Re: [PATCH v15 16/23] x86/sgx: Enumerate and track EPC sections

[Jarkko Sakkinen]

On Sat, Nov 03, 2018 at 03:22:34PM +0200, Andy Shevchenko wrote:
> On Sat, Nov 3, 2018 at 1:17 AM Jarkko Sakkinen
> <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote:
> >
> > From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> >
> > Enumerate Enclave Page Cache (EPC) sections via CPUID and add the data
> > structures necessary to track EPC pages so that they can be allocated,
> > freed and managed.  As a system may have multiple EPC sections, invoke
> > CPUID on SGX sub-leafs until an invalid leaf is encountered.
> >
> > On NUMA systems, a node can have at most one bank. A bank can be at
> > most part of two nodes.  SGX supports both nodes with a single memory
> > controller and also sub-cluster nodes with severals memory controllers
> > on a single die.
> >
> > For simplicity, support a maximum of eight EPC sections.  Current
> > client hardware supports only a single section, while upcoming server
> > hardware will support at most eight sections.  Bounding the number of
> > sections also allows the section ID to be embedded along with a page's
> > offset in a single unsigned long, enabling easy retrieval of both the
> > VA and PA for a given page.
> 
> > +       iounmap(section->va);
> 
> > +       section->va = ioremap_cache(addr, size);
> > +       if (!section->va)
> > +               return -ENOMEM;
> 
> I forgot if it's a place in code on which we discussed ioremap() vs.
> memremap() call.
> And I forgot why the conclusion is to leave ioremap().
> 
> Sorry, if I'm mistaken.

Thanks for pointing this out. It very well might I have either

1. forgotten to do the switch.
2. had some open about it that I forgot to ask.

Anyway, I'll check this and at minimum document the reason to the
change log if there is one to keep the ioremap().

/Jarkko