Re: [PATCH] powerpc: add support for folded p4d page tables

[Christophe Leroy <christophe.leroy@c-s.fr>]

Mike Rapoport <rppt@kernel.org> a écrit :

> Any updates on this?

Checkpatch reported several points, see  
https://patchwork.ozlabs.org/patch/1206344/

Christophe

>
> 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.