powerpc/mm/nohash: MM_SLICE is only used by book3s 64

BOOKE code is dead code as per the Kconfig details. So make it simpler
by enabling MM_SLICE only for book3s_64. The changes w.r.t nohash is just
removing deadcode. W.r.t ppc64, 4k without hugetlb will now enable MM_SLICE.
But that is good, because we reduce one extra variant which probably is not
getting tested much.

Reviewed-by: Paul Mackerras <[e-mail]>
Signed-off-by: Aneesh Kumar K.V <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/include/asm/mmu-book3e.h

···
 	unsigned int	id;
 	unsigned int	active;
 	unsigned long	vdso_base;
-#ifdef CONFIG_PPC_MM_SLICES
-	u64 low_slices_psize;   /* SLB page size encodings */
-	u64 high_slices_psize;  /* 4 bits per slice for now */
-	u16 user_psize;         /* page size index */
-#endif
 #ifdef CONFIG_PPC_64K_PAGES
 	/* for 4K PTE fragment support */
 	void *pte_frag;

arch/powerpc/include/asm/nohash/64/pgtable.h

···
 #include <asm/nohash/pte-book3e.h>
 #include <asm/pte-common.h>
 
-#ifdef CONFIG_PPC_MM_SLICES
-#define HAVE_ARCH_UNMAPPED_AREA
-#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
-#endif /* CONFIG_PPC_MM_SLICES */
-
 #ifndef __ASSEMBLY__
 /* pte_clear moved to later in this file */
 

arch/powerpc/mm/hugetlbpage-book3e.c

···
 
 	mm = vma->vm_mm;
 
-#ifdef CONFIG_PPC_MM_SLICES
-	psize = get_slice_psize(mm, ea);
-	tsize = mmu_get_tsize(psize);
-	shift = mmu_psize_defs[psize].shift;
-#else
 	psize = vma_mmu_pagesize(vma);
 	shift = __ilog2(psize);
 	tsize = shift - 10;
-#endif
-
 	/*
 	 * We can't be interrupted while we're setting up the MAS
 	 * regusters or after we've confirmed that no tlb exists.

arch/powerpc/mm/mmu_context_nohash.c

···
 
 	mm->context.id = MMU_NO_CONTEXT;
 	mm->context.active = 0;
-
-#ifdef CONFIG_PPC_MM_SLICES
-	slice_set_user_psize(mm, mmu_virtual_psize);
-#endif
-
 	return 0;
 }
 

arch/powerpc/platforms/Kconfig.cputype

···
 
 config PPC_MM_SLICES
 	bool
-	default y if (!PPC_FSL_BOOK3E && PPC64 && HUGETLB_PAGE) || (PPC_STD_MMU_64 && PPC_64K_PAGES)
+	default y if PPC_STD_MMU_64
 	default n
 
 config PPC_HAVE_PMU_SUPPORT