Re: [PATCH 4/8] x86/traps: Demand-populate PASID MSR via #GP

[Luck, Tony]

On Wed, Sep 22, 2021 at 11:07:22PM +0200, Peter Zijlstra wrote:
> On Mon, Sep 20, 2021 at 07:23:45PM +0000, Fenghua Yu wrote:
> > @@ -538,6 +547,9 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
> >  
> >  	cond_local_irq_enable(regs);
> >  
> > +	if (user_mode(regs) && fixup_pasid_exception())
> > +		goto exit;
> > +

> So you're eating any random #GP that might or might not be PASID
> related. And all that witout a comment... Enlighten?

This is moderately well commented inside the fixup_pasid_exception()
function. Another copy of the comments here at the call-site seems
overkill.

Would it help to change the name to try_fixup_pasid_exception()
to make it clearer that this is just a heuristic that may or may
not fix this particular #GP?

-Tony