RE: [PATCH V4 3/3] x86/efi: Introduce EFI_PAGE_FAULT_HANDLER

[Prakhya, Sai Praneeth]

> > There may exist some buggy UEFI firmware implementations that might
> > access efi regions other than EFI_RUNTIME_SERVICES_<CODE/DATA> even
> > after the kernel has assumed control of the platform. This violates
> > UEFI specification.
> >
> > If selected, this debug option will print a warning message if the
> > UEFI firmware tries to access any memory region which it shouldn't.
> > Along with the warning, the efi page fault handler will also try to
> > recover from the page fault triggered by the firmware so that the
> > machine doesn't hang.
> 
> Why make this optional?

I made it as a config option in RFC because the page fault handler was 
complicated and touching many parts (it had lots of code change and I didn't want 
to break any existing functionality). Now that it's simple, I don't think we need 
the config option.

Without efi page fault handler, any page fault caused by firmware should panic 
kernel but with this patch I think we are just improving existing condition (ideally).

So, if Thomas, Ingo, Andy, Ard and Boris are ok.. I will make it as default (i.e. without
config).

Regards,
Sai