wip: reading the values of cr0 and cr4 and their respective VMX MSRs

proto/hypervisor.c

+#include "asm/cpuid.h"
 #include "asm/msr.h"
+#include "asm/paravirt.h"
 #include "linux/kern_levels.h"
 #include "linux/printk.h"
 #include <linux/init.h>   /* Needed for the macros */
 #include <linux/module.h> /* Needed by all modules */
 
-#define IA32_FEATURE_CONTROL_LOCK_BIT (1 << 0)
-#define IA32_FEATURE_CONTROL_VMXON_IN_SMX (1 << 1)
-#define IA32_FEATURE_CONTROL_VMXON_OUTSIDE_SMX (1 << 2)
+#define IA32_FEATURE_CONTROL_LOCK_BIT (1UL << 0)
+#define IA32_FEATURE_CONTROL_VMXON_IN_SMX (1UL << 1)
+#define IA32_FEATURE_CONTROL_VMXON_OUTSIDE_SMX (1UL << 2)
 #define IA32_FEATURE_CONTROL_MSR (0x3a)
 
+// Appendix 8 p. 4'592 of Intel SDM
+#define IA32_VMX_CR0_FIXED0 (0x486)
+#define IA32_VMX_CR0_FIXED1 (0x487)
+#define IA32_VMX_CR4_FIXED0 (0x488)
+#define IA32_VMX_CR4_FIXED1 (0x489)
+
+#define CR0_PE (1UL << 0)
+#define CR0_NE (1UL << 5)
+#define CR0_PG (1UL << 31)
+
 /*asm ( assembler template*/
 /*    : output operands                   (optional)*/
 /*    : input operands                    (optional)*/
@@ -24,11 +36,10 @@ static void cr4_enable_vmx(void) {
 }
 
 static bool vmx_supported(void) {
-    int ecx;
-
-    __asm__ volatile("mov $1, %rax");
-    __asm__ volatile("cpuid");
-    __asm__ volatile("mov %%ecx , %0\n\t" : "=r"(ecx));
+    unsigned int ecx = cpuid_ecx(1);
+    /*__asm__ volatile("mov $1, %rax");*/
+    /*__asm__ volatile("cpuid");*/
+    /*__asm__ volatile("mov %%ecx , %0\n\t" : "=r"(ecx));*/
 
     return (ecx >> 5) & 1;
 }
@@ -52,6 +63,24 @@ static bool ia32_feature_control_flags(void) {
     return true;
 }
 
+static void reading_cr_msr(void) {
+    unsigned long long cr0, cr4;
+
+    __asm__ volatile("mov %%cr0, %0" : "=r"(cr0));
+    __asm__ volatile("mov %%cr4, %0" : "=r"(cr4));
+
+    pr_debug("CR0 = 0x%llx\n", cr0);
+    pr_debug("CR4 = 0x%llx\n\n", cr4);
+
+    /*unsigned long cr0_fixed0 = __rdmsr(IA32_VMX_CR0_FIXED0);*/
+    /*unsigned long cr0_fixed1 = __rdmsr(IA32_VMX_CR0_FIXED1);*/
+
+    pr_debug(KERN_INFO "CR0_FIXED0 = 0x%llx\n", __rdmsr(IA32_VMX_CR0_FIXED0));
+    pr_debug(KERN_INFO "CR0_FIXED1 = 0x%llx\n\n", __rdmsr(IA32_VMX_CR0_FIXED1));
+    pr_debug(KERN_INFO "CR4_FIXED0 = 0x%llx\n", __rdmsr(IA32_VMX_CR4_FIXED0));
+    pr_debug(KERN_INFO "CR4_FIXED1 = 0x%llx\n", __rdmsr(IA32_VMX_CR4_FIXED1));
+}
+
 static int my_init(void) {
     if (!vmx_supported()) {
         printk(KERN_INFO "VMX isn't supported\n");
@@ -73,6 +102,8 @@ static int my_init(void) {
 
     printk(KERN_INFO "IA32_FEATURE_CONTROL MSR flags allow virtualization\n");
 
+    reading_cr_msr();
+
     return 0;
 }