todo: need to understand thoroughly the code added

proto/hypervisor.c

@@ -2,12 +2,54 @@
 #include <linux/init.h>   /* Needed for the macros */
 #include <linux/module.h> /* Needed by all modules */
 
+#define FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX (1 << 2)
+#define FEATURE_CONTROL_LOCKED (1 << 0)
+#define MSR_IA32_FEATURE_CONTROL 0x0000003a
+
 /*asm ( assembler template*/
 /*    : output operands                   (optional)*/
 /*    : input operands                    (optional)*/
 /*    : clobbered registers list          (optional)*/
 /*    );*/
 
+static bool getVmxOperation(void) {
+    /*
+     * Configure IA32_FEATURE_CONTROL MSR to allow VMXON:
+     *  Bit 0: Lock bit. If clear, VMXON causes a #GP.
+     *  Bit 2: Enables VMXON outside of SMX operation. If clear, VMXON
+     *    outside of SMX causes a #GP.
+     */
+
+    unsigned long cr0, cr4;
+    unsigned long long required, feature_control;
+    unsigned long low1 = 0;
+    required = FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
+    required |= FEATURE_CONTROL_LOCKED;
+    feature_control = __rdmsr(MSR_IA32_FEATURE_CONTROL);
+    printk(KERN_INFO "RDMS output is %ld\n", (long)feature_control);
+
+    if ((feature_control & required) != required) {
+        wrmsr(MSR_IA32_FEATURE_CONTROL, feature_control | required, low1);
+    }
+
+    /*
+     * Ensure bits in CR0 and CR4 are valid in VMX operation:
+     * - Bit X is 1 in _FIXED0: bit X is fixed to 1 in CRx.
+     * - Bit X is 0 in _FIXED1: bit X is fixed to 0 in CRx.
+     */
+    __asm__ volatile("mov %%cr0, %0" : "=r"(cr0) : : "memory");
+    cr0 &= __rdmsr(MSR_IA32_VMX_CR0_FIXED1);
+    cr0 |= __rdmsr(MSR_IA32_VMX_CR0_FIXED0);
+    __asm__ volatile("mov %0, %%cr0" : : "r"(cr0) : "memory");
+
+    __asm__ volatile("mov %%cr4, %0" : "=r"(cr4) : : "memory");
+    cr4 &= __rdmsr(MSR_IA32_VMX_CR4_FIXED1);
+    cr4 |= __rdmsr(MSR_IA32_VMX_CR4_FIXED0);
+    __asm__ volatile("mov %0, %%cr4" : : "r"(cr4) : "memory");
+
+    return true;
+}
+
 static void enable_vmx(void) {
     unsigned long cr4;
 
@@ -38,6 +80,11 @@ static int my_init(void) {
 
     printk(KERN_INFO "VMX has been successfully enabled!\n");
 
+    if (!getVmxOperation()) {
+        printk(KERN_INFO "VMX operation couldn't correctly setup\n");
+        return -1;
+    }
+
     return 0;
 }