Re: [PATCH v2 5/6] x86, mm, pat: Add pgprot_writethrough() for WT

[Konrad Rzeszutek Wilk]

On Wed, Sep 10, 2014 at 10:51:49AM -0600, Toshi Kani wrote:
> This patch adds pgprot_writethrough() for setting WT to a given
> pgprot_t.
> 
> Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/pgtable_types.h |    3 +++
>  arch/x86/mm/pat.c                    |   10 ++++++++++
>  include/asm-generic/pgtable.h        |    4 ++++
>  3 files changed, 17 insertions(+)
> 
> diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
> index bd2f50f..cc7c65d 100644
> --- a/arch/x86/include/asm/pgtable_types.h
> +++ b/arch/x86/include/asm/pgtable_types.h
> @@ -394,6 +394,9 @@ extern int nx_enabled;
>  #define pgprot_writecombine	pgprot_writecombine
>  extern pgprot_t pgprot_writecombine(pgprot_t prot);
>  
> +#define pgprot_writethrough	pgprot_writethrough
> +extern pgprot_t pgprot_writethrough(pgprot_t prot);
> +
>  /* Indicate that x86 has its own track and untrack pfn vma functions */
>  #define __HAVE_PFNMAP_TRACKING
>  
> diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
> index 7644967..97aab95 100644
> --- a/arch/x86/mm/pat.c
> +++ b/arch/x86/mm/pat.c
> @@ -875,6 +875,16 @@ pgprot_t pgprot_writecombine(pgprot_t prot)
>  }
>  EXPORT_SYMBOL_GPL(pgprot_writecombine);
>  
> +pgprot_t pgprot_writethrough(pgprot_t prot)
> +{
> +	if (pat_enabled)
> +		return __pgprot(pgprot_val(prot) |
> +				cachemode2protval(_PAGE_CACHE_MODE_WT));
> +	else
> +		return pgprot_noncached(prot);
> +}
> +EXPORT_SYMBOL_GPL(pgprot_writethrough);
> +
>  #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_X86_PAT)
>  
>  static struct memtype *memtype_get_idx(loff_t pos)
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 53b2acc..1af0ed9 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -249,6 +249,10 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
>  #define pgprot_writecombine pgprot_noncached
>  #endif
>  
> +#ifndef pgprot_writethrough
> +#define pgprot_writethrough pgprot_noncached
> +#endif
> +
>  /*
>   * When walking page tables, get the address of the next boundary,
>   * or the end address of the range if that comes earlier.  Although no
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