Re: [PATCH 7/7] KVM: VMX: Introduce test mode related to EPT violation VE

[Paolo Bonzini]

On 5/16/24 01:38, Sean Christopherson wrote:
> On Tue, May 07, 2024, Paolo Bonzini wrote:
> > @@ -5200,6 +5215,9 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
> >   	if (is_invalid_opcode(intr_info))
> >   		return handle_ud(vcpu);
> >   
> > +	if (KVM_BUG_ON(is_ve_fault(intr_info), vcpu->kvm))
> > +		return -EIO;
>
> I've hit this three times now when running KVM-Unit-Tests (I'm pretty sure it's
> the EPT test, unsurprisingly).  And unless I screwed up my testing, I verified it
> still fires with Isaku's fix[*], though I'm suddenly having problems repro'ing.
>
> I'll update tomorrow as to whether I botched my testing of Isaku's fix, or if
> there's another bug lurking.
>
> https://lore.kernel.org/all/20240515173209.GD168153@xxxxxxxxxxxxxxxxxxxxx

I cannot reproduce it on a Skylake (Xeon Gold 5120), with or without 
Isaku's fix, with either ./runtests.sh or your reproducer line.

However I can reproduce it only if eptad=0 and with the following line:

/x86/run x86/vmx.flat -smp 1 -cpu max,host-phys-bits,+vmx -m 2560 \
  -append 'ept_access_test_not_present ept_access_test_read_only'



Paolo