Re: [PATCH 2/5] KVM: TDX: Exit with MEMORY_FAULT on unexpected pending S-EPT Violation

[Edgecombe, Rick P]

On Tue, 2025-07-29 at 16:08 -0700, Sean Christopherson wrote:
> > If userspace runs the vCPU again then an EPT violation gets triggered again,
> > which again gets kicked out to userspace. The new check will prevent it from
> > getting into the fault handler, right?
> 
> Yes?  But I'm confused about why you mentioned vm_dead, and why you're calling
> this a "new check".  This effectively does two things: drops kvm_vm_dead() and
> switches from EOI => EFAULT.  _If_ setting vm_dead was necessary, then we have
> a
> problem.
> 
> I assume by "The vm_dead was added" you really mean "forcing an exit to
> userspace",
> and that kvm_vm_dead()+EIO was a somewhat arbitrary way of forcing an exit?

Sorry, yes vm_dead prevents an EPT violation loop but not the KVM_BUG_ON(). The
whole if clause prevents the KVM_BUG_ON(). Your patch prevents the ept violation
loop in a better way.