diff options
| -rw-r--r-- | arch/x86/mm/pat.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 1a9d0f07593..71aa6f7246c 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -574,6 +574,51 @@ unlock_ret: /** + * lookup_memtype - Looksup the memory type for a physical address + * @paddr: physical address of which memory type needs to be looked up + * + * Only to be called when PAT is enabled + * + * Returns _PAGE_CACHE_WB, _PAGE_CACHE_WC, _PAGE_CACHE_UC_MINUS or + * _PAGE_CACHE_UC + */ +static unsigned long lookup_memtype(u64 paddr) +{ + int rettype = _PAGE_CACHE_WB; + struct memtype *entry; + + if (is_ISA_range(paddr, paddr + PAGE_SIZE - 1)) + return rettype; + + if (pat_pagerange_is_ram(paddr, paddr + PAGE_SIZE)) { + struct page *page; + spin_lock(&memtype_lock); + page = pfn_to_page(paddr >> PAGE_SHIFT); + rettype = get_page_memtype(page); + spin_unlock(&memtype_lock); + /* + * -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_WB; + + return rettype; + } + + spin_lock(&memtype_lock); + + entry = memtype_rb_search(&memtype_rbroot, paddr); + if (entry != NULL) + rettype = entry->type; + else + rettype = _PAGE_CACHE_UC_MINUS; + + spin_unlock(&memtype_lock); + return rettype; +} + +/** * io_reserve_memtype - Request a memory type mapping for a region of memory * @start: start (physical address) of the region * @end: end (physical address) of the region |