Commit-ID: 35a5a10411d87e24b46a7a9dda8d08ef9961b783 Gitweb: http://git.kernel.org/tip/35a5a10411d87e24b46a7a9dda8d08ef9961b783 Author: Toshi Kani <toshi.kani@xxxxxx> AuthorDate: Thu, 4 Jun 2015 18:55:19 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Sun, 7 Jun 2015 15:28:59 +0200 x86/mm/pat: Extend set_page_memtype() to support Write-Through type As set_memory_wb() calls free_ram_pages_type(), which then calls set_page_memtype() with -1, _PGMT_DEFAULT is used for tracking the WB type. _PGMT_WB is defined but unused. Thus, rename _PGMT_DEFAULT to _PGMT_WB to clarify the usage, and release the slot used by _PGMT_WB. Furthermore, change free_ram_pages_type() to call set_page_memtype() with _PGMT_WB, and get_page_memtype() to return _PAGE_CACHE_MODE_WB for _PGMT_WB. Then, define _PGMT_WT in the freed slot. This allows set_page_memtype() to track the WT type. Signed-off-by: Toshi Kani <toshi.kani@xxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Elliott@xxxxxx Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Luis R. Rodriguez <mcgrof@xxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: arnd@xxxxxxxx Cc: hch@xxxxxx Cc: hmh@xxxxxxxxxx Cc: jgross@xxxxxxxx Cc: konrad.wilk@xxxxxxxxxx Cc: linux-mm <linux-mm@xxxxxxxxx> Cc: linux-nvdimm@xxxxxxxxxxxx Cc: stefan.bader@xxxxxxxxxxxxx Cc: yigal@xxxxxxxxxxxxx Link: http://lkml.kernel.org/r/1433436928-31903-12-git-send-email-bp@xxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/mm/pat.c | 59 +++++++++++++++++++++++++++---------------------------- 1 file changed, 29 insertions(+), 30 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 076187c..188e3e0 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -70,18 +70,22 @@ __setup("debugpat", pat_debug_setup); #ifdef CONFIG_X86_PAT /* - * X86 PAT uses page flags WC and Uncached together to keep track of - * memory type of pages that have backing page struct. X86 PAT supports 3 - * different memory types, _PAGE_CACHE_MODE_WB, _PAGE_CACHE_MODE_WC and - * _PAGE_CACHE_MODE_UC_MINUS and fourth state where page's memory type has not - * been changed from its default (value of -1 used to denote this). - * Note we do not support _PAGE_CACHE_MODE_UC here. + * X86 PAT uses page flags arch_1 and uncached together to keep track of + * memory type of pages that have backing page struct. + * + * X86 PAT supports 4 different memory types: + * - _PAGE_CACHE_MODE_WB + * - _PAGE_CACHE_MODE_WC + * - _PAGE_CACHE_MODE_UC_MINUS + * - _PAGE_CACHE_MODE_WT + * + * _PAGE_CACHE_MODE_WB is the default type. */ -#define _PGMT_DEFAULT 0 +#define _PGMT_WB 0 #define _PGMT_WC (1UL << PG_arch_1) #define _PGMT_UC_MINUS (1UL << PG_uncached) -#define _PGMT_WB (1UL << PG_uncached | 1UL << PG_arch_1) +#define _PGMT_WT (1UL << PG_uncached | 1UL << PG_arch_1) #define _PGMT_MASK (1UL << PG_uncached | 1UL << PG_arch_1) #define _PGMT_CLEAR_MASK (~_PGMT_MASK) @@ -89,14 +93,14 @@ static inline enum page_cache_mode get_page_memtype(struct page *pg) { unsigned long pg_flags = pg->flags & _PGMT_MASK; - if (pg_flags == _PGMT_DEFAULT) - return -1; + if (pg_flags == _PGMT_WB) + return _PAGE_CACHE_MODE_WB; else if (pg_flags == _PGMT_WC) return _PAGE_CACHE_MODE_WC; else if (pg_flags == _PGMT_UC_MINUS) return _PAGE_CACHE_MODE_UC_MINUS; else - return _PAGE_CACHE_MODE_WB; + return _PAGE_CACHE_MODE_WT; } static inline void set_page_memtype(struct page *pg, @@ -113,11 +117,12 @@ static inline void set_page_memtype(struct page *pg, case _PAGE_CACHE_MODE_UC_MINUS: memtype_flags = _PGMT_UC_MINUS; break; - case _PAGE_CACHE_MODE_WB: - memtype_flags = _PGMT_WB; + case _PAGE_CACHE_MODE_WT: + memtype_flags = _PGMT_WT; break; + case _PAGE_CACHE_MODE_WB: default: - memtype_flags = _PGMT_DEFAULT; + memtype_flags = _PGMT_WB; break; } @@ -401,8 +406,10 @@ static int pat_pagerange_is_ram(resource_size_t start, resource_size_t end) /* * For RAM pages, we use page flags to mark the pages with appropriate type. - * The page flags are limited to three types, WB, WC and UC-. WT and WP requests - * fail with -EINVAL, and UC gets redirected to UC-. + * The page flags are limited to four types, WB (default), WC, WT and UC-. + * WP request fails with -EINVAL, and UC gets redirected to UC-. Setting + * a new memory type is only allowed for a page mapped with the default WB + * type. * * Here we do two passes: * - Find the memtype of all the pages in the range, look for any conflicts. @@ -415,8 +422,7 @@ static int reserve_ram_pages_type(u64 start, u64 end, struct page *page; u64 pfn; - if ((req_type == _PAGE_CACHE_MODE_WT) || - (req_type == _PAGE_CACHE_MODE_WP)) { + if (req_type == _PAGE_CACHE_MODE_WP) { if (new_type) *new_type = _PAGE_CACHE_MODE_UC_MINUS; return -EINVAL; @@ -433,7 +439,7 @@ static int reserve_ram_pages_type(u64 start, u64 end, page = pfn_to_page(pfn); type = get_page_memtype(page); - if (type != -1) { + if (type != _PAGE_CACHE_MODE_WB) { pr_info("x86/PAT: reserve_ram_pages_type failed [mem %#010Lx-%#010Lx], track 0x%x, req 0x%x\n", start, end - 1, type, req_type); if (new_type) @@ -460,7 +466,7 @@ static int free_ram_pages_type(u64 start, u64 end) for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) { page = pfn_to_page(pfn); - set_page_memtype(page, -1); + set_page_memtype(page, _PAGE_CACHE_MODE_WB); } return 0; } @@ -601,7 +607,7 @@ int free_memtype(u64 start, u64 end) * Only to be called when PAT is enabled * * Returns _PAGE_CACHE_MODE_WB, _PAGE_CACHE_MODE_WC, _PAGE_CACHE_MODE_UC_MINUS - * or _PAGE_CACHE_MODE_UC + * or _PAGE_CACHE_MODE_WT. */ static enum page_cache_mode lookup_memtype(u64 paddr) { @@ -613,16 +619,9 @@ static enum page_cache_mode lookup_memtype(u64 paddr) if (pat_pagerange_is_ram(paddr, paddr + PAGE_SIZE)) { struct page *page; - page = pfn_to_page(paddr >> PAGE_SHIFT); - rettype = get_page_memtype(page); - /* - * -1 from get_page_memtype() implies RAM page is in its - * default state and not reserved, and hence of type WB - */ - if (rettype == -1) - rettype = _PAGE_CACHE_MODE_WB; - return rettype; + page = pfn_to_page(paddr >> PAGE_SHIFT); + return get_page_memtype(page); } spin_lock(&memtype_lock); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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