Re: [PATCH v2 4/6] x86, mm: Add set_memory_wt() for WT

[Konrad Rzeszutek Wilk]

On Wed, Sep 10, 2014 at 10:51:48AM -0600, Toshi Kani wrote:
> This patch adds set_memory_wt(), set_memory_array_wt(), and
> set_pages_array_wt() for setting range(s) of memory to WT.
> 
> Note that set_memory_wt() only works for non-RAM ranges at
> this point due to the current limitation in reserve_memtype().
> This may still be useful when a driver maps the entire NV-DIMM
> range with ioremap_cache() and then modifies a specific range
> to WT with set_memory_wt().
> 
> Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/cacheflush.h |    6 +++
>  arch/x86/mm/pageattr.c            |   73 ++++++++++++++++++++++++++++++++++---
>  2 files changed, 72 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
> index c912680..5bfd5d0 100644
> --- a/arch/x86/include/asm/cacheflush.h
> +++ b/arch/x86/include/asm/cacheflush.h
> @@ -81,7 +81,7 @@ static inline void set_page_memtype(struct page *pg,
>  /*
>   * The set_memory_* API can be used to change various attributes of a virtual
>   * address range. The attributes include:
> - * Cachability   : UnCached, WriteCombining, WriteBack
> + * Cachability   : UnCached, WriteCombining, WriteThrough, WriteBack
>   * Executability : eXeutable, NoteXecutable
>   * Read/Write    : ReadOnly, ReadWrite
>   * Presence      : NotPresent
> @@ -108,9 +108,11 @@ static inline void set_page_memtype(struct page *pg,
>  
>  int _set_memory_uc(unsigned long addr, int numpages);
>  int _set_memory_wc(unsigned long addr, int numpages);
> +int _set_memory_wt(unsigned long addr, int numpages);
>  int _set_memory_wb(unsigned long addr, int numpages);
>  int set_memory_uc(unsigned long addr, int numpages);
>  int set_memory_wc(unsigned long addr, int numpages);
> +int set_memory_wt(unsigned long addr, int numpages);
>  int set_memory_wb(unsigned long addr, int numpages);
>  int set_memory_x(unsigned long addr, int numpages);
>  int set_memory_nx(unsigned long addr, int numpages);
> @@ -121,10 +123,12 @@ int set_memory_4k(unsigned long addr, int numpages);
>  
>  int set_memory_array_uc(unsigned long *addr, int addrinarray);
>  int set_memory_array_wc(unsigned long *addr, int addrinarray);
> +int set_memory_array_wt(unsigned long *addr, int addrinarray);
>  int set_memory_array_wb(unsigned long *addr, int addrinarray);
>  
>  int set_pages_array_uc(struct page **pages, int addrinarray);
>  int set_pages_array_wc(struct page **pages, int addrinarray);
> +int set_pages_array_wt(struct page **pages, int addrinarray);
>  int set_pages_array_wb(struct page **pages, int addrinarray);
>  
>  /*
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index 6917b39..2dda151 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -1484,12 +1484,10 @@ EXPORT_SYMBOL(set_memory_uc);
>  static int _set_memory_array(unsigned long *addr, int addrinarray,
>  		enum page_cache_mode new_type)
>  {
> +	enum page_cache_mode set_type;
>  	int i, j;
>  	int ret;
>  
> -	/*
> -	 * for now UC MINUS. see comments in ioremap_nocache()
> -	 */
>  	for (i = 0; i < addrinarray; i++) {
>  		ret = reserve_memtype(__pa(addr[i]), __pa(addr[i]) + PAGE_SIZE,
>  					new_type, NULL);
> @@ -1497,9 +1495,12 @@ static int _set_memory_array(unsigned long *addr, int addrinarray,
>  			goto out_free;
>  	}
>  
> +	/* If WC, set to UC- first and then WC */
> +	set_type = (new_type == _PAGE_CACHE_MODE_WC) ?
> +				_PAGE_CACHE_MODE_UC_MINUS : new_type;
> +
>  	ret = change_page_attr_set(addr, addrinarray,
> -				   cachemode2pgprot(_PAGE_CACHE_MODE_UC_MINUS),
> -				   1);
> +				   cachemode2pgprot(set_type), 1);
>  
>  	if (!ret && new_type == _PAGE_CACHE_MODE_WC)
>  		ret = change_page_attr_set_clr(addr, addrinarray,
> @@ -1527,10 +1528,22 @@ EXPORT_SYMBOL(set_memory_array_uc);
>  
>  int set_memory_array_wc(unsigned long *addr, int addrinarray)
>  {
> +	if (!pat_enabled)
> +		return set_memory_array_uc(addr, addrinarray);
> +
>  	return _set_memory_array(addr, addrinarray, _PAGE_CACHE_MODE_WC);
>  }
>  EXPORT_SYMBOL(set_memory_array_wc);
>  
> +int set_memory_array_wt(unsigned long *addr, int addrinarray)
> +{
> +	if (!pat_enabled)
> +		return set_memory_array_uc(addr, addrinarray);
> +
> +	return _set_memory_array(addr, addrinarray, _PAGE_CACHE_MODE_WT);
> +}
> +EXPORT_SYMBOL(set_memory_array_wt);
> +
>  int _set_memory_wc(unsigned long addr, int numpages)
>  {
>  	int ret;
> @@ -1574,6 +1587,37 @@ out_err:
>  }
>  EXPORT_SYMBOL(set_memory_wc);
>  
> +int _set_memory_wt(unsigned long addr, int numpages)
> +{
> +	return change_page_attr_set(&addr, numpages,
> +				    cachemode2pgprot(_PAGE_CACHE_MODE_WT), 0);
> +}
> +
> +int set_memory_wt(unsigned long addr, int numpages)
> +{
> +	int ret;
> +
> +	if (!pat_enabled)
> +		return set_memory_uc(addr, numpages);
> +
> +	ret = reserve_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE,
> +			      _PAGE_CACHE_MODE_WT, NULL);
> +	if (ret)
> +		goto out_err;
> +
> +	ret = _set_memory_wt(addr, numpages);
> +	if (ret)
> +		goto out_free;
> +
> +	return 0;
> +
> +out_free:
> +	free_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE);
> +out_err:
> +	return ret;
> +}
> +EXPORT_SYMBOL(set_memory_wt);
> +
>  int _set_memory_wb(unsigned long addr, int numpages)
>  {
>  	/* WB cache mode is hard wired to all cache attribute bits being 0 */
> @@ -1666,6 +1710,7 @@ static int _set_pages_array(struct page **pages, int addrinarray,
>  {
>  	unsigned long start;
>  	unsigned long end;
> +	enum page_cache_mode set_type;
>  	int i;
>  	int free_idx;
>  	int ret;
> @@ -1679,8 +1724,12 @@ static int _set_pages_array(struct page **pages, int addrinarray,
>  			goto err_out;
>  	}
>  
> +	/* If WC, set to UC- first and then WC */
> +	set_type = (new_type == _PAGE_CACHE_MODE_WC) ?
> +				_PAGE_CACHE_MODE_UC_MINUS : new_type;
> +
>  	ret = cpa_set_pages_array(pages, addrinarray,
> -			cachemode2pgprot(_PAGE_CACHE_MODE_UC_MINUS));
> +				  cachemode2pgprot(set_type));
>  	if (!ret && new_type == _PAGE_CACHE_MODE_WC)
>  		ret = change_page_attr_set_clr(NULL, addrinarray,
>  					       cachemode2pgprot(
> @@ -1710,10 +1759,22 @@ EXPORT_SYMBOL(set_pages_array_uc);
>  
>  int set_pages_array_wc(struct page **pages, int addrinarray)
>  {
> +	if (!pat_enabled)
> +		return set_pages_array_uc(pages, addrinarray);
> +
>  	return _set_pages_array(pages, addrinarray, _PAGE_CACHE_MODE_WC);
>  }
>  EXPORT_SYMBOL(set_pages_array_wc);
>  
> +int set_pages_array_wt(struct page **pages, int addrinarray)
> +{
> +	if (!pat_enabled)
> +		return set_pages_array_uc(pages, addrinarray);
> +
> +	return _set_pages_array(pages, addrinarray, _PAGE_CACHE_MODE_WT);
> +}
> +EXPORT_SYMBOL(set_pages_array_wt);
> +
>  int set_pages_wb(struct page *page, int numpages)
>  {
>  	unsigned long addr = (unsigned long)page_address(page);
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