debug: trying to print out the CPL value, probably doesn't work though

proto/hypervisor.c

@@ -79,6 +79,20 @@ static unsigned char vmxon(unsigned long long pa) {
 }
 
 static int my_init(void) {
+    /*
+     * https://www.sciencedirect.com/topics/computer-science/current-privilege-level
+     */
+    DEBUG_FMT("Querying CS (lowest 2 bits) for CPL\n");
+    unsigned long cs, cpl;
+
+    __asm__ volatile("mov %%cs, %0" : "=r"(cs));
+    cpl = cs & 0x3;
+
+    DEBUG_FMT("CPL level = %lu\n", cpl);
+    if (cpl > 0) {
+        return -1;
+    }
+
     pr_info("Checking VMX support using CPUID\n");
     if (!vmx_support_cpuid()) {
         pr_err("VMX isn't supported\n");
@@ -119,6 +133,9 @@ static int my_init(void) {
     unsigned char vmxon_ret = 0;
 
     if ((vmxon_ret = vmxon(vmxon_region.pa) != 0)) {
+        /*unsigned long vm_err = __rdmsr(0x4400);*/
+        /*pr_err("VM_ERR val = 0x%lx\n", vm_err);*/
+
         kfree(vmxon_region.va);
         __asm__ volatile("vmxoff");
         pr_err("`vmxon` failed with return code %d\n", vmxon_ret);