Re: [PATCH 3/4] KVM: x86: WARN and reject loading KVM if NX is supported but not enabled

[Paolo Bonzini]

On 07/07/21 14:09, Naresh Kamboju wrote:
> On Fri, 25 Jun 2021 at 14:35, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> > On 25/06/21 00:33, Sean Christopherson wrote:
> > > On Tue, Jun 15, 2021, Sean Christopherson wrote:
> > > > WARN if NX is reported as supported but not enabled in EFER.  All flavors
> > > > of the kernel, including non-PAE 32-bit kernels, set EFER.NX=1 if NX is
> > > > supported, even if NX usage is disable via kernel command line.
> > >
> > > Ugh, I misread .Ldefault_entry in head_32.S, it skips over the entire EFER code
> > > if PAE=0.  Apparently I didn't test this with non-PAE paging and EPT?
> > >
> > > Paolo, I'll send a revert since it's in kvm/next, but even better would be if
> > > you can drop the patch :-)  Lucky for me you didn't pick up patch 4/4 that
> > > depends on this...
> > >
> > > I'll revisit this mess in a few weeks.
> >
> > Rather, let's keep this, see if anyone complains and possibly add a
> > "depends on X86_PAE || X86_64" to KVM.
>
> [ please ignore if this is already reported ]
>
> The following kernel warning noticed while booting linus master branch and
> Linux next 20210707 tag on i386 kernel booting on x86_64 machine.

Ok, so the "depends on" is needed.  Let's add it, I'm getting back to 
KVM work and will send the patch today or tomorrow.

Paolo