Re: [RFC PATCH 4/4] KVM: vmx: add support for emulating UMIP

[Yang Zhang]

On 2016/7/13 17:35, Paolo Bonzini wrote:
> On 13/07/2016 11:21, Yang Zhang wrote:
> > > +static int handle_desc(struct kvm_vcpu *vcpu)
> > > +{
> > > +    WARN_ON(!(vcpu->arch.cr4 & X86_CR4_UMIP));
> >
> > I think WARN_ON is too heavy since a malicious guest may trigger it always.
>
> I missed this---how so?  Setting the bit is under "if ((cr4 &
> X86_CR4_UMIP) && !boot_cpu_has(X86_FEATURE_UMIP))".

Sorry, I consider it under my previous suggestion(setting it 
unconditionally). :(

--
Yang
Alibaba Cloud Computing