linux_dsm_epyc7002/arch/powerpc/mm/hugepage-hash64.c
Aneesh Kumar K.V 9ab3ac233a powerpc/mm/hash: Clear the invalid slot information correctly
We can get a hash pte fault with 4k base page size and find the pte
already inserted with 64K base page size. In that case we need to clear
the existing slot information from the old pte. Fix this correctly

With THP, we also clear the slot information with respect to all
the 64K hash pte mapping that 16MB page. They are all invalid
now. This make sure we don't find the slot valid when we fault with
4k base page size. Finding the slot valid should not result in any wrong
behavior because we do check again in hash page table for the validity.
But we can avoid that check completely.

Fixes: a43c0eb836 ("powerpc/mm: Convert 4k hash insert to C")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2016-02-22 19:27:39 +11:00

186 lines
5.1 KiB
C

/*
* Copyright IBM Corporation, 2013
* Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2.1 of the GNU Lesser General Public License
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
*/
/*
* PPC64 THP Support for hash based MMUs
*/
#include <linux/mm.h>
#include <asm/machdep.h>
int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
pmd_t *pmdp, unsigned long trap, unsigned long flags,
int ssize, unsigned int psize)
{
unsigned int index, valid;
unsigned char *hpte_slot_array;
unsigned long rflags, pa, hidx;
unsigned long old_pmd, new_pmd;
int ret, lpsize = MMU_PAGE_16M;
unsigned long vpn, hash, shift, slot;
/*
* atomically mark the linux large page PMD busy and dirty
*/
do {
pmd_t pmd = READ_ONCE(*pmdp);
old_pmd = pmd_val(pmd);
/* If PMD busy, retry the access */
if (unlikely(old_pmd & _PAGE_BUSY))
return 0;
/* If PMD permissions don't match, take page fault */
if (unlikely(access & ~old_pmd))
return 1;
/*
* Try to lock the PTE, add ACCESSED and DIRTY if it was
* a write access
*/
new_pmd = old_pmd | _PAGE_BUSY | _PAGE_ACCESSED;
if (access & _PAGE_RW)
new_pmd |= _PAGE_DIRTY;
} while (old_pmd != __cmpxchg_u64((unsigned long *)pmdp,
old_pmd, new_pmd));
rflags = htab_convert_pte_flags(new_pmd);
#if 0
if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
/*
* No CPU has hugepages but lacks no execute, so we
* don't need to worry about that case
*/
rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
}
#endif
/*
* Find the slot index details for this ea, using base page size.
*/
shift = mmu_psize_defs[psize].shift;
index = (ea & ~HPAGE_PMD_MASK) >> shift;
BUG_ON(index >= PTE_FRAG_SIZE);
vpn = hpt_vpn(ea, vsid, ssize);
hpte_slot_array = get_hpte_slot_array(pmdp);
if (psize == MMU_PAGE_4K) {
/*
* invalidate the old hpte entry if we have that mapped via 64K
* base page size. This is because demote_segment won't flush
* hash page table entries.
*/
if ((old_pmd & _PAGE_HASHPTE) && !(old_pmd & _PAGE_COMBO)) {
flush_hash_hugepage(vsid, ea, pmdp, MMU_PAGE_64K,
ssize, flags);
/*
* With THP, we also clear the slot information with
* respect to all the 64K hash pte mapping the 16MB
* page. They are all invalid now. This make sure we
* don't find the slot valid when we fault with 4k
* base page size.
*
*/
memset(hpte_slot_array, 0, PTE_FRAG_SIZE);
}
}
valid = hpte_valid(hpte_slot_array, index);
if (valid) {
/* update the hpte bits */
hash = hpt_hash(vpn, shift, ssize);
hidx = hpte_hash_index(hpte_slot_array, index);
if (hidx & _PTEIDX_SECONDARY)
hash = ~hash;
slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
slot += hidx & _PTEIDX_GROUP_IX;
ret = ppc_md.hpte_updatepp(slot, rflags, vpn,
psize, lpsize, ssize, flags);
/*
* We failed to update, try to insert a new entry.
*/
if (ret == -1) {
/*
* large pte is marked busy, so we can be sure
* nobody is looking at hpte_slot_array. hence we can
* safely update this here.
*/
valid = 0;
hpte_slot_array[index] = 0;
}
}
if (!valid) {
unsigned long hpte_group;
hash = hpt_hash(vpn, shift, ssize);
/* insert new entry */
pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT;
new_pmd |= _PAGE_HASHPTE;
repeat:
hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
/* Insert into the hash table, primary slot */
slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
psize, lpsize, ssize);
/*
* Primary is full, try the secondary
*/
if (unlikely(slot == -1)) {
hpte_group = ((~hash & htab_hash_mask) *
HPTES_PER_GROUP) & ~0x7UL;
slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
rflags, HPTE_V_SECONDARY,
psize, lpsize, ssize);
if (slot == -1) {
if (mftb() & 0x1)
hpte_group = ((hash & htab_hash_mask) *
HPTES_PER_GROUP) & ~0x7UL;
ppc_md.hpte_remove(hpte_group);
goto repeat;
}
}
/*
* Hypervisor failure. Restore old pmd and return -1
* similar to __hash_page_*
*/
if (unlikely(slot == -2)) {
*pmdp = __pmd(old_pmd);
hash_failure_debug(ea, access, vsid, trap, ssize,
psize, lpsize, old_pmd);
return -1;
}
/*
* large pte is marked busy, so we can be sure
* nobody is looking at hpte_slot_array. hence we can
* safely update this here.
*/
mark_hpte_slot_valid(hpte_slot_array, index, slot);
}
/*
* Mark the pte with _PAGE_COMBO, if we are trying to hash it with
* base page size 4k.
*/
if (psize == MMU_PAGE_4K)
new_pmd |= _PAGE_COMBO;
/*
* The hpte valid is stored in the pgtable whose address is in the
* second half of the PMD. Order this against clearing of the busy bit in
* huge pmd.
*/
smp_wmb();
*pmdp = __pmd(new_pmd & ~_PAGE_BUSY);
return 0;
}