Code: static int handle_vmptrst(struct kvm_vcpu *vcpu)
{
	unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
	u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
	gva_t vmcs_gva;
	struct x86_exception e;

	if (!nested_vmx_check_permission(vcpu))
		return 1;

 	if (get_vmx_mem_address(vcpu, exit_qualification,
 			vmx_instruction_info, true, &vmcs_gva))
 		return 1;
	/* ok to use *_system, as hardware has verified cpl=0 */
 	if (kvm_write_guest_virt_system(&vcpu->arch.emulate_ctxt, vmcs_gva,
 				 (void *)&to_vmx(vcpu)->nested.current_vmptr,
 				 sizeof(u64), &e)) {
		kvm_inject_page_fault(vcpu, &e);
		return 1;
	}
	nested_vmx_succeed(vcpu);
	return kvm_skip_emulated_instruction(vcpu);
}

Commit Message: 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>
CWE ID: 
static int handle_vmptrst(struct kvm_vcpu *vcpu)
{
	unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
	u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
	gva_t vmcs_gva;
	struct x86_exception e;

	if (!nested_vmx_check_permission(vcpu))
		return 1;

 	if (get_vmx_mem_address(vcpu, exit_qualification,
 			vmx_instruction_info, true, &vmcs_gva))
 		return 1;
	/* *_system ok, nested_vmx_check_permission has verified cpl=0 */
 	if (kvm_write_guest_virt_system(&vcpu->arch.emulate_ctxt, vmcs_gva,
 				 (void *)&to_vmx(vcpu)->nested.current_vmptr,
 				 sizeof(u64), &e)) {
		kvm_inject_page_fault(vcpu, &e);
		return 1;
	}
	nested_vmx_succeed(vcpu);
	return kvm_skip_emulated_instruction(vcpu);
}
