powerpc/mm: cleanup HPAGE_SHIFT setup

Only book3s/64 may select default among several HPAGE_SHIFT at runtime.
8xx always defines 512K pages as default
FSL_BOOK3E always defines 4M pages as default

This patch limits HUGETLB_PAGE_SIZE_VARIABLE to book3s/64
moves the definitions in subarches files.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Kconfig

@@ -390,7 +390,7 @@ source "kernel/Kconfig.hz"
 
 config HUGETLB_PAGE_SIZE_VARIABLE
 	bool
-	depends on HUGETLB_PAGE
+	depends on HUGETLB_PAGE && PPC_BOOK3S_64
 	default y
 
 config MATH_EMULATION

arch/powerpc/include/asm/hugetlb.h

@@ -15,6 +15,8 @@
 
 extern bool hugetlb_disabled;
 
+void hugetlbpage_init_default(void);
+
 void flush_dcache_icache_hugepage(struct page *page);
 
 int slice_is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,

arch/powerpc/include/asm/page.h

@@ -28,10 +28,15 @@
 #define PAGE_SIZE		(ASM_CONST(1) << PAGE_SHIFT)
 
 #ifndef __ASSEMBLY__
-#ifdef CONFIG_HUGETLB_PAGE
-extern unsigned int HPAGE_SHIFT;
-#else
+#ifndef CONFIG_HUGETLB_PAGE
 #define HPAGE_SHIFT PAGE_SHIFT
+#elif defined(CONFIG_PPC_BOOK3S_64)
+extern unsigned int hpage_shift;
+#define HPAGE_SHIFT hpage_shift
+#elif defined(CONFIG_PPC_8xx)
+#define HPAGE_SHIFT		19	/* 512k pages */
+#elif defined(CONFIG_PPC_FSL_BOOK3E)
+#define HPAGE_SHIFT		22	/* 4M pages */
 #endif
 #define HPAGE_SIZE		((1UL) << HPAGE_SHIFT)
 #define HPAGE_MASK		(~(HPAGE_SIZE - 1))

arch/powerpc/mm/book3s64/hash_hugetlbpage.c

@@ -15,6 +15,9 @@
 #include <asm/cacheflush.h>
 #include <asm/machdep.h>
 
+unsigned int hpage_shift;
+EXPORT_SYMBOL(hpage_shift);
+
 extern long hpte_insert_repeating(unsigned long hash, unsigned long vpn,
 				  unsigned long pa, unsigned long rlags,
 				  unsigned long vflags, int psize, int ssize);
@@ -150,3 +153,16 @@ void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr
 							   old_pte, pte);
 	set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
 }
+
+void hugetlbpage_init_default(void)
+{
+	/* Set default large page size. Currently, we pick 16M or 1M
+	 * depending on what is available
+	 */
+	if (mmu_psize_defs[MMU_PAGE_16M].shift)
+		hpage_shift = mmu_psize_defs[MMU_PAGE_16M].shift;
+	else if (mmu_psize_defs[MMU_PAGE_1M].shift)
+		hpage_shift = mmu_psize_defs[MMU_PAGE_1M].shift;
+	else if (mmu_psize_defs[MMU_PAGE_2M].shift)
+		hpage_shift = mmu_psize_defs[MMU_PAGE_2M].shift;
+}

arch/powerpc/mm/hugetlbpage.c

@@ -28,9 +28,6 @@
 
 bool hugetlb_disabled = false;
 
-unsigned int HPAGE_SHIFT;
-EXPORT_SYMBOL(HPAGE_SHIFT);
-
 #define hugepd_none(hpd)	(hpd_val(hpd) == 0)
 
 #define PTE_T_ORDER	(__builtin_ffs(sizeof(pte_t)) - __builtin_ffs(sizeof(void *)))
@@ -645,23 +642,9 @@ static int __init hugetlbpage_init(void)
 #endif
 	}
 
-#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
-	/* Default hpage size = 4M on FSL_BOOK3E and 512k on 8xx */
-	if (mmu_psize_defs[MMU_PAGE_4M].shift)
-		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_4M].shift;
-	else if (mmu_psize_defs[MMU_PAGE_512K].shift)
-		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_512K].shift;
-#else
-	/* Set default large page size. Currently, we pick 16M or 1M
-	 * depending on what is available
-	 */
-	if (mmu_psize_defs[MMU_PAGE_16M].shift)
-		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_16M].shift;
-	else if (mmu_psize_defs[MMU_PAGE_1M].shift)
-		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_1M].shift;
-	else if (mmu_psize_defs[MMU_PAGE_2M].shift)
-		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_2M].shift;
-#endif
+	if (IS_ENABLED(HUGETLB_PAGE_SIZE_VARIABLE))
+		hugetlbpage_init_default();
+
 	return 0;
 }