[PATCH RFC v9 02/25] set_memory: Introduce set_memory_pkey() stub

[Linu Cherian]

Kevin,

On Tue, Aug 18, 2026 at 03:08:44PM +0100, Kevin Brodsky wrote:
> Introduce a new function, set_memory_pkey(), which sets the
> protection key (pkey) of pages in the specified linear mapping
> range. Architectures implementing kernel pkeys (kpkeys) must
> provide a suitable implementation; an empty stub is added as

Could you make it explicit here why we are restricting this only
to the linear mapping range ? Would be helpful to add the reasoning
in the commit message and as comments.

Essentially we are also making a assumption here that there are no
aliases to the linear map ?

> fallback.
> 
> Signed-off-by: Kevin Brodsky <kevin.brodsky at arm.com>
> ---
>  include/linux/set_memory.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h
> index 3030d9245f5a..7b3a8bfde3c6 100644
> --- a/include/linux/set_memory.h
> +++ b/include/linux/set_memory.h
> @@ -84,4 +84,11 @@ static inline int set_memory_decrypted(unsigned long addr, int numpages)
>  }
>  #endif /* CONFIG_ARCH_HAS_MEM_ENCRYPT */
>  
> +#ifndef CONFIG_ARCH_HAS_KPKEYS
> +static inline int set_memory_pkey(unsigned long addr, int numpages, int pkey)
> +{
> +	return 0;
> +}
> +#endif

Would be better to make this (linar map range)constraint on the API name or that passed
as a boolean flag ?

Also, it would be better to have the __is_lm_address checks in this generic wrapper which
then calls arch_set_memory_pkey ?


--
Linu Cherian