Re: [PATCH] x86_64/efi: Mapping Boot and Runtime EFI memory regions to different starting virtual address

[Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>]

On Thu, 30 Jul, at 10:03:23AM, Borislav Petkov wrote:
> On Thu, Jul 30, 2015 at 12:53:42AM -0700, H. Peter Anvin wrote:
> > This changelog is at least partially incomprehensive. It also seems
> > more than a bit aggressive to expect that 1 GB will be sufficient
> > forever.
> 
> Right, before we do anything, I'd like for us to figure out first why
> this is a problem all of a sudden. And why should we even keep boot
> code/data, if it is fair game, once runtime services get enabled.
> 
> Matt, can you please chime in first before we even talk about a
> solution...

Yeah, I do not understand the issue properly.

Why do we care about EfiBoot* regions after hibernate? Surely we've
already freed those regions in efi_free_boot_services() during boot and
nobody should be touching them again? If the firmware does, that's a
whole new bug we've never encountered before.

And we obviously can't allow the runtime regions to move around during
hibernate/resume because we've already informed the firmware where those
regions live during SetVirtualAddressMap() at boot.

I admit that I haven't looked at the hibernate code paths. Let me go do
that now.

-- 
Matt Fleming, Intel Open Source Technology Center