[PATCH v3 4/7] x86/mm: Introduce _set_memory_prot()

[Dan Williams]

On Fri, Feb 21, 2020 at 10:25 AM Logan Gunthorpe <logang at deltatee.com> wrote:
>
> For use in the 32bit arch_add_memory() to set the pgprot type of the
> memory to add.
>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: Ingo Molnar <mingo at redhat.com>
> Cc: Borislav Petkov <bp at alien8.de>
> Cc: "H. Peter Anvin" <hpa at zytor.com>
> Cc: x86 at kernel.org
> Cc: Dave Hansen <dave.hansen at linux.intel.com>
> Cc: Andy Lutomirski <luto at kernel.org>
> Cc: Peter Zijlstra <peterz at infradead.org>
> Signed-off-by: Logan Gunthorpe <logang at deltatee.com>
> ---
>  arch/x86/include/asm/set_memory.h | 1 +
>  arch/x86/mm/pat/set_memory.c      | 7 +++++++
>  2 files changed, 8 insertions(+)
>
> diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
> index 64c3dce374e5..0aca959cf9a4 100644
> --- a/arch/x86/include/asm/set_memory.h
> +++ b/arch/x86/include/asm/set_memory.h
> @@ -34,6 +34,7 @@
>   * The caller is required to take care of these.
>   */
>
> +int _set_memory_prot(unsigned long addr, int numpages, pgprot_t prot);

I wonder if this should be separated from the naming convention of the
other routines because this is only an internal helper for code paths
where the prot was established by an upper layer. For example, I
expect that the kernel does not want new usages to make the mistake of
calling:

   _set_memory_prot(..., pgprot_writecombine(pgprot))

...instead of

    _set_memory_wc()

I'm thinking just a double underscore rename (__set_memory_prot) and a
kerneldoc comment for that  pointing people to use the direct
_set_memory_<cachemode> helpers.

With that you can add:

Reviewed-by: Dan Williams <dan.j.williams at intel.com>