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1c343f7b0e
linux/arch/s390/mm/pgtable.c
Christian Borntraeger 1c343f7b0e KVM: s390/mm: Fix CMMA reset during reboot 
commit 1e133ab296 ("s390/mm: split arch/s390/mm/pgtable.c") factored
out the page table handling code from __gmap_zap and  __s390_reset_cmma
into ptep_zap_unused and added a simple flag that tells which one of the
function (reset or not) is to be made. This also changed the behaviour,
as it also zaps unused page table entries on reset.
Turns out that this is wrong as s390_reset_cmma uses the page walker,
which DOES NOT take the ptl lock.

The most simple fix is to not do the zapping part on reset (which uses
the walker)

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Fixes: 1e133ab296 ("s390/mm: split arch/s390/mm/pgtable.c")
Cc: stable@vger.kernel.org # 4.6+
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-06-13 15:58:09 +02:00

583 lines
14 KiB
C
Raw Blame History

/*
* Copyright IBM Corp. 2007, 2011
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/swapops.h>
#include <linux/sysctl.h>
#include <linux/ksm.h>
#include <linux/mman.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
static inline pte_t ptep_flush_direct(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
int active, count;
pte_t old;
old = *ptep;
if (unlikely(pte_val(old) & _PAGE_INVALID))
return old;
active = (mm == current->active_mm) ? 1 : 0;
count = atomic_add_return(0x10000, &mm->context.attach_count);
if (MACHINE_HAS_TLB_LC && (count & 0xffff) <= active &&
cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
__ptep_ipte_local(addr, ptep);
else
__ptep_ipte(addr, ptep);
atomic_sub(0x10000, &mm->context.attach_count);
return old;
}
static inline pte_t ptep_flush_lazy(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
int active, count;
pte_t old;
old = *ptep;
if (unlikely(pte_val(old) & _PAGE_INVALID))
return old;
active = (mm == current->active_mm) ? 1 : 0;
count = atomic_add_return(0x10000, &mm->context.attach_count);
if ((count & 0xffff) <= active) {
pte_val(*ptep) |= _PAGE_INVALID;
mm->context.flush_mm = 1;
} else
__ptep_ipte(addr, ptep);
atomic_sub(0x10000, &mm->context.attach_count);
return old;
}
static inline pgste_t pgste_get_lock(pte_t *ptep)
{
unsigned long new = 0;
#ifdef CONFIG_PGSTE
unsigned long old;
preempt_disable();
asm(
" lg %0,%2\n"
"0: lgr %1,%0\n"
" nihh %0,0xff7f\n" /* clear PCL bit in old */
" oihh %1,0x0080\n" /* set PCL bit in new */
" csg %0,%1,%2\n"
" jl 0b\n"
: "=&d" (old), "=&d" (new), "=Q" (ptep[PTRS_PER_PTE])
: "Q" (ptep[PTRS_PER_PTE]) : "cc", "memory");
#endif
return __pgste(new);
}
static inline void pgste_set_unlock(pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
asm(
" nihh %1,0xff7f\n" /* clear PCL bit */
" stg %1,%0\n"
: "=Q" (ptep[PTRS_PER_PTE])
: "d" (pgste_val(pgste)), "Q" (ptep[PTRS_PER_PTE])
: "cc", "memory");
preempt_enable();
#endif
}
static inline pgste_t pgste_get(pte_t *ptep)
{
unsigned long pgste = 0;
#ifdef CONFIG_PGSTE
pgste = *(unsigned long *)(ptep + PTRS_PER_PTE);
#endif
return __pgste(pgste);
}
static inline void pgste_set(pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
*(pgste_t *)(ptep + PTRS_PER_PTE) = pgste;
#endif
}
static inline pgste_t pgste_update_all(pte_t pte, pgste_t pgste,
struct mm_struct *mm)
{
#ifdef CONFIG_PGSTE
unsigned long address, bits, skey;
if (!mm_use_skey(mm) || pte_val(pte) & _PAGE_INVALID)
return pgste;
address = pte_val(pte) & PAGE_MASK;
skey = (unsigned long) page_get_storage_key(address);
bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
/* Transfer page changed & referenced bit to guest bits in pgste */
pgste_val(pgste) |= bits << 48; /* GR bit & GC bit */
/* Copy page access key and fetch protection bit to pgste */
pgste_val(pgste) &= ~(PGSTE_ACC_BITS | PGSTE_FP_BIT);
pgste_val(pgste) |= (skey & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
#endif
return pgste;
}
static inline void pgste_set_key(pte_t *ptep, pgste_t pgste, pte_t entry,
struct mm_struct *mm)
{
#ifdef CONFIG_PGSTE
unsigned long address;
unsigned long nkey;
if (!mm_use_skey(mm) || pte_val(entry) & _PAGE_INVALID)
return;
VM_BUG_ON(!(pte_val(*ptep) & _PAGE_INVALID));
address = pte_val(entry) & PAGE_MASK;
/*
* Set page access key and fetch protection bit from pgste.
* The guest C/R information is still in the PGSTE, set real
* key C/R to 0.
*/
nkey = (pgste_val(pgste) & (PGSTE_ACC_BITS | PGSTE_FP_BIT)) >> 56;
nkey |= (pgste_val(pgste) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 48;
page_set_storage_key(address, nkey, 0);
#endif
}
static inline pgste_t pgste_set_pte(pte_t *ptep, pgste_t pgste, pte_t entry)
{
#ifdef CONFIG_PGSTE
if ((pte_val(entry) & _PAGE_PRESENT) &&
(pte_val(entry) & _PAGE_WRITE) &&
!(pte_val(entry) & _PAGE_INVALID)) {
if (!MACHINE_HAS_ESOP) {
/*
* Without enhanced suppression-on-protection force
* the dirty bit on for all writable ptes.
*/
pte_val(entry) |= _PAGE_DIRTY;
pte_val(entry) &= ~_PAGE_PROTECT;
}
if (!(pte_val(entry) & _PAGE_PROTECT))
/* This pte allows write access, set user-dirty */
pgste_val(pgste) |= PGSTE_UC_BIT;
}
#endif
*ptep = entry;
return pgste;
}
static inline pgste_t pgste_ipte_notify(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
if (pgste_val(pgste) & PGSTE_IN_BIT) {
pgste_val(pgste) &= ~PGSTE_IN_BIT;
ptep_notify(mm, addr, ptep);
}
#endif
return pgste;
}
static inline pgste_t ptep_xchg_start(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
pgste_t pgste = __pgste(0);
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_ipte_notify(mm, addr, ptep, pgste);
}
return pgste;
}
static inline void ptep_xchg_commit(struct mm_struct *mm,
unsigned long addr, pte_t *ptep,
pgste_t pgste, pte_t old, pte_t new)
{
if (mm_has_pgste(mm)) {
if (pte_val(old) & _PAGE_INVALID)
pgste_set_key(ptep, pgste, new, mm);
if (pte_val(new) & _PAGE_INVALID) {
pgste = pgste_update_all(old, pgste, mm);
if ((pgste_val(pgste) & _PGSTE_GPS_USAGE_MASK) ==
_PGSTE_GPS_USAGE_UNUSED)
pte_val(old) |= _PAGE_UNUSED;
}
pgste = pgste_set_pte(ptep, pgste, new);
pgste_set_unlock(ptep, pgste);
} else {
*ptep = new;
}
}
pte_t ptep_xchg_direct(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t new)
{
pgste_t pgste;
pte_t old;
pgste = ptep_xchg_start(mm, addr, ptep);
old = ptep_flush_direct(mm, addr, ptep);
ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
return old;
}
EXPORT_SYMBOL(ptep_xchg_direct);
pte_t ptep_xchg_lazy(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t new)
{
pgste_t pgste;
pte_t old;
pgste = ptep_xchg_start(mm, addr, ptep);
old = ptep_flush_lazy(mm, addr, ptep);
ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
return old;
}
EXPORT_SYMBOL(ptep_xchg_lazy);
pte_t ptep_modify_prot_start(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
pgste_t pgste;
pte_t old;
pgste = ptep_xchg_start(mm, addr, ptep);
old = ptep_flush_lazy(mm, addr, ptep);
if (mm_has_pgste(mm)) {
pgste = pgste_update_all(old, pgste, mm);
pgste_set(ptep, pgste);
}
return old;
}
EXPORT_SYMBOL(ptep_modify_prot_start);
void ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
pgste_t pgste;
if (mm_has_pgste(mm)) {
pgste = pgste_get(ptep);
pgste_set_key(ptep, pgste, pte, mm);
pgste = pgste_set_pte(ptep, pgste, pte);
pgste_set_unlock(ptep, pgste);
} else {
*ptep = pte;
}
}
EXPORT_SYMBOL(ptep_modify_prot_commit);
static inline pmd_t pmdp_flush_direct(struct mm_struct *mm,
unsigned long addr, pmd_t *pmdp)
{
int active, count;
pmd_t old;
old = *pmdp;
if (pmd_val(old) & _SEGMENT_ENTRY_INVALID)
return old;
if (!MACHINE_HAS_IDTE) {
__pmdp_csp(pmdp);
return old;
}
active = (mm == current->active_mm) ? 1 : 0;
count = atomic_add_return(0x10000, &mm->context.attach_count);
if (MACHINE_HAS_TLB_LC && (count & 0xffff) <= active &&
cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
__pmdp_idte_local(addr, pmdp);
else
__pmdp_idte(addr, pmdp);
atomic_sub(0x10000, &mm->context.attach_count);
return old;
}
static inline pmd_t pmdp_flush_lazy(struct mm_struct *mm,
unsigned long addr, pmd_t *pmdp)
{
int active, count;
pmd_t old;
old = *pmdp;
if (pmd_val(old) & _SEGMENT_ENTRY_INVALID)
return old;
active = (mm == current->active_mm) ? 1 : 0;
count = atomic_add_return(0x10000, &mm->context.attach_count);
if ((count & 0xffff) <= active) {
pmd_val(*pmdp) |= _SEGMENT_ENTRY_INVALID;
mm->context.flush_mm = 1;
} else if (MACHINE_HAS_IDTE)
__pmdp_idte(addr, pmdp);
else
__pmdp_csp(pmdp);
atomic_sub(0x10000, &mm->context.attach_count);
return old;
}
pmd_t pmdp_xchg_direct(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t new)
{
pmd_t old;
old = pmdp_flush_direct(mm, addr, pmdp);
*pmdp = new;
return old;
}
EXPORT_SYMBOL(pmdp_xchg_direct);
pmd_t pmdp_xchg_lazy(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t new)
{
pmd_t old;
old = pmdp_flush_lazy(mm, addr, pmdp);
*pmdp = new;
return old;
}
EXPORT_SYMBOL(pmdp_xchg_lazy);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
pgtable_t pgtable)
{
struct list_head *lh = (struct list_head *) pgtable;
assert_spin_locked(pmd_lockptr(mm, pmdp));
/* FIFO */
if (!pmd_huge_pte(mm, pmdp))
INIT_LIST_HEAD(lh);
else
list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
pmd_huge_pte(mm, pmdp) = pgtable;
}
pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
struct list_head *lh;
pgtable_t pgtable;
pte_t *ptep;
assert_spin_locked(pmd_lockptr(mm, pmdp));
/* FIFO */
pgtable = pmd_huge_pte(mm, pmdp);
lh = (struct list_head *) pgtable;
if (list_empty(lh))
pmd_huge_pte(mm, pmdp) = NULL;
else {
pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
list_del(lh);
}
ptep = (pte_t *) pgtable;
pte_val(*ptep) = _PAGE_INVALID;
ptep++;
pte_val(*ptep) = _PAGE_INVALID;
return pgtable;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#ifdef CONFIG_PGSTE
void ptep_set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t entry)
{
pgste_t pgste;
/* the mm_has_pgste() check is done in set_pte_at() */
pgste = pgste_get_lock(ptep);
pgste_val(pgste) &= ~_PGSTE_GPS_ZERO;
pgste_set_key(ptep, pgste, entry, mm);
pgste = pgste_set_pte(ptep, pgste, entry);
pgste_set_unlock(ptep, pgste);
}
void ptep_set_notify(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
pgste_t pgste;
pgste = pgste_get_lock(ptep);
pgste_val(pgste) |= PGSTE_IN_BIT;
pgste_set_unlock(ptep, pgste);
}
static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry)
{
if (!non_swap_entry(entry))
dec_mm_counter(mm, MM_SWAPENTS);
else if (is_migration_entry(entry)) {
struct page *page = migration_entry_to_page(entry);
dec_mm_counter(mm, mm_counter(page));
}
free_swap_and_cache(entry);
}
void ptep_zap_unused(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, int reset)
{
unsigned long pgstev;
pgste_t pgste;
pte_t pte;
/* Zap unused and logically-zero pages */
pgste = pgste_get_lock(ptep);
pgstev = pgste_val(pgste);
pte = *ptep;
if (!reset && pte_swap(pte) &&
((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED ||
(pgstev & _PGSTE_GPS_ZERO))) {
ptep_zap_swap_entry(mm, pte_to_swp_entry(pte));
pte_clear(mm, addr, ptep);
}
if (reset)
pgste_val(pgste) &= ~_PGSTE_GPS_USAGE_MASK;
pgste_set_unlock(ptep, pgste);
}
void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
unsigned long ptev;
pgste_t pgste;
/* Clear storage key */
pgste = pgste_get_lock(ptep);
pgste_val(pgste) &= ~(PGSTE_ACC_BITS | PGSTE_FP_BIT |
PGSTE_GR_BIT | PGSTE_GC_BIT);
ptev = pte_val(*ptep);
if (!(ptev & _PAGE_INVALID) && (ptev & _PAGE_WRITE))
page_set_storage_key(ptev & PAGE_MASK, PAGE_DEFAULT_KEY, 1);
pgste_set_unlock(ptep, pgste);
}
/*
* Test and reset if a guest page is dirty
*/
bool test_and_clear_guest_dirty(struct mm_struct *mm, unsigned long addr)
{
spinlock_t *ptl;
pgste_t pgste;
pte_t *ptep;
pte_t pte;
bool dirty;
ptep = get_locked_pte(mm, addr, &ptl);
if (unlikely(!ptep))
return false;
pgste = pgste_get_lock(ptep);
dirty = !!(pgste_val(pgste) & PGSTE_UC_BIT);
pgste_val(pgste) &= ~PGSTE_UC_BIT;
pte = *ptep;
if (dirty && (pte_val(pte) & _PAGE_PRESENT)) {
pgste = pgste_ipte_notify(mm, addr, ptep, pgste);
__ptep_ipte(addr, ptep);
if (MACHINE_HAS_ESOP || !(pte_val(pte) & _PAGE_WRITE))
pte_val(pte) |= _PAGE_PROTECT;
else
pte_val(pte) |= _PAGE_INVALID;
*ptep = pte;
}
pgste_set_unlock(ptep, pgste);
spin_unlock(ptl);
return dirty;
}
EXPORT_SYMBOL_GPL(test_and_clear_guest_dirty);
int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
unsigned char key, bool nq)
{
unsigned long keyul;
spinlock_t *ptl;
pgste_t old, new;
pte_t *ptep;
down_read(&mm->mmap_sem);
ptep = get_locked_pte(mm, addr, &ptl);
if (unlikely(!ptep)) {
up_read(&mm->mmap_sem);
return -EFAULT;
}
new = old = pgste_get_lock(ptep);
pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |
PGSTE_ACC_BITS | PGSTE_FP_BIT);
keyul = (unsigned long) key;
pgste_val(new) |= (keyul & (_PAGE_CHANGED | _PAGE_REFERENCED)) << 48;
pgste_val(new) |= (keyul & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
if (!(pte_val(*ptep) & _PAGE_INVALID)) {
unsigned long address, bits, skey;
address = pte_val(*ptep) & PAGE_MASK;
skey = (unsigned long) page_get_storage_key(address);
bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
skey = key & (_PAGE_ACC_BITS | _PAGE_FP_BIT);
/* Set storage key ACC and FP */
page_set_storage_key(address, skey, !nq);
/* Merge host changed & referenced into pgste */
pgste_val(new) |= bits << 52;
}
/* changing the guest storage key is considered a change of the page */
if ((pgste_val(new) ^ pgste_val(old)) &
(PGSTE_ACC_BITS | PGSTE_FP_BIT | PGSTE_GR_BIT | PGSTE_GC_BIT))
pgste_val(new) |= PGSTE_UC_BIT;
pgste_set_unlock(ptep, new);
pte_unmap_unlock(ptep, ptl);
up_read(&mm->mmap_sem);
return 0;
}
EXPORT_SYMBOL(set_guest_storage_key);
unsigned char get_guest_storage_key(struct mm_struct *mm, unsigned long addr)
{
unsigned char key;
spinlock_t *ptl;
pgste_t pgste;
pte_t *ptep;
down_read(&mm->mmap_sem);
ptep = get_locked_pte(mm, addr, &ptl);
if (unlikely(!ptep)) {
up_read(&mm->mmap_sem);
return -EFAULT;
}
pgste = pgste_get_lock(ptep);
if (pte_val(*ptep) & _PAGE_INVALID) {
key = (pgste_val(pgste) & PGSTE_ACC_BITS) >> 56;
key |= (pgste_val(pgste) & PGSTE_FP_BIT) >> 56;
key |= (pgste_val(pgste) & PGSTE_GR_BIT) >> 48;
key |= (pgste_val(pgste) & PGSTE_GC_BIT) >> 48;
} else {
key = page_get_storage_key(pte_val(*ptep) & PAGE_MASK);
/* Reflect guest's logical view, not physical */
if (pgste_val(pgste) & PGSTE_GR_BIT)
key |= _PAGE_REFERENCED;
if (pgste_val(pgste) & PGSTE_GC_BIT)
key |= _PAGE_CHANGED;
}
pgste_set_unlock(ptep, pgste);
pte_unmap_unlock(ptep, ptl);
up_read(&mm->mmap_sem);
return key;
}
EXPORT_SYMBOL(get_guest_storage_key);
#endif
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