Re: [PATCH][4.17] EFI: don't convert memory marked for runtime use to ordinary RAM

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 06/10/2022 15:11, Jan Beulich wrote:
> > ... the space cannot become ordinary RAM, then such a precaution
> > wouldn't be necessary. After all hiding EfiACPIReclaimMemory from
> > Dom0 just because it can't be mapped WB wouldn't be very nice
> > either. I guess I'll submit v2 with this part of the change left
> > as it was.
> And while already in the process of committing the patch I came to
> realize that if the WB conditional isn't supposed to move, isn't
> the change done for Arm then wrong as well? Shouldn't it then be
>
>          if ( !(desc_ptr->Attribute & EFI_MEMORY_RUNTIME) &&
>               (desc_ptr->Attribute & EFI_MEMORY_WB) &&
>               (desc_ptr->Type == EfiConventionalMemory ||
>               ...
>
> leaving the EfiACPIReclaimMemory case entirely unaffected by the
> change?
IIUC, the concern is the region EfiACPIReclaimMemory could have the 
attribute EFI_MEMORY_RUNTIME. Is that correct?
Given that the memory is reclaimable, I am not sure why it can also have 
this atribute set (to me it means the opposite). But I guess for 
hardening purpose it would be better to use the version you just suggested.
Bertrand, Stefano, what do you think?

Cheers,

--
Julien Grall