root/arch/powerpc/include/asm/book3s/64/hash-64k.h

INCLUDED FROM

DEFINITIONS

1. __real_pte
2. __rpte_to_hidx
3. pte_set_hidx
4. hash__remap_4k_pfn
5. get_hpte_slot_array
6. hpte_valid
7. hpte_hash_index
8. mark_hpte_slot_valid
9. hash__pmd_trans_huge
10. hash__pmd_same
11. hash__pmd_mkhuge
12. hash__pmd_mkdevmap

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_POWERPC_BOOK3S_64_HASH_64K_H
   3 #define _ASM_POWERPC_BOOK3S_64_HASH_64K_H
   4 
   5 #define H_PTE_INDEX_SIZE   8  // size: 8B <<  8 = 2KB, maps 2^8  x 64KB = 16MB
   6 #define H_PMD_INDEX_SIZE  10  // size: 8B << 10 = 8KB, maps 2^10 x 16MB = 16GB
   7 #define H_PUD_INDEX_SIZE  10  // size: 8B << 10 = 8KB, maps 2^10 x 16GB = 16TB
   8 #define H_PGD_INDEX_SIZE   8  // size: 8B <<  8 = 2KB, maps 2^8  x 16TB =  4PB
   9 
  10 
  11 /*
  12  * Each context is 512TB size. SLB miss for first context/default context
  13  * is handled in the hotpath.
  14  */
  15 #define MAX_EA_BITS_PER_CONTEXT         49
  16 #define REGION_SHIFT            MAX_EA_BITS_PER_CONTEXT
  17 
  18 /*
  19  * We use one context for each MAP area.
  20  */
  21 #define H_KERN_MAP_SIZE         (1UL << MAX_EA_BITS_PER_CONTEXT)
  22 
  23 /*
  24  * Define the address range of the kernel non-linear virtual area
  25  * 2PB
  26  */
  27 #define H_KERN_VIRT_START       ASM_CONST(0xc008000000000000)
  28 
  29 /*
  30  * 64k aligned address free up few of the lower bits of RPN for us
  31  * We steal that here. For more deatils look at pte_pfn/pfn_pte()
  32  */
  33 #define H_PAGE_COMBO    _RPAGE_RPN0 /* this is a combo 4k page */
  34 #define H_PAGE_4K_PFN   _RPAGE_RPN1 /* PFN is for a single 4k page */
  35 #define H_PAGE_BUSY     _RPAGE_RPN44     /* software: PTE & hash are busy */
  36 #define H_PAGE_HASHPTE  _RPAGE_RPN43    /* PTE has associated HPTE */
  37 
  38 /* memory key bits. */
  39 #define H_PTE_PKEY_BIT0 _RPAGE_RSV1
  40 #define H_PTE_PKEY_BIT1 _RPAGE_RSV2
  41 #define H_PTE_PKEY_BIT2 _RPAGE_RSV3
  42 #define H_PTE_PKEY_BIT3 _RPAGE_RSV4
  43 #define H_PTE_PKEY_BIT4 _RPAGE_RSV5
  44 
  45 /*
  46  * We need to differentiate between explicit huge page and THP huge
  47  * page, since THP huge page also need to track real subpage details
  48  */
  49 #define H_PAGE_THP_HUGE  H_PAGE_4K_PFN
  50 
  51 /* PTE flags to conserve for HPTE identification */
  52 #define _PAGE_HPTEFLAGS (H_PAGE_BUSY | H_PAGE_HASHPTE | H_PAGE_COMBO)
  53 /*
  54  * We use a 2K PTE page fragment and another 2K for storing
  55  * real_pte_t hash index
  56  * 8 bytes per each pte entry and another 8 bytes for storing
  57  * slot details.
  58  */
  59 #define H_PTE_FRAG_SIZE_SHIFT  (H_PTE_INDEX_SIZE + 3 + 1)
  60 #define H_PTE_FRAG_NR   (PAGE_SIZE >> H_PTE_FRAG_SIZE_SHIFT)
  61 
  62 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLB_PAGE)
  63 #define H_PMD_FRAG_SIZE_SHIFT  (H_PMD_INDEX_SIZE + 3 + 1)
  64 #else
  65 #define H_PMD_FRAG_SIZE_SHIFT  (H_PMD_INDEX_SIZE + 3)
  66 #endif
  67 #define H_PMD_FRAG_NR   (PAGE_SIZE >> H_PMD_FRAG_SIZE_SHIFT)
  68 
  69 #ifndef __ASSEMBLY__
  70 #include <asm/errno.h>
  71 
  72 /*
  73  * With 64K pages on hash table, we have a special PTE format that
  74  * uses a second "half" of the page table to encode sub-page information
  75  * in order to deal with 64K made of 4K HW pages. Thus we override the
  76  * generic accessors and iterators here
  77  */
  78 #define __real_pte __real_pte
  79 static inline real_pte_t __real_pte(pte_t pte, pte_t *ptep, int offset)
  80 {
  81         real_pte_t rpte;
  82         unsigned long *hidxp;
  83 
  84         rpte.pte = pte;
  85 
  86         /*
  87          * Ensure that we do not read the hidx before we read the PTE. Because
  88          * the writer side is expected to finish writing the hidx first followed
  89          * by the PTE, by using smp_wmb(). pte_set_hash_slot() ensures that.
  90          */
  91         smp_rmb();
  92 
  93         hidxp = (unsigned long *)(ptep + offset);
  94         rpte.hidx = *hidxp;
  95         return rpte;
  96 }
  97 
  98 /*
  99  * shift the hidx representation by one-modulo-0xf; i.e hidx 0 is respresented
 100  * as 1, 1 as 2,... , and 0xf as 0.  This convention lets us represent a
 101  * invalid hidx 0xf with a 0x0 bit value. PTEs are anyway zero'd when
 102  * allocated. We dont have to zero them gain; thus save on the initialization.
 103  */
 104 #define HIDX_UNSHIFT_BY_ONE(x) ((x + 0xfUL) & 0xfUL) /* shift backward by one */
 105 #define HIDX_SHIFT_BY_ONE(x) ((x + 0x1UL) & 0xfUL)   /* shift forward by one */
 106 #define HIDX_BITS(x, index)  (x << (index << 2))
 107 #define BITS_TO_HIDX(x, index)  ((x >> (index << 2)) & 0xfUL)
 108 #define INVALID_RPTE_HIDX  0x0UL
 109 
 110 static inline unsigned long __rpte_to_hidx(real_pte_t rpte, unsigned long index)
 111 {
 112         return HIDX_UNSHIFT_BY_ONE(BITS_TO_HIDX(rpte.hidx, index));
 113 }
 114 
 115 /*
 116  * Commit the hidx and return PTE bits that needs to be modified. The caller is
 117  * expected to modify the PTE bits accordingly and commit the PTE to memory.
 118  */
 119 static inline unsigned long pte_set_hidx(pte_t *ptep, real_pte_t rpte,
 120                                          unsigned int subpg_index,
 121                                          unsigned long hidx, int offset)
 122 {
 123         unsigned long *hidxp = (unsigned long *)(ptep + offset);
 124 
 125         rpte.hidx &= ~HIDX_BITS(0xfUL, subpg_index);
 126         *hidxp = rpte.hidx  | HIDX_BITS(HIDX_SHIFT_BY_ONE(hidx), subpg_index);
 127 
 128         /*
 129          * Anyone reading PTE must ensure hidx bits are read after reading the
 130          * PTE by using the read-side barrier smp_rmb(). __real_pte() can be
 131          * used for that.
 132          */
 133         smp_wmb();
 134 
 135         /* No PTE bits to be modified, return 0x0UL */
 136         return 0x0UL;
 137 }
 138 
 139 #define __rpte_to_pte(r)        ((r).pte)
 140 extern bool __rpte_sub_valid(real_pte_t rpte, unsigned long index);
 141 /*
 142  * Trick: we set __end to va + 64k, which happens works for
 143  * a 16M page as well as we want only one iteration
 144  */
 145 #define pte_iterate_hashed_subpages(rpte, psize, vpn, index, shift)     \
 146         do {                                                            \
 147                 unsigned long __end = vpn + (1UL << (PAGE_SHIFT - VPN_SHIFT));  \
 148                 unsigned __split = (psize == MMU_PAGE_4K ||             \
 149                                     psize == MMU_PAGE_64K_AP);          \
 150                 shift = mmu_psize_defs[psize].shift;                    \
 151                 for (index = 0; vpn < __end; index++,                   \
 152                              vpn += (1L << (shift - VPN_SHIFT))) {      \
 153                 if (!__split || __rpte_sub_valid(rpte, index))
 154 
 155 #define pte_iterate_hashed_end()  } } while(0)
 156 
 157 #define pte_pagesize_index(mm, addr, pte)       \
 158         (((pte) & H_PAGE_COMBO)? MMU_PAGE_4K: MMU_PAGE_64K)
 159 
 160 extern int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
 161                            unsigned long pfn, unsigned long size, pgprot_t);
 162 static inline int hash__remap_4k_pfn(struct vm_area_struct *vma, unsigned long addr,
 163                                  unsigned long pfn, pgprot_t prot)
 164 {
 165         if (pfn > (PTE_RPN_MASK >> PAGE_SHIFT)) {
 166                 WARN(1, "remap_4k_pfn called with wrong pfn value\n");
 167                 return -EINVAL;
 168         }
 169         return remap_pfn_range(vma, addr, pfn, PAGE_SIZE,
 170                                __pgprot(pgprot_val(prot) | H_PAGE_4K_PFN));
 171 }
 172 
 173 #define H_PTE_TABLE_SIZE        PTE_FRAG_SIZE
 174 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined (CONFIG_HUGETLB_PAGE)
 175 #define H_PMD_TABLE_SIZE        ((sizeof(pmd_t) << PMD_INDEX_SIZE) + \
 176                                  (sizeof(unsigned long) << PMD_INDEX_SIZE))
 177 #else
 178 #define H_PMD_TABLE_SIZE        (sizeof(pmd_t) << PMD_INDEX_SIZE)
 179 #endif
 180 #ifdef CONFIG_HUGETLB_PAGE
 181 #define H_PUD_TABLE_SIZE        ((sizeof(pud_t) << PUD_INDEX_SIZE) +    \
 182                                  (sizeof(unsigned long) << PUD_INDEX_SIZE))
 183 #else
 184 #define H_PUD_TABLE_SIZE        (sizeof(pud_t) << PUD_INDEX_SIZE)
 185 #endif
 186 #define H_PGD_TABLE_SIZE        (sizeof(pgd_t) << PGD_INDEX_SIZE)
 187 
 188 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 189 static inline char *get_hpte_slot_array(pmd_t *pmdp)
 190 {
 191         /*
 192          * The hpte hindex is stored in the pgtable whose address is in the
 193          * second half of the PMD
 194          *
 195          * Order this load with the test for pmd_trans_huge in the caller
 196          */
 197         smp_rmb();
 198         return *(char **)(pmdp + PTRS_PER_PMD);
 199 
 200 
 201 }
 202 /*
 203  * The linux hugepage PMD now include the pmd entries followed by the address
 204  * to the stashed pgtable_t. The stashed pgtable_t contains the hpte bits.
 205  * [ 000 | 1 bit secondary | 3 bit hidx | 1 bit valid]. We use one byte per
 206  * each HPTE entry. With 16MB hugepage and 64K HPTE we need 256 entries and
 207  * with 4K HPTE we need 4096 entries. Both will fit in a 4K pgtable_t.
 208  *
 209  * The top three bits are intentionally left as zero. This memory location
 210  * are also used as normal page PTE pointers. So if we have any pointers
 211  * left around while we collapse a hugepage, we need to make sure
 212  * _PAGE_PRESENT bit of that is zero when we look at them
 213  */
 214 static inline unsigned int hpte_valid(unsigned char *hpte_slot_array, int index)
 215 {
 216         return hpte_slot_array[index] & 0x1;
 217 }
 218 
 219 static inline unsigned int hpte_hash_index(unsigned char *hpte_slot_array,
 220                                            int index)
 221 {
 222         return hpte_slot_array[index] >> 1;
 223 }
 224 
 225 static inline void mark_hpte_slot_valid(unsigned char *hpte_slot_array,
 226                                         unsigned int index, unsigned int hidx)
 227 {
 228         hpte_slot_array[index] = (hidx << 1) | 0x1;
 229 }
 230 
 231 /*
 232  *
 233  * For core kernel code by design pmd_trans_huge is never run on any hugetlbfs
 234  * page. The hugetlbfs page table walking and mangling paths are totally
 235  * separated form the core VM paths and they're differentiated by
 236  *  VM_HUGETLB being set on vm_flags well before any pmd_trans_huge could run.
 237  *
 238  * pmd_trans_huge() is defined as false at build time if
 239  * CONFIG_TRANSPARENT_HUGEPAGE=n to optimize away code blocks at build
 240  * time in such case.
 241  *
 242  * For ppc64 we need to differntiate from explicit hugepages from THP, because
 243  * for THP we also track the subpage details at the pmd level. We don't do
 244  * that for explicit huge pages.
 245  *
 246  */
 247 static inline int hash__pmd_trans_huge(pmd_t pmd)
 248 {
 249         return !!((pmd_val(pmd) & (_PAGE_PTE | H_PAGE_THP_HUGE | _PAGE_DEVMAP)) ==
 250                   (_PAGE_PTE | H_PAGE_THP_HUGE));
 251 }
 252 
 253 static inline int hash__pmd_same(pmd_t pmd_a, pmd_t pmd_b)
 254 {
 255         return (((pmd_raw(pmd_a) ^ pmd_raw(pmd_b)) & ~cpu_to_be64(_PAGE_HPTEFLAGS)) == 0);
 256 }
 257 
 258 static inline pmd_t hash__pmd_mkhuge(pmd_t pmd)
 259 {
 260         return __pmd(pmd_val(pmd) | (_PAGE_PTE | H_PAGE_THP_HUGE));
 261 }
 262 
 263 extern unsigned long hash__pmd_hugepage_update(struct mm_struct *mm,
 264                                            unsigned long addr, pmd_t *pmdp,
 265                                            unsigned long clr, unsigned long set);
 266 extern pmd_t hash__pmdp_collapse_flush(struct vm_area_struct *vma,
 267                                    unsigned long address, pmd_t *pmdp);
 268 extern void hash__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
 269                                          pgtable_t pgtable);
 270 extern pgtable_t hash__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp);
 271 extern pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm,
 272                                        unsigned long addr, pmd_t *pmdp);
 273 extern int hash__has_transparent_hugepage(void);
 274 #endif /*  CONFIG_TRANSPARENT_HUGEPAGE */
 275 
 276 static inline pmd_t hash__pmd_mkdevmap(pmd_t pmd)
 277 {
 278         return __pmd(pmd_val(pmd) | (_PAGE_PTE | H_PAGE_THP_HUGE | _PAGE_DEVMAP));
 279 }
 280 
 281 #endif  /* __ASSEMBLY__ */
 282 
 283 #endif /* _ASM_POWERPC_BOOK3S_64_HASH_64K_H */