On Tue, 2014-08-19 at 15:25 +0200, jgr...@suse.com wrote:
> From: Juergen Gross <jgr...@suse.com>
>
> At the moment there are a lot of places that handle setting or getting
> the page cache mode by treating the pgprot bits equal to the cache mode.
> This is only true because there are a lot of assumptions about the setup
> of the PAT MSR. Otherwise the cache type needs to get translated into
> pgprot bits and vice versa.
>
> This patch tries to prepare for that by introducing a seperate type
> for the cache mode and adding functions to translate between those and pgprot
> values.
>
> To avoid too much performance penalty the translation between cache mode
> and pgprot values is done via tables which contain the relevant information.
> Write-back cache mode is hard-wired to be 0, all other modes are configurable
> via those tables. For large pages there are translation functions as the
> PAT bit is located at different positions in the ptes of 4k and large pages.
One more comment below..
> diff --git a/arch/x86/include/asm/cacheflush.h
> b/arch/x86/include/asm/cacheflush.h
:
> -static inline void set_page_memtype(struct page *pg, unsigned long memtype)
> +static inline void set_page_memtype(struct page *pg,
> + enum page_cache_mode memtype)
> {
> unsigned long memtype_flags = _PGMT_DEFAULT;
> unsigned long old_flags;
> unsigned long new_flags;
>
> switch (memtype) {
> - case _PAGE_CACHE_WC:
> + case _PAGE_CACHE_MODE_WC:
> memtype_flags = _PGMT_WC;
> break;
> - case _PAGE_CACHE_UC_MINUS:
> + case _PAGE_CACHE_MODE_UC_MINUS:
> memtype_flags = _PGMT_UC_MINUS;
> break;
> - case _PAGE_CACHE_WB:
> + case _PAGE_CACHE_MODE_WB:
> + default:
> memtype_flags = _PGMT_WB;
> break;
> }
Adding the "default" case handled as _PGMT_WB is not correct here.
free_ram_pages_type() calls set_page_memtype() with -1, which needs to
be set to _PGMT_DEFAULT.
Thanks,
-Toshi
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