Re: [PATCH] kvm: x86: vmx: avoid returning bool to distinguish success from error

[Chen, Tiejun]

On 2014/11/5 9:43, Chen, Tiejun wrote:
> On 2014/11/5 1:33, Paolo Bonzini wrote:
> > Return a negative error code instead, and WARN() when we should be
> > covering
> > the entire 2-bit space of vmcs_field_type's return value.  For increased
> > robustness, add a BUILD_BUG_ON checking the range of
> > vmcs_field_to_offset.
> >
> > Suggested-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > ---
> >   arch/x86/kvm/vmx.c | 51

[snip]

> > @@ -6576,6 +6581,9 @@ static void copy_shadow_to_vmcs12(struct
> > vcpu_vmx *vmx)
> >           case VMCS_FIELD_TYPE_NATURAL_WIDTH:
> >               field_value = vmcs_readl(field);
> >               break;
> > +        default:
> > +            WARN_ON(1);
> > +            continue;
>
> 'continue' versus 'break'?
>
> Thanks
> Tiejun
>
> >           }
> >           vmcs12_write_any(&vmx->vcpu, field, field_value);
> >       }
> > @@ -6621,6 +6629,9 @@ static void copy_vmcs12_to_shadow(struct
> > vcpu_vmx *vmx)
> >               case VMCS_FIELD_TYPE_NATURAL_WIDTH:
> >                   vmcs_writel(field, (long)field_value);
> >                   break;
> > +            default:
> > +                WARN_ON(1);
> > +                break;
> >               }
> >           }
> >       }
> > @@ -6659,7 +6670,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
> >       /* Decode instruction info and find the field to read */
> >       field = kvm_register_readl(vcpu, (((vmx_instruction_info) >> 28)
> > & 0xf));
> >       /* Read the field, zero-extended to a u64 field_value */
> > -    if (!vmcs12_read_any(vcpu, field, &field_value)) {
> > +    if (vmcs12_read_any(vcpu, field, &field_value) < 0) {
> >           nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
> >           skip_emulated_instruction(vcpu);
> >           return 1;

Looks we're missing another place,

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6601,7 +6601,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
                return 1;
        }

-       if (!vmcs12_write_any(vcpu, field, field_value)) {
+       if (vmcs12_write_any(vcpu, field, field_value) < 0) {
                nested_vmx_failValid(vcpu, 
VMXERR_UNSUPPORTED_VMCS_COMPONENT);
                skip_emulated_instruction(vcpu);
                return 1;
Thanks
Tiejun
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