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Date:   Thu, 2 Jan 2020 10:11:00 +0200
From:   Mike Rapoport <rppt@kernel.org>
To:     Michael Ellerman <mpe@ellerman.id.au>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH] powerpc: add support for folded p4d page tables
Message-ID: <20200102081059.GA12063@rapoport-lnx>
References: <20191209150908.6207-1-rppt@kernel.org>
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Any updates on this?

On Mon, Dec 09, 2019 at 05:09:08PM +0200, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> Implement primitives necessary for the 4th level folding, add walks of p4d
> level where appropriate and replace 5level-fixup.h with pgtable-nop4d.h.
> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
>  arch/powerpc/include/asm/book3s/32/pgtable.h  |  1 -
>  arch/powerpc/include/asm/book3s/64/hash.h     |  4 +-
>  arch/powerpc/include/asm/book3s/64/pgalloc.h  |  4 +-
>  arch/powerpc/include/asm/book3s/64/pgtable.h  | 58 ++++++++++--------
>  arch/powerpc/include/asm/book3s/64/radix.h    |  6 +-
>  arch/powerpc/include/asm/nohash/32/pgtable.h  |  1 -
>  arch/powerpc/include/asm/nohash/64/pgalloc.h  |  2 +-
>  .../include/asm/nohash/64/pgtable-4k.h        | 32 +++++-----
>  arch/powerpc/include/asm/nohash/64/pgtable.h  |  6 +-
>  arch/powerpc/include/asm/pgtable.h            |  8 +++
>  arch/powerpc/kvm/book3s_64_mmu_radix.c        | 59 ++++++++++++++++---
>  arch/powerpc/lib/code-patching.c              |  7 ++-
>  arch/powerpc/mm/book3s32/mmu.c                |  2 +-
>  arch/powerpc/mm/book3s32/tlb.c                |  4 +-
>  arch/powerpc/mm/book3s64/hash_pgtable.c       |  4 +-
>  arch/powerpc/mm/book3s64/radix_pgtable.c      | 19 ++++--
>  arch/powerpc/mm/book3s64/subpage_prot.c       |  6 +-
>  arch/powerpc/mm/hugetlbpage.c                 | 28 +++++----
>  arch/powerpc/mm/kasan/kasan_init_32.c         |  8 +--
>  arch/powerpc/mm/mem.c                         |  4 +-
>  arch/powerpc/mm/nohash/40x.c                  |  4 +-
>  arch/powerpc/mm/nohash/book3e_pgtable.c       | 15 +++--
>  arch/powerpc/mm/pgtable.c                     | 25 +++++++-
>  arch/powerpc/mm/pgtable_32.c                  | 28 +++++----
>  arch/powerpc/mm/pgtable_64.c                  | 10 ++--
>  arch/powerpc/mm/ptdump/hashpagetable.c        | 20 ++++++-
>  arch/powerpc/mm/ptdump/ptdump.c               | 22 ++++++-
>  arch/powerpc/xmon/xmon.c                      | 17 +++++-
>  28 files changed, 284 insertions(+), 120 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
> index 0796533d37dd..e23de69bbaf8 100644
> --- a/arch/powerpc/include/asm/book3s/32/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
> @@ -2,7 +2,6 @@
>  #ifndef _ASM_POWERPC_BOOK3S_32_PGTABLE_H
>  #define _ASM_POWERPC_BOOK3S_32_PGTABLE_H
>  
> -#define __ARCH_USE_5LEVEL_HACK
>  #include <asm-generic/pgtable-nopmd.h>
>  
>  #include <asm/book3s/32/hash.h>
> diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
> index 2781ebf6add4..876d1528c2cf 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash.h
> @@ -134,9 +134,9 @@ static inline int get_region_id(unsigned long ea)
>  
>  #define	hash__pmd_bad(pmd)		(pmd_val(pmd) & H_PMD_BAD_BITS)
>  #define	hash__pud_bad(pud)		(pud_val(pud) & H_PUD_BAD_BITS)
> -static inline int hash__pgd_bad(pgd_t pgd)
> +static inline int hash__p4d_bad(p4d_t p4d)
>  {
> -	return (pgd_val(pgd) == 0);
> +	return (p4d_val(p4d) == 0);
>  }
>  #ifdef CONFIG_STRICT_KERNEL_RWX
>  extern void hash__mark_rodata_ro(void);
> diff --git a/arch/powerpc/include/asm/book3s/64/pgalloc.h b/arch/powerpc/include/asm/book3s/64/pgalloc.h
> index f6968c811026..08603089ea5f 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgalloc.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgalloc.h
> @@ -87,9 +87,9 @@ static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
>  	kmem_cache_free(PGT_CACHE(PGD_INDEX_SIZE), pgd);
>  }
>  
> -static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pud_t *pud)
> +static inline void p4d_populate(struct mm_struct *mm, p4d_t *pgd, pud_t *pud)
>  {
> -	*pgd =  __pgd(__pgtable_ptr_val(pud) | PGD_VAL_BITS);
> +	*pgd =  __p4d(__pgtable_ptr_val(pud) | PGD_VAL_BITS);
>  }
>  
>  static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index b01624e5c467..96fc48a42f4d 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -2,7 +2,7 @@
>  #ifndef _ASM_POWERPC_BOOK3S_64_PGTABLE_H_
>  #define _ASM_POWERPC_BOOK3S_64_PGTABLE_H_
>  
> -#include <asm-generic/5level-fixup.h>
> +#include <asm-generic/pgtable-nop4d.h>
>  
>  #ifndef __ASSEMBLY__
>  #include <linux/mmdebug.h>
> @@ -251,7 +251,7 @@ extern unsigned long __pmd_frag_size_shift;
>  /* Bits to mask out from a PUD to get to the PMD page */
>  #define PUD_MASKED_BITS		0xc0000000000000ffUL
>  /* Bits to mask out from a PGD to get to the PUD page */
> -#define PGD_MASKED_BITS		0xc0000000000000ffUL
> +#define P4D_MASKED_BITS		0xc0000000000000ffUL
>  
>  /*
>   * Used as an indicator for rcu callback functions
> @@ -949,54 +949,60 @@ static inline bool pud_access_permitted(pud_t pud, bool write)
>  	return pte_access_permitted(pud_pte(pud), write);
>  }
>  
> -#define pgd_write(pgd)		pte_write(pgd_pte(pgd))
> +#define __p4d_raw(x)	((p4d_t) { __pgd_raw(x) })
> +static inline __be64 p4d_raw(p4d_t x)
> +{
> +	return pgd_raw(x.pgd);
> +}
> +
> +#define p4d_write(p4d)		pte_write(p4d_pte(p4d))
>  
> -static inline void pgd_clear(pgd_t *pgdp)
> +static inline void p4d_clear(p4d_t *p4dp)
>  {
> -	*pgdp = __pgd(0);
> +	*p4dp = __p4d(0);
>  }
>  
> -static inline int pgd_none(pgd_t pgd)
> +static inline int p4d_none(p4d_t p4d)
>  {
> -	return !pgd_raw(pgd);
> +	return !p4d_raw(p4d);
>  }
>  
> -static inline int pgd_present(pgd_t pgd)
> +static inline int p4d_present(p4d_t p4d)
>  {
> -	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT));
> +	return !!(p4d_raw(p4d) & cpu_to_be64(_PAGE_PRESENT));
>  }
>  
> -static inline pte_t pgd_pte(pgd_t pgd)
> +static inline pte_t p4d_pte(p4d_t p4d)
>  {
> -	return __pte_raw(pgd_raw(pgd));
> +	return __pte_raw(p4d_raw(p4d));
>  }
>  
> -static inline pgd_t pte_pgd(pte_t pte)
> +static inline p4d_t pte_p4d(pte_t pte)
>  {
> -	return __pgd_raw(pte_raw(pte));
> +	return __p4d_raw(pte_raw(pte));
>  }
>  
> -static inline int pgd_bad(pgd_t pgd)
> +static inline int p4d_bad(p4d_t p4d)
>  {
>  	if (radix_enabled())
> -		return radix__pgd_bad(pgd);
> -	return hash__pgd_bad(pgd);
> +		return radix__p4d_bad(p4d);
> +	return hash__p4d_bad(p4d);
>  }
>  
> -#define pgd_access_permitted pgd_access_permitted
> -static inline bool pgd_access_permitted(pgd_t pgd, bool write)
> +#define p4d_access_permitted p4d_access_permitted
> +static inline bool p4d_access_permitted(p4d_t p4d, bool write)
>  {
> -	return pte_access_permitted(pgd_pte(pgd), write);
> +	return pte_access_permitted(p4d_pte(p4d), write);
>  }
>  
> -extern struct page *pgd_page(pgd_t pgd);
> +extern struct page *p4d_page(p4d_t p4d);
>  
>  /* Pointers in the page table tree are physical addresses */
>  #define __pgtable_ptr_val(ptr)	__pa(ptr)
>  
>  #define pmd_page_vaddr(pmd)	__va(pmd_val(pmd) & ~PMD_MASKED_BITS)
>  #define pud_page_vaddr(pud)	__va(pud_val(pud) & ~PUD_MASKED_BITS)
> -#define pgd_page_vaddr(pgd)	__va(pgd_val(pgd) & ~PGD_MASKED_BITS)
> +#define p4d_page_vaddr(p4d)	__va(p4d_val(p4d) & ~P4D_MASKED_BITS)
>  
>  #define pgd_index(address) (((address) >> (PGDIR_SHIFT)) & (PTRS_PER_PGD - 1))
>  #define pud_index(address) (((address) >> (PUD_SHIFT)) & (PTRS_PER_PUD - 1))
> @@ -1010,8 +1016,8 @@ extern struct page *pgd_page(pgd_t pgd);
>  
>  #define pgd_offset(mm, address)	 ((mm)->pgd + pgd_index(address))
>  
> -#define pud_offset(pgdp, addr)	\
> -	(((pud_t *) pgd_page_vaddr(*(pgdp))) + pud_index(addr))
> +#define pud_offset(p4dp, addr)	\
> +	(((pud_t *) p4d_page_vaddr(*(p4dp))) + pud_index(addr))
>  #define pmd_offset(pudp,addr) \
>  	(((pmd_t *) pud_page_vaddr(*(pudp))) + pmd_index(addr))
>  #define pte_offset_kernel(dir,addr) \
> @@ -1366,6 +1372,12 @@ static inline bool pud_is_leaf(pud_t pud)
>  	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
>  }
>  
> +#define p4d_is_leaf p4d_is_leaf
> +static inline bool p4d_is_leaf(p4d_t p4d)
> +{
> +	return !!(p4d_raw(p4d) & cpu_to_be64(_PAGE_PTE));
> +}
> +
>  #define pgd_is_leaf pgd_is_leaf
>  static inline bool pgd_is_leaf(pgd_t pgd)
>  {
> diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
> index d97db3ad9aae..9bca2ac64220 100644
> --- a/arch/powerpc/include/asm/book3s/64/radix.h
> +++ b/arch/powerpc/include/asm/book3s/64/radix.h
> @@ -30,7 +30,7 @@
>  /* Don't have anything in the reserved bits and leaf bits */
>  #define RADIX_PMD_BAD_BITS		0x60000000000000e0UL
>  #define RADIX_PUD_BAD_BITS		0x60000000000000e0UL
> -#define RADIX_PGD_BAD_BITS		0x60000000000000e0UL
> +#define RADIX_P4D_BAD_BITS		0x60000000000000e0UL
>  
>  #define RADIX_PMD_SHIFT		(PAGE_SHIFT + RADIX_PTE_INDEX_SIZE)
>  #define RADIX_PUD_SHIFT		(RADIX_PMD_SHIFT + RADIX_PMD_INDEX_SIZE)
> @@ -227,9 +227,9 @@ static inline int radix__pud_bad(pud_t pud)
>  }
>  
>  
> -static inline int radix__pgd_bad(pgd_t pgd)
> +static inline int radix__p4d_bad(p4d_t p4d)
>  {
> -	return !!(pgd_val(pgd) & RADIX_PGD_BAD_BITS);
> +	return !!(p4d_val(p4d) & RADIX_P4D_BAD_BITS);
>  }
>  
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
> index 552b96eef0c8..a0edcc7b0700 100644
> --- a/arch/powerpc/include/asm/nohash/32/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
> @@ -2,7 +2,6 @@
>  #ifndef _ASM_POWERPC_NOHASH_32_PGTABLE_H
>  #define _ASM_POWERPC_NOHASH_32_PGTABLE_H
>  
> -#define __ARCH_USE_5LEVEL_HACK
>  #include <asm-generic/pgtable-nopmd.h>
>  
>  #ifndef __ASSEMBLY__
> diff --git a/arch/powerpc/include/asm/nohash/64/pgalloc.h b/arch/powerpc/include/asm/nohash/64/pgalloc.h
> index b9534a793293..668aee6017e7 100644
> --- a/arch/powerpc/include/asm/nohash/64/pgalloc.h
> +++ b/arch/powerpc/include/asm/nohash/64/pgalloc.h
> @@ -15,7 +15,7 @@ struct vmemmap_backing {
>  };
>  extern struct vmemmap_backing *vmemmap_list;
>  
> -#define pgd_populate(MM, PGD, PUD)	pgd_set(PGD, (unsigned long)PUD)
> +#define p4d_populate(MM, P4D, PUD)	p4d_set(P4D, (unsigned long)PUD)
>  
>  static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
>  {
> diff --git a/arch/powerpc/include/asm/nohash/64/pgtable-4k.h b/arch/powerpc/include/asm/nohash/64/pgtable-4k.h
> index c40ec32b8194..81b1c54e3cf1 100644
> --- a/arch/powerpc/include/asm/nohash/64/pgtable-4k.h
> +++ b/arch/powerpc/include/asm/nohash/64/pgtable-4k.h
> @@ -2,7 +2,7 @@
>  #ifndef _ASM_POWERPC_NOHASH_64_PGTABLE_4K_H
>  #define _ASM_POWERPC_NOHASH_64_PGTABLE_4K_H
>  
> -#include <asm-generic/5level-fixup.h>
> +#include <asm-generic/pgtable-nop4d.h>
>  
>  /*
>   * Entries per page directory level.  The PTE level must use a 64b record
> @@ -45,41 +45,41 @@
>  #define PMD_MASKED_BITS		0
>  /* Bits to mask out from a PUD to get to the PMD page */
>  #define PUD_MASKED_BITS		0
> -/* Bits to mask out from a PGD to get to the PUD page */
> -#define PGD_MASKED_BITS		0
> +/* Bits to mask out from a P4D to get to the PUD page */
> +#define P4D_MASKED_BITS		0
>  
>  
>  /*
>   * 4-level page tables related bits
>   */
>  
> -#define pgd_none(pgd)		(!pgd_val(pgd))
> -#define pgd_bad(pgd)		(pgd_val(pgd) == 0)
> -#define pgd_present(pgd)	(pgd_val(pgd) != 0)
> -#define pgd_page_vaddr(pgd)	(pgd_val(pgd) & ~PGD_MASKED_BITS)
> +#define p4d_none(p4d)		(!p4d_val(p4d))
> +#define p4d_bad(p4d)		(p4d_val(p4d) == 0)
> +#define p4d_present(p4d)	(p4d_val(p4d) != 0)
> +#define p4d_page_vaddr(p4d)	(p4d_val(p4d) & ~P4D_MASKED_BITS)
>  
>  #ifndef __ASSEMBLY__
>  
> -static inline void pgd_clear(pgd_t *pgdp)
> +static inline void p4d_clear(p4d_t *p4dp)
>  {
> -	*pgdp = __pgd(0);
> +	*p4dp = __p4d(0);
>  }
>  
> -static inline pte_t pgd_pte(pgd_t pgd)
> +static inline pte_t p4d_pte(p4d_t p4d)
>  {
> -	return __pte(pgd_val(pgd));
> +	return __pte(p4d_val(p4d));
>  }
>  
> -static inline pgd_t pte_pgd(pte_t pte)
> +static inline p4d_t pte_p4d(pte_t pte)
>  {
> -	return __pgd(pte_val(pte));
> +	return __p4d(pte_val(pte));
>  }
> -extern struct page *pgd_page(pgd_t pgd);
> +extern struct page *p4d_page(p4d_t p4d);
>  
>  #endif /* !__ASSEMBLY__ */
>  
> -#define pud_offset(pgdp, addr)	\
> -  (((pud_t *) pgd_page_vaddr(*(pgdp))) + \
> +#define pud_offset(p4dp, addr)	\
> +  (((pud_t *) p4d_page_vaddr(*(p4dp))) + \
>      (((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1)))
>  
>  #define pud_ERROR(e) \
> diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
> index 9a33b8bd842d..b360f262b9c6 100644
> --- a/arch/powerpc/include/asm/nohash/64/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
> @@ -175,11 +175,11 @@ static inline pud_t pte_pud(pte_t pte)
>  	return __pud(pte_val(pte));
>  }
>  #define pud_write(pud)		pte_write(pud_pte(pud))
> -#define pgd_write(pgd)		pte_write(pgd_pte(pgd))
> +#define p4d_write(pgd)		pte_write(p4d_pte(p4d))
>  
> -static inline void pgd_set(pgd_t *pgdp, unsigned long val)
> +static inline void p4d_set(p4d_t *p4dp, unsigned long val)
>  {
> -	*pgdp = __pgd(val);
> +	*p4dp = __p4d(val);
>  }
>  
>  /*
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index 0e4ec8cc37b7..f831b4d866c3 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -145,6 +145,14 @@ static inline bool pud_is_leaf(pud_t pud)
>  }
>  #endif
>  
> +#ifndef p4d_is_leaf
> +#define p4d_is_leaf p4d_is_leaf
> +static inline bool p4d_is_leaf(p4d_t p4d)
> +{
> +	return false;
> +}
> +#endif
> +
>  #ifndef pgd_is_leaf
>  #define pgd_is_leaf pgd_is_leaf
>  static inline bool pgd_is_leaf(pgd_t pgd)
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> index da857c8ba6e4..28e166cbd963 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> @@ -496,17 +496,39 @@ static void kvmppc_unmap_free_pud(struct kvm *kvm, pud_t *pud,
>  	pud_free(kvm->mm, pud);
>  }
>  
> +static void kvmppc_unmap_free_p4d(struct kvm *kvm, p4d_t *p4d,
> +				  unsigned int lpid)
> +{
> +	unsigned long iu;
> +	p4d_t *p = p4d;
> +
> +	for (iu = 0; iu < PTRS_PER_P4D; ++iu, ++p) {
> +		if (!p4d_present(*p))
> +			continue;
> +		if (p4d_is_leaf(*p)) {
> +			p4d_clear(p);
> +		} else {
> +			pud_t *pud;
> +
> +			pud = pud_offset(p, 0);
> +			kvmppc_unmap_free_pud(kvm, pud, lpid);
> +			p4d_clear(p);
> +		}
> +	}
> +	p4d_free(kvm->mm, p4d);
> +}
> +
>  void kvmppc_free_pgtable_radix(struct kvm *kvm, pgd_t *pgd, unsigned int lpid)
>  {
>  	unsigned long ig;
>  
>  	for (ig = 0; ig < PTRS_PER_PGD; ++ig, ++pgd) {
> -		pud_t *pud;
> +		p4d_t *p4d;
>  
>  		if (!pgd_present(*pgd))
>  			continue;
> -		pud = pud_offset(pgd, 0);
> -		kvmppc_unmap_free_pud(kvm, pud, lpid);
> +		p4d = p4d_offset(pgd, 0);
> +		kvmppc_unmap_free_p4d(kvm, p4d, lpid);
>  		pgd_clear(pgd);
>  	}
>  }
> @@ -568,6 +590,7 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
>  		      unsigned long *rmapp, struct rmap_nested **n_rmap)
>  {
>  	pgd_t *pgd;
> +	p4d_t *p4d, *new_p4d = NULL;
>  	pud_t *pud, *new_pud = NULL;
>  	pmd_t *pmd, *new_pmd = NULL;
>  	pte_t *ptep, *new_ptep = NULL;
> @@ -575,9 +598,15 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
>  
>  	/* Traverse the guest's 2nd-level tree, allocate new levels needed */
>  	pgd = pgtable + pgd_index(gpa);
> -	pud = NULL;
> +	p4d = NULL;
>  	if (pgd_present(*pgd))
> -		pud = pud_offset(pgd, gpa);
> +		p4d = p4d_offset(pgd, gpa);
> +	else
> +		new_p4d = p4d_alloc_one(kvm->mm, gpa);
> +
> +	pud = NULL;
> +	if (p4d_present(*p4d))
> +		pud = pud_offset(p4d, gpa);
>  	else
>  		new_pud = pud_alloc_one(kvm->mm, gpa);
>  
> @@ -599,12 +628,18 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
>  	/* Now traverse again under the lock and change the tree */
>  	ret = -ENOMEM;
>  	if (pgd_none(*pgd)) {
> +		if (!new_p4d)
> +			goto out_unlock;
> +		pgd_populate(kvm->mm, pgd, new_p4d);
> +		new_p4d = NULL;
> +	}
> +	if (p4d_none(*p4d)) {
>  		if (!new_pud)
>  			goto out_unlock;
> -		pgd_populate(kvm->mm, pgd, new_pud);
> +		p4d_populate(kvm->mm, p4d, new_pud);
>  		new_pud = NULL;
>  	}
> -	pud = pud_offset(pgd, gpa);
> +	pud = pud_offset(p4d, gpa);
>  	if (pud_is_leaf(*pud)) {
>  		unsigned long hgpa = gpa & PUD_MASK;
>  
> @@ -1222,6 +1257,7 @@ static ssize_t debugfs_radix_read(struct file *file, char __user *buf,
>  	pgd_t *pgt;
>  	struct kvm_nested_guest *nested;
>  	pgd_t pgd, *pgdp;
> +	p4d_t p4d, *p4dp;
>  	pud_t pud, *pudp;
>  	pmd_t pmd, *pmdp;
>  	pte_t *ptep;
> @@ -1300,7 +1336,14 @@ static ssize_t debugfs_radix_read(struct file *file, char __user *buf,
>  			continue;
>  		}
>  
> -		pudp = pud_offset(&pgd, gpa);
> +		p4dp = p4d_offset(&pgd, gpa);
> +		p4d = READ_ONCE(*p4dp);
> +		if (!(p4d_val(p4d) & _PAGE_PRESENT)) {
> +			gpa = (gpa & P4D_MASK) + P4D_SIZE;
> +			continue;
> +		}
> +
> +		pudp = pud_offset(&p4d, gpa);
>  		pud = READ_ONCE(*pudp);
>  		if (!(pud_val(pud) & _PAGE_PRESENT)) {
>  			gpa = (gpa & PUD_MASK) + PUD_SIZE;
> diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
> index 3345f039a876..7a59f6863cec 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -107,13 +107,18 @@ static inline int unmap_patch_area(unsigned long addr)
>  	pte_t *ptep;
>  	pmd_t *pmdp;
>  	pud_t *pudp;
> +	p4d_t *p4dp;
>  	pgd_t *pgdp;
>  
>  	pgdp = pgd_offset_k(addr);
>  	if (unlikely(!pgdp))
>  		return -EINVAL;
>  
> -	pudp = pud_offset(pgdp, addr);
> +	p4dp = p4d_offset(pgdp, addr);
> +	if (unlikely(!p4dp))
> +		return -EINVAL;
> +
> +	pudp = pud_offset(p4dp, addr);
>  	if (unlikely(!pudp))
>  		return -EINVAL;
>  
> diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
> index 69b2419accef..7479960dc434 100644
> --- a/arch/powerpc/mm/book3s32/mmu.c
> +++ b/arch/powerpc/mm/book3s32/mmu.c
> @@ -312,7 +312,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea)
>  
>  	if (!Hash)
>  		return;
> -	pmd = pmd_offset(pud_offset(pgd_offset(mm, ea), ea), ea);
> +	pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, ea), ea), ea), ea);
>  	if (!pmd_none(*pmd))
>  		add_hash_page(mm->context.id, ea, pmd_val(*pmd));
>  }
> diff --git a/arch/powerpc/mm/book3s32/tlb.c b/arch/powerpc/mm/book3s32/tlb.c
> index 2fcd321040ff..175bc33b41b7 100644
> --- a/arch/powerpc/mm/book3s32/tlb.c
> +++ b/arch/powerpc/mm/book3s32/tlb.c
> @@ -87,7 +87,7 @@ static void flush_range(struct mm_struct *mm, unsigned long start,
>  	if (start >= end)
>  		return;
>  	end = (end - 1) | ~PAGE_MASK;
> -	pmd = pmd_offset(pud_offset(pgd_offset(mm, start), start), start);
> +	pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, start), start), start), start);
>  	for (;;) {
>  		pmd_end = ((start + PGDIR_SIZE) & PGDIR_MASK) - 1;
>  		if (pmd_end > end)
> @@ -145,7 +145,7 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr)
>  		return;
>  	}
>  	mm = (vmaddr < TASK_SIZE)? vma->vm_mm: &init_mm;
> -	pmd = pmd_offset(pud_offset(pgd_offset(mm, vmaddr), vmaddr), vmaddr);
> +	pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, vmaddr), vmaddr), vmaddr), vmaddr);
>  	if (!pmd_none(*pmd))
>  		flush_hash_pages(mm->context.id, vmaddr, pmd_val(*pmd), 1);
>  }
> diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
> index 64733b9cb20a..9cd15937e88a 100644
> --- a/arch/powerpc/mm/book3s64/hash_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/hash_pgtable.c
> @@ -148,6 +148,7 @@ void hash__vmemmap_remove_mapping(unsigned long start,
>  int hash__map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
>  {
>  	pgd_t *pgdp;
> +	p4d_t *p4dp;
>  	pud_t *pudp;
>  	pmd_t *pmdp;
>  	pte_t *ptep;
> @@ -155,7 +156,8 @@ int hash__map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
>  	BUILD_BUG_ON(TASK_SIZE_USER64 > H_PGTABLE_RANGE);
>  	if (slab_is_available()) {
>  		pgdp = pgd_offset_k(ea);
> -		pudp = pud_alloc(&init_mm, pgdp, ea);
> +		p4dp = p4d_offset(pgdp, ea);
> +		pudp = pud_alloc(&init_mm, p4dp, ea);
>  		if (!pudp)
>  			return -ENOMEM;
>  		pmdp = pmd_alloc(&init_mm, pudp, ea);
> diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
> index 974109bb85db..c02427eab084 100644
> --- a/arch/powerpc/mm/book3s64/radix_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
> @@ -64,17 +64,24 @@ static int early_map_kernel_page(unsigned long ea, unsigned long pa,
>  {
>  	unsigned long pfn = pa >> PAGE_SHIFT;
>  	pgd_t *pgdp;
> +	p4d_t *p4dp;
>  	pud_t *pudp;
>  	pmd_t *pmdp;
>  	pte_t *ptep;
>  
>  	pgdp = pgd_offset_k(ea);
>  	if (pgd_none(*pgdp)) {
> +		p4dp = early_alloc_pgtable(PGD_TABLE_SIZE, nid,
> +						region_start, region_end);
> +		pgd_populate(&init_mm, pgdp, p4dp);
> +	}
> +	p4dp = p4d_offset(pgdp, ea);
> +	if (p4d_none(*p4dp)) {
>  		pudp = early_alloc_pgtable(PUD_TABLE_SIZE, nid,
>  						region_start, region_end);
> -		pgd_populate(&init_mm, pgdp, pudp);
> +		p4d_populate(&init_mm, p4dp, pudp);
>  	}
> -	pudp = pud_offset(pgdp, ea);
> +	pudp = pud_offset(p4dp, ea);
>  	if (map_page_size == PUD_SIZE) {
>  		ptep = (pte_t *)pudp;
>  		goto set_the_pte;
> @@ -114,6 +121,7 @@ static int __map_kernel_page(unsigned long ea, unsigned long pa,
>  {
>  	unsigned long pfn = pa >> PAGE_SHIFT;
>  	pgd_t *pgdp;
> +	p4d_t *p4dp;
>  	pud_t *pudp;
>  	pmd_t *pmdp;
>  	pte_t *ptep;
> @@ -136,7 +144,8 @@ static int __map_kernel_page(unsigned long ea, unsigned long pa,
>  	 * boot.
>  	 */
>  	pgdp = pgd_offset_k(ea);
> -	pudp = pud_alloc(&init_mm, pgdp, ea);
> +	p4dp = p4d_offset(pgdp, ea);
> +	pudp = pud_alloc(&init_mm, p4dp, ea);
>  	if (!pudp)
>  		return -ENOMEM;
>  	if (map_page_size == PUD_SIZE) {
> @@ -173,6 +182,7 @@ void radix__change_memory_range(unsigned long start, unsigned long end,
>  {
>  	unsigned long idx;
>  	pgd_t *pgdp;
> +	p4d_t *p4dp;
>  	pud_t *pudp;
>  	pmd_t *pmdp;
>  	pte_t *ptep;
> @@ -185,7 +195,8 @@ void radix__change_memory_range(unsigned long start, unsigned long end,
>  
>  	for (idx = start; idx < end; idx += PAGE_SIZE) {
>  		pgdp = pgd_offset_k(idx);
> -		pudp = pud_alloc(&init_mm, pgdp, idx);
> +		p4dp = p4d_offset(pgdp, idx);
> +		pudp = pud_alloc(&init_mm, p4dp, idx);
>  		if (!pudp)
>  			continue;
>  		if (pud_is_leaf(*pudp)) {
> diff --git a/arch/powerpc/mm/book3s64/subpage_prot.c b/arch/powerpc/mm/book3s64/subpage_prot.c
> index 2ef24a53f4c9..27daeed1a141 100644
> --- a/arch/powerpc/mm/book3s64/subpage_prot.c
> +++ b/arch/powerpc/mm/book3s64/subpage_prot.c
> @@ -54,6 +54,7 @@ static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
>  			     int npages)
>  {
>  	pgd_t *pgd;
> +	p4d_t *p4d;
>  	pud_t *pud;
>  	pmd_t *pmd;
>  	pte_t *pte;
> @@ -62,7 +63,10 @@ static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
>  	pgd = pgd_offset(mm, addr);
>  	if (pgd_none(*pgd))
>  		return;
> -	pud = pud_offset(pgd, addr);
> +	p4d = p4d_offset(pgd, addr);
> +	if (p4d_none(*p4d))
> +		return;
> +	pud = pud_offset(p4d, addr);
>  	if (pud_none(*pud))
>  		return;
>  	pmd = pmd_offset(pud, addr);
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index 73d4873fc7f8..43d463f20fc3 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -112,6 +112,7 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
>  pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
>  {
>  	pgd_t *pg;
> +	p4d_t *p4;
>  	pud_t *pu;
>  	pmd_t *pm;
>  	hugepd_t *hpdp = NULL;
> @@ -121,20 +122,21 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz
>  
>  	addr &= ~(sz-1);
>  	pg = pgd_offset(mm, addr);
> +	p4 = p4d_offset(pg, addr);
>  
>  #ifdef CONFIG_PPC_BOOK3S_64
>  	if (pshift == PGDIR_SHIFT)
>  		/* 16GB huge page */
> -		return (pte_t *) pg;
> +		return (pte_t *) p4;
>  	else if (pshift > PUD_SHIFT) {
>  		/*
>  		 * We need to use hugepd table
>  		 */
>  		ptl = &mm->page_table_lock;
> -		hpdp = (hugepd_t *)pg;
> +		hpdp = (hugepd_t *)p4;
>  	} else {
>  		pdshift = PUD_SHIFT;
> -		pu = pud_alloc(mm, pg, addr);
> +		pu = pud_alloc(mm, p4, addr);
>  		if (!pu)
>  			return NULL;
>  		if (pshift == PUD_SHIFT)
> @@ -159,10 +161,10 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz
>  #else
>  	if (pshift >= PGDIR_SHIFT) {
>  		ptl = &mm->page_table_lock;
> -		hpdp = (hugepd_t *)pg;
> +		hpdp = (hugepd_t *)p4;
>  	} else {
>  		pdshift = PUD_SHIFT;
> -		pu = pud_alloc(mm, pg, addr);
> +		pu = pud_alloc(mm, p4, addr);
>  		if (!pu)
>  			return NULL;
>  		if (pshift >= PUD_SHIFT) {
> @@ -384,7 +386,7 @@ static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
>  	mm_dec_nr_pmds(tlb->mm);
>  }
>  
> -static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
> +static void hugetlb_free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
>  				   unsigned long addr, unsigned long end,
>  				   unsigned long floor, unsigned long ceiling)
>  {
> @@ -394,7 +396,7 @@ static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
>  
>  	start = addr;
>  	do {
> -		pud = pud_offset(pgd, addr);
> +		pud = pud_offset(p4d, addr);
>  		next = pud_addr_end(addr, end);
>  		if (!is_hugepd(__hugepd(pud_val(*pud)))) {
>  			if (pud_none_or_clear_bad(pud))
> @@ -429,8 +431,8 @@ static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
>  	if (end - 1 > ceiling - 1)
>  		return;
>  
> -	pud = pud_offset(pgd, start);
> -	pgd_clear(pgd);
> +	pud = pud_offset(p4d, start);
> +	p4d_clear(p4d);
>  	pud_free_tlb(tlb, pud, start);
>  	mm_dec_nr_puds(tlb->mm);
>  }
> @@ -443,6 +445,7 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
>  			    unsigned long floor, unsigned long ceiling)
>  {
>  	pgd_t *pgd;
> +	p4d_t *p4d;
>  	unsigned long next;
>  
>  	/*
> @@ -465,10 +468,11 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
>  	do {
>  		next = pgd_addr_end(addr, end);
>  		pgd = pgd_offset(tlb->mm, addr);
> +		p4d = p4d_offset(pgd, addr);
>  		if (!is_hugepd(__hugepd(pgd_val(*pgd)))) {
> -			if (pgd_none_or_clear_bad(pgd))
> +			if (p4d_none_or_clear_bad(p4d))
>  				continue;
> -			hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
> +			hugetlb_free_pud_range(tlb, p4d, addr, next, floor, ceiling);
>  		} else {
>  			unsigned long more;
>  			/*
> @@ -481,7 +485,7 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
>  			if (more > next)
>  				next = more;
>  
> -			free_hugepd_range(tlb, (hugepd_t *)pgd, PGDIR_SHIFT,
> +			free_hugepd_range(tlb, (hugepd_t *)p4d, PGDIR_SHIFT,
>  					  addr, next, floor, ceiling);
>  		}
>  	} while (addr = next, addr != end);
> diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
> index 0e6ed4413eea..cac0452cbe1f 100644
> --- a/arch/powerpc/mm/kasan/kasan_init_32.c
> +++ b/arch/powerpc/mm/kasan/kasan_init_32.c
> @@ -36,7 +36,7 @@ static int __ref kasan_init_shadow_page_tables(unsigned long k_start, unsigned l
>  	unsigned long k_cur, k_next;
>  	pgprot_t prot = slab_is_available() ? kasan_prot_ro() : PAGE_KERNEL;
>  
> -	pmd = pmd_offset(pud_offset(pgd_offset_k(k_start), k_start), k_start);
> +	pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset_k(k_start), k_start), k_start), k_start);
>  
>  	for (k_cur = k_start; k_cur != k_end; k_cur = k_next, pmd++) {
>  		pte_t *new;
> @@ -94,7 +94,7 @@ static int __ref kasan_init_region(void *start, size_t size)
>  		block = memblock_alloc(k_end - k_start, PAGE_SIZE);
>  
>  	for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
> -		pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
> +		pmd_t *pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset_k(k_cur), k_cur), k_cur), k_cur);
>  		void *va = block ? block + k_cur - k_start : kasan_get_one_page();
>  		pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);
>  
> @@ -118,7 +118,7 @@ static void __init kasan_remap_early_shadow_ro(void)
>  	kasan_populate_pte(kasan_early_shadow_pte, prot);
>  
>  	for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
> -		pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
> +		pmd_t *pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset_k(k_cur), k_cur), k_cur), k_cur);
>  		pte_t *ptep = pte_offset_kernel(pmd, k_cur);
>  
>  		if ((pte_val(*ptep) & PTE_RPN_MASK) != pa)
> @@ -205,7 +205,7 @@ void __init kasan_early_init(void)
>  	unsigned long addr = KASAN_SHADOW_START;
>  	unsigned long end = KASAN_SHADOW_END;
>  	unsigned long next;
> -	pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(addr), addr), addr);
> +	pmd_t *pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset_k(addr), addr), addr), addr);
>  
>  	BUILD_BUG_ON(KASAN_SHADOW_START & ~PGDIR_MASK);
>  
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index 9488b63dfc87..ed2e24e493b9 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -68,8 +68,8 @@ EXPORT_SYMBOL(kmap_prot);
>  
>  static inline pte_t *virt_to_kpte(unsigned long vaddr)
>  {
> -	return pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr),
> -			vaddr), vaddr), vaddr);
> +	return pte_offset_kernel(pmd_offset(pud_offset(p4d_offset(pgd_offset_k(vaddr),
> +			vaddr), vaddr), vaddr), vaddr);
>  }
>  #endif
>  
> diff --git a/arch/powerpc/mm/nohash/40x.c b/arch/powerpc/mm/nohash/40x.c
> index f348104eb461..7aaf7155e350 100644
> --- a/arch/powerpc/mm/nohash/40x.c
> +++ b/arch/powerpc/mm/nohash/40x.c
> @@ -104,7 +104,7 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
>  		pmd_t *pmdp;
>  		unsigned long val = p | _PMD_SIZE_16M | _PAGE_EXEC | _PAGE_HWWRITE;
>  
> -		pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v);
> +		pmdp = pmd_offset(pud_offset(p4d_offset(pgd_offset_k(v), v), v), v);
>  		*pmdp++ = __pmd(val);
>  		*pmdp++ = __pmd(val);
>  		*pmdp++ = __pmd(val);
> @@ -119,7 +119,7 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
>  		pmd_t *pmdp;
>  		unsigned long val = p | _PMD_SIZE_4M | _PAGE_EXEC | _PAGE_HWWRITE;
>  
> -		pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v);
> +		pmdp = pmd_offset(pud_offset(p4d_offset(pgd_offset_k(v), v), v), v);
>  		*pmdp = __pmd(val);
>  
>  		v += LARGE_PAGE_SIZE_4M;
> diff --git a/arch/powerpc/mm/nohash/book3e_pgtable.c b/arch/powerpc/mm/nohash/book3e_pgtable.c
> index 4637fdd469cf..a62d59a928be 100644
> --- a/arch/powerpc/mm/nohash/book3e_pgtable.c
> +++ b/arch/powerpc/mm/nohash/book3e_pgtable.c
> @@ -73,6 +73,7 @@ static void __init *early_alloc_pgtable(unsigned long size)
>  int __ref map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
>  {
>  	pgd_t *pgdp;
> +	p4d_t *p4dp;
>  	pud_t *pudp;
>  	pmd_t *pmdp;
>  	pte_t *ptep;
> @@ -80,7 +81,10 @@ int __ref map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
>  	BUILD_BUG_ON(TASK_SIZE_USER64 > PGTABLE_RANGE);
>  	if (slab_is_available()) {
>  		pgdp = pgd_offset_k(ea);
> -		pudp = pud_alloc(&init_mm, pgdp, ea);
> +		p4dp = p4d_alloc(&init_mm, pgdp, ea);
> +		if (!p4dp)
> +			return -ENOMEM;
> +		pudp = pud_alloc(&init_mm, p4dp, ea);
>  		if (!pudp)
>  			return -ENOMEM;
>  		pmdp = pmd_alloc(&init_mm, pudp, ea);
> @@ -91,13 +95,16 @@ int __ref map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
>  			return -ENOMEM;
>  	} else {
>  		pgdp = pgd_offset_k(ea);
> -#ifndef __PAGETABLE_PUD_FOLDED
>  		if (pgd_none(*pgdp)) {
>  			pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
>  			pgd_populate(&init_mm, pgdp, pudp);
>  		}
> -#endif /* !__PAGETABLE_PUD_FOLDED */
> -		pudp = pud_offset(pgdp, ea);
> +		p4dp = p4d_offset(pgdp, ea);
> +		if (p4d_none(*p4dp)) {
> +			pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
> +			p4d_populate(&init_mm, p4dp, pmdp);
> +		}
> +		pudp = pud_offset(p4dp, ea);
>  		if (pud_none(*pudp)) {
>  			pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
>  			pud_populate(&init_mm, pudp, pmdp);
> diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
> index e3759b69f81b..dca6a72da26a 100644
> --- a/arch/powerpc/mm/pgtable.c
> +++ b/arch/powerpc/mm/pgtable.c
> @@ -265,6 +265,7 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
>  void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
>  {
>  	pgd_t *pgd;
> +	p4d_t *p4d;
>  	pud_t *pud;
>  	pmd_t *pmd;
>  
> @@ -272,7 +273,9 @@ void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
>  		return;
>  	pgd = mm->pgd + pgd_index(addr);
>  	BUG_ON(pgd_none(*pgd));
> -	pud = pud_offset(pgd, addr);
> +	p4d = p4d_offset(pgd, addr);
> +	BUG_ON(p4d_none(*p4d));
> +	pud = pud_offset(p4d, addr);
>  	BUG_ON(pud_none(*pud));
>  	pmd = pmd_offset(pud, addr);
>  	/*
> @@ -313,6 +316,7 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
>  			bool *is_thp, unsigned *hpage_shift)
>  {
>  	pgd_t pgd, *pgdp;
> +	p4d_t p4d, *p4dp;
>  	pud_t pud, *pudp;
>  	pmd_t pmd, *pmdp;
>  	pte_t *ret_pte;
> @@ -346,13 +350,30 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
>  		goto out_huge;
>  	}
>  
> +	pdshift = P4D_SHIFT;
> +	p4dp = p4d_offset(&pgd, ea);
> +	p4d  = READ_ONCE(*p4dp);
> +
> +	if (p4d_none(p4d))
> +		return NULL;
> +
> +	if (p4d_is_leaf(p4d)) {
> +		ret_pte = (pte_t *)p4dp;
> +		goto out;
> +	}
> +
> +	if (is_hugepd(__hugepd(p4d_val(p4d)))) {
> +		hpdp = (hugepd_t *)&p4d;
> +		goto out_huge;
> +	}
> +
>  	/*
>  	 * Even if we end up with an unmap, the pgtable will not
>  	 * be freed, because we do an rcu free and here we are
>  	 * irq disabled
>  	 */
>  	pdshift = PUD_SHIFT;
> -	pudp = pud_offset(&pgd, ea);
> +	pudp = pud_offset(&p4d, ea);
>  	pud  = READ_ONCE(*pudp);
>  
>  	if (pud_none(pud))
> diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
> index 73b84166d06a..50d97127a801 100644
> --- a/arch/powerpc/mm/pgtable_32.c
> +++ b/arch/powerpc/mm/pgtable_32.c
> @@ -63,7 +63,7 @@ int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
>  	int err = -ENOMEM;
>  
>  	/* Use upper 10 bits of VA to index the first level map */
> -	pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
> +	pd = pmd_offset(pud_offset(p4d_offset(pgd_offset_k(va), va), va), va);
>  	/* Use middle 10 bits of VA to index the second-level map */
>  	if (likely(slab_is_available()))
>  		pg = pte_alloc_kernel(pd, va);
> @@ -130,6 +130,7 @@ static int
>  get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
>  {
>          pgd_t	*pgd;
> +	p4d_t	*p4d;
>  	pud_t	*pud;
>          pmd_t	*pmd;
>          pte_t	*pte;
> @@ -137,17 +138,20 @@ get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
>  
>          pgd = pgd_offset(mm, addr & PAGE_MASK);
>          if (pgd) {
> -		pud = pud_offset(pgd, addr & PAGE_MASK);
> -		if (pud && pud_present(*pud)) {
> -			pmd = pmd_offset(pud, addr & PAGE_MASK);
> -			if (pmd_present(*pmd)) {
> -				pte = pte_offset_map(pmd, addr & PAGE_MASK);
> -				if (pte) {
> -					retval = 1;
> -					*ptep = pte;
> -					if (pmdp)
> -						*pmdp = pmd;
> -					/* XXX caller needs to do pte_unmap, yuck */
> +		p4d = p4d_offset(pgd, addr & PAGE_MASK);
> +		if (p4d && p4d_present(*p4d)) {
> +			pud = pud_offset(p4d, addr & PAGE_MASK);
> +			if (pud && pud_present(*pud)) {
> +				pmd = pmd_offset(pud, addr & PAGE_MASK);
> +				if (pmd_present(*pmd)) {
> +					pte = pte_offset_map(pmd, addr & PAGE_MASK);
> +					if (pte) {
> +						retval = 1;
> +						*ptep = pte;
> +						if (pmdp)
> +							*pmdp = pmd;
> +						/* XXX caller needs to do pte_unmap, yuck */
> +					}
>  				}
>  			}
>  		}
> diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
> index e78832dce7bb..1f86a88fd4bb 100644
> --- a/arch/powerpc/mm/pgtable_64.c
> +++ b/arch/powerpc/mm/pgtable_64.c
> @@ -101,13 +101,13 @@ EXPORT_SYMBOL(__pte_frag_size_shift);
>  
>  #ifndef __PAGETABLE_PUD_FOLDED
>  /* 4 level page table */
> -struct page *pgd_page(pgd_t pgd)
> +struct page *p4d_page(p4d_t p4d)
>  {
> -	if (pgd_is_leaf(pgd)) {
> -		VM_WARN_ON(!pgd_huge(pgd));
> -		return pte_page(pgd_pte(pgd));
> +	if (p4d_is_leaf(p4d)) {
> +		VM_WARN_ON(!p4d_huge(p4d));
> +		return pte_page(p4d_pte(p4d));
>  	}
> -	return virt_to_page(pgd_page_vaddr(pgd));
> +	return virt_to_page(p4d_page_vaddr(p4d));
>  }
>  #endif
>  
> diff --git a/arch/powerpc/mm/ptdump/hashpagetable.c b/arch/powerpc/mm/ptdump/hashpagetable.c
> index a07278027c6f..ac360ad865a8 100644
> --- a/arch/powerpc/mm/ptdump/hashpagetable.c
> +++ b/arch/powerpc/mm/ptdump/hashpagetable.c
> @@ -417,9 +417,9 @@ static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
>  	}
>  }
>  
> -static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
> +static void walk_pud(struct pg_state *st, p4d_t *p4d, unsigned long start)
>  {
> -	pud_t *pud = pud_offset(pgd, 0);
> +	pud_t *pud = pud_offset(p4d, 0);
>  	unsigned long addr;
>  	unsigned int i;
>  
> @@ -431,6 +431,20 @@ static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
>  	}
>  }
>  
> +static void walk_p4d(struct pg_state *st, pgd_t *pgd, unsigned long start)
> +{
> +	p4d_t *p4d = p4d_offset(pgd, 0);
> +	unsigned long addr;
> +	unsigned int i;
> +
> +	for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
> +		addr = start + i * P4D_SIZE;
> +		if (!p4d_none(*p4d))
> +			/* p4d exists */
> +			walk_pud(st, p4d, addr);
> +	}
> +}
> +
>  static void walk_pagetables(struct pg_state *st)
>  {
>  	pgd_t *pgd = pgd_offset_k(0UL);
> @@ -445,7 +459,7 @@ static void walk_pagetables(struct pg_state *st)
>  		addr = KERN_VIRT_START + i * PGDIR_SIZE;
>  		if (!pgd_none(*pgd))
>  			/* pgd exists */
> -			walk_pud(st, pgd, addr);
> +			walk_p4d(st, pgd, addr);
>  	}
>  }
>  
> diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
> index 2f9ddc29c535..5c2f3b916ac8 100644
> --- a/arch/powerpc/mm/ptdump/ptdump.c
> +++ b/arch/powerpc/mm/ptdump/ptdump.c
> @@ -273,9 +273,9 @@ static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
>  	}
>  }
>  
> -static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
> +static void walk_pud(struct pg_state *st, p4d_t *p4d, unsigned long start)
>  {
> -	pud_t *pud = pud_offset(pgd, 0);
> +	pud_t *pud = pud_offset(p4d, 0);
>  	unsigned long addr;
>  	unsigned int i;
>  
> @@ -289,6 +289,22 @@ static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
>  	}
>  }
>  
> +static void walk_p4d(struct pg_state *st, pgd_t *pgd, unsigned long start)
> +{
> +	p4d_t *p4d = p4d_offset(pgd, 0);
> +	unsigned long addr;
> +	unsigned int i;
> +
> +	for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
> +		addr = start + i * P4D_SIZE;
> +		if (!p4d_none(*p4d) && !p4d_is_leaf(*p4d))
> +			/* p4d exists */
> +			walk_pud(st, p4d, addr);
> +		else
> +			note_page(st, addr, 2, p4d_val(*p4d));
> +	}
> +}
> +
>  static void walk_pagetables(struct pg_state *st)
>  {
>  	unsigned int i;
> @@ -302,7 +318,7 @@ static void walk_pagetables(struct pg_state *st)
>  	for (i = pgd_index(addr); i < PTRS_PER_PGD; i++, pgd++, addr += PGDIR_SIZE) {
>  		if (!pgd_none(*pgd) && !pgd_is_leaf(*pgd))
>  			/* pgd exists */
> -			walk_pud(st, pgd, addr);
> +			walk_p4d(st, pgd, addr);
>  		else
>  			note_page(st, addr, 1, pgd_val(*pgd));
>  	}
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index a7056049709e..dd36e10efa65 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -3128,6 +3128,7 @@ static void show_pte(unsigned long addr)
>  	struct task_struct *tsk = NULL;
>  	struct mm_struct *mm;
>  	pgd_t *pgdp, *pgdir;
> +	p4d_t *p4dp;
>  	pud_t *pudp;
>  	pmd_t *pmdp;
>  	pte_t *ptep;
> @@ -3172,7 +3173,21 @@ static void show_pte(unsigned long addr)
>  	}
>  	printf("pgdp @ 0x%px = 0x%016lx\n", pgdp, pgd_val(*pgdp));
>  
> -	pudp = pud_offset(pgdp, addr);
> +	p4dp = p4d_offset(pgdp, addr);
> +
> +	if (p4d_none(*p4dp)) {
> +		printf("No valid P4D\n");
> +		return;
> +	}
> +
> +	if (p4d_is_leaf(*p4dp)) {
> +		format_pte(p4dp, p4d_val(*p4dp));
> +		return;
> +	}
> +
> +	printf("p4dp @ 0x%px = 0x%016lx\n", p4dp, p4d_val(*p4dp));
> +
> +	pudp = pud_offset(p4dp, addr);
>  
>  	if (pud_none(*pudp)) {
>  		printf("No valid PUD\n");
> -- 
> 2.24.0
> 

-- 
Sincerely yours,
Mike.