Re: [PATCHv7 15/19] x86/mm: Replace compile-time checks for 5-level with runtime-time

[Ingo Molnar]

* Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> wrote:

> This patch converts the of CONFIG_X86_5LEVEL check to runtime checks for
> p4d folding.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/mm/fault.c            |  2 +-
>  arch/x86/mm/ident_map.c        |  2 +-
>  arch/x86/mm/init_64.c          | 30 ++++++++++++++++++------------
>  arch/x86/mm/kasan_init_64.c    | 12 ++++++------
>  arch/x86/mm/kaslr.c            |  6 +++---
>  arch/x86/platform/efi/efi_64.c |  2 +-
>  arch/x86/power/hibernate_64.c  |  6 +++---
>  7 files changed, 33 insertions(+), 27 deletions(-)

> +/*
> + * When memory was added make sure all the processes MM have
> + * suitable PGD entries in the local PGD level page.
> + */
> +void sync_global_pgds(unsigned long start, unsigned long end)
> +{
> +	if (pgtable_l5_enabled)
> +		sync_global_pgds_57(start, end);
> +	else
> +		sync_global_pgds_48(start, end);
> +}

We should use the _l4 and _l5 postfixes instead of random _57 and _48 that is 
pretty cryptic to most readers of the code.

Thanks,

	Ingo