kvm: nVMX: Enforce cpl=0 for VMX instructions

VMX instructions executed inside a L1 VM will always trigger a VM exit
even when executed with cpl 3. This means we must perform the
privilege check in software.

Fixes: 70f3aac964ae("kvm: nVMX: Remove superfluous VMX instruction fault checks")
Cc: stable@vger.kernel.org
Signed-off-by: Felix Wilhelm <fwilhelm@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
static int vmx_pre_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
{
	struct vcpu_vmx *vmx = to_vmx(vcpu);

	vmx->nested.smm.guest_mode = is_guest_mode(vcpu);
	if (vmx->nested.smm.guest_mode)
		nested_vmx_vmexit(vcpu, -1, 0, 0);

	vmx->nested.smm.vmxon = vmx->nested.vmxon;
	vmx->nested.vmxon = false;
	vmx_clear_hlt(vcpu);
	return 0;
}

static int vmx_pre_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
{
	struct vcpu_vmx *vmx = to_vmx(vcpu);

	vmx->nested.smm.guest_mode = is_guest_mode(vcpu);
	if (vmx->nested.smm.guest_mode)
		nested_vmx_vmexit(vcpu, -1, 0, 0);

	vmx->nested.smm.vmxon = vmx->nested.vmxon;
	vmx->nested.vmxon = false;
	vmx_clear_hlt(vcpu);
	return 0;
}
