Re: [PATCH 07/11] treewide: Replace the use of mem_encrypt_active() with prot_guest_has()

[Tom Lendacky]

On 8/12/21 5:07 AM, Kirill A. Shutemov wrote:
> On Wed, Aug 11, 2021 at 10:52:55AM -0500, Tom Lendacky wrote:
> > On 8/11/21 7:19 AM, Kirill A. Shutemov wrote:
> > > On Tue, Aug 10, 2021 at 02:48:54PM -0500, Tom Lendacky wrote:
> > > > On 8/10/21 1:45 PM, Kuppuswamy, Sathyanarayanan wrote:
...
> > > Looking at code agains, now I *think* the reason is accessing a global
> > > variable from __startup_64() inside TDX version of prot_guest_has().
> > >
> > > __startup_64() is special. If you access any global variable you need to
> > > use fixup_pointer(). See comment before __startup_64().
> > >
> > > I'm not sure how you get away with accessing sme_me_mask directly from
> > > there. Any clues? Maybe just a luck and complier generates code just right
> > > for your case, I donno.
> >
> > Hmm... yeah, could be that the compiler is using rip-relative addressing
> > for it because it lives in the .data section?
>
> I guess. It has to be fixed. It may break with complier upgrade or any
> random change around the code.

I'll look at doing that separate from this series.

> BTW, does it work with clang for you?

I haven't tried with clang, I'll check on that.

Thanks,
Tom

>