https://bugzilla.kernel.org/show_bug.cgi?id=106621 Bug ID: 106621 Summary: Failure to install Hyper-V role on nested KVM guest Product: Virtualization Version: unspecified Kernel Version: 4.3.0-rc7 Hardware: x86-64 OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: kvm Assignee: virtualization_kvm@xxxxxxxxxxxxxxxxxxxx Reporter: Rainmaker52@xxxxxxxxx Regression: No When installing the Hyper-V role on a Windows guest (tried 2008 R2, 2012 R2 and 2016 TP3), the Windows installer refuses to install because of the error "Hyper-V cannot be installed because virtualization support is not enabled in the BIOS." This is because the MSR 0x3a is initialized to "0". When VMX is activated on the guest CPU, the 0x3a register should return "5". The following code patch (may be a bit of an overstatement) returns "5" if VMX is set on the guest CPU, thereby reporting to the guest that visualization is enabled in the BIOS. --- a/arch/x86/kvm/vmx.c 2015-10-25 02:39:47.000000000 +0100 +++ b/arch/x86/kvm/vmx.c 2015-10-26 13:35:51.894700786 +0100 @@ -2661,7 +2661,12 @@ case MSR_IA32_FEATURE_CONTROL: if (!nested_vmx_allowed(vcpu)) return 1; - msr_info->data = to_vmx(vcpu)->nested.msr_ia32_feature_control; + if (nested_vmx_allowed(vcpu)) { + //Set all 3 bits in 0x3a + msr_info->data = 5; + } else { + msr_info->data = to_vmx(vcpu)->nested.msr_ia32_feature_control; + } break; case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC: if (!nested_vmx_allowed(vcpu)) This, together with "-cpu host,-hypervisor,+vmx will allow Hyper-V to be installed. It will however not allow to start these Virtual Machines. -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
