On 20/03/2018 15:01, Christopherson, Sean J wrote:
> On Tue, Mar 20, 2018, Dan Carpenter wrote:
>> Hello Sean Christopherson,
>>
>> The patch 2bb8cafea80b: "KVM: vVMX: signal failure for nested VMEntry
>> if emulation_required" from Mar 12, 2018, leads to the following
>> static checker warning:
>>
>> arch/x86/kvm/vmx.c:11199 enter_vmx_non_root_mode()
>> error: uninitialized symbol 'exit_qual'.
>>
>> arch/x86/kvm/vmx.c
>> 11180 static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry)
>> 11181 {
>> 11182 struct vcpu_vmx *vmx = to_vmx(vcpu);
>> 11183 struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
>> 11184 u32 msr_entry_idx;
>> 11185 u32 exit_qual;
>> 11186
>> 11187 enter_guest_mode(vcpu);
>> 11188
>> 11189 if (!(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS))
>> 11190 vmx->nested.vmcs01_debugctl = vmcs_read64(GUEST_IA32_DEBUGCTL);
>> 11191
>> 11192 vmx_switch_vmcs(vcpu, &vmx->nested.vmcs02);
>> 11193 vmx_segment_cache_clear(vmx);
>> 11194
>> 11195 if (prepare_vmcs02(vcpu, vmcs12, from_vmentry, &exit_qual)) {
>>
>> prepare_vmcs02() returns 0 on success and 1 on failure. The patch
>> introduces a new error path which doesn't set *entry_failure_code.
>
> Radim noted this in his initial review. I (incorrectly) assumed Paolo
> had seen the comment prior to queueing the patch.
>
> On Wed, March 14, 2018, Radim Krčmář wrote:
> > 2018-03-12 10:56-0700, Sean Christopherson:
> > > + /*
> > > + * Guest state is invalid and unrestricted guest is disabled,
> > > + * which means L1 attempted VMEntry to L2 with invalid state.
> > > + * Fail the VMEntry.
> > > + */
> > > + if (vmx->emulation_required)
> >
> > We should do "*entry_failure_code = ENTRY_FAIL_DEFAULT" to avoid leaking
> > the L0 stack to L1. With that,
> >
> > Reviewed-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
> >
> > thanks.
>
> Paolo, Radim: do you need me to do anything to help resolve this?
No need, I'll take care of fixing it.
Paolo
>
>> 11196 leave_guest_mode(vcpu);
>> 11197 vmx_switch_vmcs(vcpu, &vmx->vmcs01);
>> 11198 nested_vmx_entry_failure(vcpu, vmcs12,
>> 11199 EXIT_REASON_INVALID_STATE, exit_qual);
>> 11200 return 1;
>> 11201 }
>> 11202
>>
>> regards,
>> dan carpenter
