From 2978e6b75fb7f6fc4576a19495eaee277acdd74d Mon Sep 17 00:00:00 2001
From: "iliya.saroukha" <iliya.saroukhanian@etu.hesge.ch>
Date: Tue, 10 Dec 2024 15:20:30 +0100
Subject: [PATCH] debug: trying to print out the CPL value, probably doesn't
work though
---
proto/hypervisor.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/proto/hypervisor.c b/proto/hypervisor.c
index 2f262fa..3984043 100644
--- a/proto/hypervisor.c
+++ b/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);
--
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