x86/mm/cpa: Cleanup split_large_page() and its callee

So basically we're generating the pte_t * from a struct page and
we're handing it down to the __split_large_page() internal version
which then goes and gets back struct page * from it because it
needs it.

Change the caller to hand down struct page * directly and the
callee can compute the pte_t itself.

Net save is one virt_to_page() call and simpler code. While at
it, make __split_large_page() static.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1363886217-24703-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/pgtable_types.h

@@ -351,7 +351,6 @@ static inline void update_page_count(int level, unsigned long pages) { }
  * as a pte too.
  */
 extern pte_t *lookup_address(unsigned long address, unsigned int *level);
-extern int __split_large_page(pte_t *kpte, unsigned long address, pte_t *pbase);
 extern phys_addr_t slow_virt_to_phys(void *__address);
 
 #endif	/* !__ASSEMBLY__ */

arch/x86/mm/pageattr.c

@@ -542,13 +542,14 @@ out_unlock:
 	return do_split;
 }
 
-int __split_large_page(pte_t *kpte, unsigned long address, pte_t *pbase)
+static int
+__split_large_page(pte_t *kpte, unsigned long address, struct page *base)
 {
+	pte_t *pbase = (pte_t *)page_address(base);
 	unsigned long pfn, pfninc = 1;
 	unsigned int i, level;
 	pte_t *tmp;
 	pgprot_t ref_prot;
-	struct page *base = virt_to_page(pbase);
 
 	spin_lock(&pgd_lock);
 	/*
@@ -633,7 +634,6 @@ int __split_large_page(pte_t *kpte, unsigned long address, pte_t *pbase)
 
 static int split_large_page(pte_t *kpte, unsigned long address)
 {
-	pte_t *pbase;
 	struct page *base;
 
 	if (!debug_pagealloc)
@@ -644,8 +644,7 @@ static int split_large_page(pte_t *kpte, unsigned long address)
 	if (!base)
 		return -ENOMEM;
 
-	pbase = (pte_t *)page_address(base);
-	if (__split_large_page(kpte, address, pbase))
+	if (__split_large_page(kpte, address, base))
 		__free_page(base);
 
 	return 0;