x86, pat: Add lookup_memtype to get the current memtype of a paddr
Add a new routine lookup_memtype() to get the current memtype based on
the PAT reserves and frees.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 1a9d0f0..71aa6f7 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -574,6 +574,51 @@
/**
+ * 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