Messages in this thread Patch in this message | | | From | Haozhong Zhang <> | Subject | [PATCH v4 1/3] x86/mm: add function to check if a pfn is UC/UC- | Date | Fri, 3 Nov 2017 13:53:25 +0800 |
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pat_pfn_is_uc(pfn) is added and will be used by KVM to check whether the memory type of a host pfn is UC/UC-.
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> --- arch/x86/include/asm/pat.h | 2 ++ arch/x86/mm/pat.c | 14 ++++++++++++++ 2 files changed, 16 insertions(+)
diff --git a/arch/x86/include/asm/pat.h b/arch/x86/include/asm/pat.h index fffb2794dd89..4027d9fb10a8 100644 --- a/arch/x86/include/asm/pat.h +++ b/arch/x86/include/asm/pat.h @@ -21,4 +21,6 @@ int io_reserve_memtype(resource_size_t start, resource_size_t end, void io_free_memtype(resource_size_t start, resource_size_t end); +bool pat_pfn_is_uc(pfn_t pfn); + #endif /* _ASM_X86_PAT_H */ diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index fe7d57a8fb60..71fe9c29727e 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -677,6 +677,20 @@ static enum page_cache_mode lookup_memtype(u64 paddr) return rettype; } +/** + * Check whether the memory type of a pfn is UC or UC-. The result is + * valid only when PAT is enabled. + * + * Returns true if it is; otherwise, returns false. + */ +bool pat_pfn_is_uc(pfn_t pfn) +{ + enum page_cache_mode cm = lookup_memtype(pfn_t_to_phys(pfn)); + + return cm == _PAGE_CACHE_MODE_UC || cm == _PAGE_CACHE_MODE_UC_MINUS; +} +EXPORT_SYMBOL_GPL(pat_pfn_is_uc); + /** * io_reserve_memtype - Request a memory type mapping for a region of memory * @start: start (physical address) of the region -- 2.14.1
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