x86: CPA use the existing pfn in split as well

When splitting large pages, we ge the pfn from the existing entry
instead of calculating it ourself.

This removes the last remaining range restriction of the cpa code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/pageattr.c

@@ -221,8 +221,7 @@ static int split_large_page(pte_t *kpte, unsigned long address)
 {
 	pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
 	gfp_t gfp_flags = GFP_KERNEL;
-	unsigned long flags;
-	unsigned long addr;
+	unsigned long flags, addr, pfn;
 	pte_t *pbase, *tmp;
 	struct page *base;
 	unsigned int i, level;
@@ -253,8 +252,12 @@ static int split_large_page(pte_t *kpte, unsigned long address)
 	paravirt_alloc_pt(&init_mm, page_to_pfn(base));
 #endif
 
-	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
-		set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
+	/*
+	 * Get the target pfn from the original entry:
+	 */
+	pfn = pte_pfn(*kpte);
+	for (i = 0; i < PTRS_PER_PTE; i++, pfn++)
+		set_pte(&pbase[i], pfn_pte(pfn, ref_prot));
 
 	/*
 	 * Install the new, split up pagetable. Important detail here: