Re: [PATCH v3 02/22] include/xen/slr-table.h: Secure Launch Resource Table definitions

[Sergii Dmytruk <sergii.dmytruk@xxxxxxxxx>]

On Tue, Jul 08, 2025 at 08:52:36AM +0200, Jan Beulich wrote:
> On 07.07.2025 19:31, Sergii Dmytruk wrote:
> > On Mon, Jul 07, 2025 at 10:29:46AM +0200, Jan Beulich wrote:
> >>>> ... then isn't used right here, instead requiring a cast somewhere 
> >>>> (presumably,
> >>>> as code using this isn't visible in this patch).
> >>>
> >>> As was mentioned earlier: because size of a pointer between Xen and a
> >>> bootloader doesn't necessarily match.  What you're proposing can break
> >>> under certain conditions.
> >>
> >> But the header isn't shared with a bootloader's code base. It's private to
> >> Xen.
> >
> > Yes, but sources of Xen be compiled with different size of a pointer
> > which messes up the interpretation of the data.  I tried using
> > BUILD_BUG_ON() to enforce the pointer is 64-bit and early code stopped
> > compiling.  The structures must not vary like that.
>
> Hmm. Does early code actually need to have this struct exposed to it?
>
> Jan

It doesn't use this particular structure, but it uses some other ones in
the header (also SLRT entries, but of different types).  Making a
separate header just to get rid of a cast doesn't seem to be worth it.

Regards