x86: simplify 32-bit cpa largepage splitting

simplify 32-bit cpa largepage splitting: do a pure split and repeat
the pte lookup to get the new pte modified.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 8 insertions, 6 deletions

diff --git a/arch/x86/mm/pageattr_32.c b/arch/x86/mm/pageattr_32.c
index 570a37bf1401..1011b21f8db0 100644
--- a/arch/x86/mm/pageattr_32.c
+++ b/arch/x86/mm/pageattr_32.c
@@ -38,7 +38,7 @@ pte_t *lookup_address(unsigned long address, int *level)
 }
 
 static struct page *
-split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
+split_large_page(unsigned long address, pgprot_t ref_prot)
 {
         unsigned long addr;
         struct page *base;
@@ -58,10 +58,9 @@ split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
         pbase = (pte_t *)page_address(base);
         paravirt_alloc_pt(&init_mm, page_to_pfn(base));
 
-        for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
-                set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
-                                           addr == address ? prot : ref_prot));
-        }
+        for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
+                set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
+
         return base;
 }
 
@@ -101,6 +100,7 @@ static int __change_page_attr(struct page *page, pgprot_t prot)
         BUG_ON(PageHighMem(page));
         address = (unsigned long)page_address(page);
 
+repeat:
         kpte = lookup_address(address, &level);
         if (!kpte)
                 return -EINVAL;
@@ -128,7 +128,8 @@ static int __change_page_attr(struct page *page, pgprot_t prot)
                 set_pte_atomic(kpte, mk_pte(page, prot));
         } else {
                 struct page *split;
-                split = split_large_page(address, prot, ref_prot);
+
+                split = split_large_page(address, ref_prot);
                 if (!split)
                         return -ENOMEM;
 
@@ -136,6 +137,7 @@ static int __change_page_attr(struct page *page, pgprot_t prot)
                  * There's a small window here to waste a bit of RAM:
                  */
                 set_pmd_pte(kpte, address, mk_pte(split, ref_prot));
+                goto repeat;
         }
         return 0;
 }