on google/panther

Change-Id: I61232fdc2a29c53aa3bea5ea78b2fdc41fd7396a
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: http://review.coreboot.org/6223
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>

src/cpu/intel/haswell/Kconfig

@@ -34,6 +34,10 @@ config SMM_TSEG_SIZE
 	hex
 	default 0x800000
 
+config ENABLE_VMX
+	bool "Enable VMX for virtualization"
+	default n
+
 config IED_REGION_SIZE
 	hex
 	default 0x400000

src/cpu/intel/haswell/haswell_init.c

@@ -150,6 +150,47 @@ static acpi_cstate_t cstate_map[NUM_C_STATES] = {
 	},
 };
 
+static void enable_vmx(void)
+{
+	struct cpuid_result regs;
+	msr_t msr;
+	int enable = IS_ENABLED(CONFIG_ENABLE_VMX);
+
+	regs = cpuid(1);
+	/* Check that the VMX is supported before reading or writing the MSR. */
+	if (!((regs.ecx & CPUID_VMX) || (regs.ecx & CPUID_SMX)))
+		return;
+
+	msr = rdmsr(IA32_FEATURE_CONTROL);
+
+	if (msr.lo & (1 << 0)) {
+		printk(BIOS_ERR, "VMX is locked, so %s will do nothing\n", __func__);
+		/* VMX locked. If we set it again we get an illegal
+		 * instruction
+		 */
+		return;
+	}
+
+	/* The IA32_FEATURE_CONTROL MSR may initialize with random values.
+	 * It must be cleared regardless of VMX config setting.
+	 */
+	msr.hi = msr.lo = 0;
+
+	printk(BIOS_DEBUG, "%s VMX\n", enable ? "Enabling" : "Disabling");
+
+	if (enable) {
+		msr.lo |= (1 << 2);
+		if (regs.ecx & CPUID_SMX)
+			msr.lo |= (1 << 1);
+	}
+
+	wrmsr(IA32_FEATURE_CONTROL, msr);
+
+	msr.lo |= (1 << 0); /* Set lock bit */
+
+	wrmsr(IA32_FEATURE_CONTROL, msr);
+}
+
 /* Convert time in seconds to POWER_LIMIT_1_TIME MSR value */
 static const u8 power_limit_time_sec_to_msr[] = {
 	[0]   = 0x00,
@@ -703,6 +744,9 @@ static void haswell_init(device_t cpu)
 	enable_lapic_tpr();
 	setup_lapic();
 
+	/* Enable virtualization if Kconfig option is set */
+	enable_vmx();
+
 	/* Configure C States */
 	configure_c_states();