NOVA doesn't detect VMX capability when running in KVM

[blitz]

The IA32_FEATURE_CONTROL MSR in KVM is not implemented. See vmx_get_vmx_msr and vmx_set_vmx_msr in the Linux kernel code.

Quick workaround:

diff --git a/src/vmx.cpp b/src/vmx.cpp
index 4835dc1..fcd9a5f 100644
--- a/src/vmx.cpp
+++ b/src/vmx.cpp
@@ -101,7 +101,7 @@ Vmcs::Vmcs (mword esp, mword bmp, mword cr3, uint64 eptp) : rev (basic.revision)

 void Vmcs::init()
 {
-    if (!Cpu::feature (Cpu::FEAT_VMX) || (Msr::read<uint32>(Msr::IA32_FEATURE_CONTROL) & 0x5) != 0x5) {
+    if (!Cpu::feature (Cpu::FEAT_VMX)) {
         Hip::remove (Hip::FEAT_VMX);
         return;
     }

[udosteinberg]

VMXON is spec'd to read IA32_FEATURE_CONTROL MSR (see pseudocode in the SDM), so if KVM is not reading (or not even implementing) that MSR, it's not working according to the specification.

[blitz]

I know. This bug just remembers the workaround for that until it is fixed in kvm.