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KVM: s390: allow sie enablement for multi-threaded programs 

Improve the code to upgrade the standard 2K page tables to 4K page tables
with PGSTEs to allow the operation to happen when the program is already
multi-threaded.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Martin Schwidefsky 2013-07-26 15:04:02 +02:00 committed by Paolo Bonzini
parent 663f4c61b8
commit 3eabaee998
4 changed files with 129 additions and 84 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/s390/include/asm/mmu.h
View File

@ -12,8 +12,6 @@ typedef struct {
unsigned long asce_bits;
unsigned long asce_limit;
unsigned long vdso_base;
/* Cloned contexts will be created with extended page tables. */
unsigned int alloc_pgste:1;
/* The mmu context has extended page tables. */
unsigned int has_pgste:1;
} mm_context_t;

19
arch/s390/include/asm/mmu_context.h
View File

@ -21,24 +21,7 @@ static inline int init_new_context(struct task_struct *tsk,
#ifdef CONFIG_64BIT
mm->context.asce_bits |= _ASCE_TYPE_REGION3;
#endif
if (current->mm && current->mm->context.alloc_pgste) {
/*
* alloc_pgste indicates, that any NEW context will be created
* with extended page tables. The old context is unchanged. The
* page table allocation and the page table operations will
* look at has_pgste to distinguish normal and extended page
* tables. The only way to create extended page tables is to
* set alloc_pgste and then create a new context (e.g. dup_mm).
* The page table allocation is called after init_new_context
* and if has_pgste is set, it will create extended page
* tables.
*/
mm->context.has_pgste = 1;
mm->context.alloc_pgste = 1;
} else {
mm->context.has_pgste = 0;
mm->context.alloc_pgste = 0;
}
mm->context.has_pgste = 0;
mm->context.asce_limit = STACK_TOP_MAX;
crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
return 0;

11
arch/s390/include/asm/pgtable.h
View File

@ -1361,6 +1361,17 @@ static inline pmd_t pmd_mkwrite(pmd_t pmd)
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLB_PAGE */
static inline void pmdp_flush_lazy(struct mm_struct *mm,
unsigned long address, pmd_t *pmdp)
{
int active = (mm == current->active_mm) ? 1 : 0;
if ((atomic_read(&mm->context.attach_count) & 0xffff) > active)
__pmd_idte(address, pmdp);
else
mm->context.flush_mm = 1;
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define __HAVE_ARCH_PGTABLE_DEPOSIT

181
arch/s390/mm/pgtable.c
View File

@ -731,6 +731,11 @@ void gmap_do_ipte_notify(struct mm_struct *mm, unsigned long addr, pte_t *pte)
spin_unlock(&gmap_notifier_lock);
}
static inline int page_table_with_pgste(struct page *page)
{
return atomic_read(&page->_mapcount) == 0;
}
static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,
unsigned long vmaddr)
{
@ -750,7 +755,7 @@ static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,
mp->vmaddr = vmaddr & PMD_MASK;
INIT_LIST_HEAD(&mp->mapper);
page->index = (unsigned long) mp;
atomic_set(&page->_mapcount, 3);
atomic_set(&page->_mapcount, 0);
table = (unsigned long *) page_to_phys(page);
clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2);
clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
@ -821,6 +826,11 @@ EXPORT_SYMBOL(set_guest_storage_key);
#else /* CONFIG_PGSTE */
static inline int page_table_with_pgste(struct page *page)
{
return 0;
}
static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,
unsigned long vmaddr)
{
@ -897,12 +907,12 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
struct page *page;
unsigned int bit, mask;
if (mm_has_pgste(mm)) {
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
if (page_table_with_pgste(page)) {
gmap_disconnect_pgtable(mm, table);
return page_table_free_pgste(table);
}
/* Free 1K/2K page table fragment of a 4K page */
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
bit = 1 << ((__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)));
spin_lock_bh(&mm->context.list_lock);
if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK)
@ -940,14 +950,14 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table)
unsigned int bit, mask;
mm = tlb->mm;
if (mm_has_pgste(mm)) {
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
if (page_table_with_pgste(page)) {
gmap_disconnect_pgtable(mm, table);
table = (unsigned long *) (__pa(table) | FRAG_MASK);
tlb_remove_table(tlb, table);
return;
}
bit = 1 << ((__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)));
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
spin_lock_bh(&mm->context.list_lock);
if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK)
list_del(&page->lru);
@ -1033,36 +1043,120 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void thp_split_vma(struct vm_area_struct *vma)
static inline void thp_split_vma(struct vm_area_struct *vma)
{
unsigned long addr;
struct page *page;
for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
page = follow_page(vma, addr, FOLL_SPLIT);
}
for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE)
follow_page(vma, addr, FOLL_SPLIT);
}
void thp_split_mm(struct mm_struct *mm)
static inline void thp_split_mm(struct mm_struct *mm)
{
struct vm_area_struct *vma = mm->mmap;
struct vm_area_struct *vma;
while (vma != NULL) {
for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
thp_split_vma(vma);
vma->vm_flags &= ~VM_HUGEPAGE;
vma->vm_flags |= VM_NOHUGEPAGE;
vma = vma->vm_next;
}
mm->def_flags |= VM_NOHUGEPAGE;
}
#else
static inline void thp_split_mm(struct mm_struct *mm)
{
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
static unsigned long page_table_realloc_pmd(struct mmu_gather *tlb,
struct mm_struct *mm, pud_t *pud,
unsigned long addr, unsigned long end)
{
unsigned long next, *table, *new;
struct page *page;
pmd_t *pmd;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
again:
if (pmd_none_or_clear_bad(pmd))
continue;
table = (unsigned long *) pmd_deref(*pmd);
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
if (page_table_with_pgste(page))
continue;
/* Allocate new page table with pgstes */
new = page_table_alloc_pgste(mm, addr);
if (!new) {
mm->context.has_pgste = 0;
continue;
}
spin_lock(&mm->page_table_lock);
if (likely((unsigned long *) pmd_deref(*pmd) == table)) {
/* Nuke pmd entry pointing to the "short" page table */
pmdp_flush_lazy(mm, addr, pmd);
pmd_clear(pmd);
/* Copy ptes from old table to new table */
memcpy(new, table, PAGE_SIZE/2);
clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
/* Establish new table */
pmd_populate(mm, pmd, (pte_t *) new);
/* Free old table with rcu, there might be a walker! */
page_table_free_rcu(tlb, table);
new = NULL;
}
spin_unlock(&mm->page_table_lock);
if (new) {
page_table_free_pgste(new);
goto again;
}
} while (pmd++, addr = next, addr != end);
return addr;
}
static unsigned long page_table_realloc_pud(struct mmu_gather *tlb,
struct mm_struct *mm, pgd_t *pgd,
unsigned long addr, unsigned long end)
{
unsigned long next;
pud_t *pud;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
next = page_table_realloc_pmd(tlb, mm, pud, addr, next);
} while (pud++, addr = next, addr != end);
return addr;
}
static void page_table_realloc(struct mmu_gather *tlb, struct mm_struct *mm,
unsigned long addr, unsigned long end)
{
unsigned long next;
pgd_t *pgd;
pgd = pgd_offset(mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
next = page_table_realloc_pud(tlb, mm, pgd, addr, next);
} while (pgd++, addr = next, addr != end);
}
/*
* switch on pgstes for its userspace process (for kvm)
*/
int s390_enable_sie(void)
{
struct task_struct *tsk = current;
struct mm_struct *mm, *old_mm;
struct mm_struct *mm = tsk->mm;
struct mmu_gather tlb;
/* Do we have switched amode? If no, we cannot do sie */
if (s390_user_mode == HOME_SPACE_MODE)
@ -1072,57 +1166,16 @@ int s390_enable_sie(void)
if (mm_has_pgste(tsk->mm))
return 0;
/* lets check if we are allowed to replace the mm */
task_lock(tsk);
if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 ||
#ifdef CONFIG_AIO
!hlist_empty(&tsk->mm->ioctx_list) ||
#endif
tsk->mm != tsk->active_mm) {
task_unlock(tsk);
return -EINVAL;
}
task_unlock(tsk);
/* we copy the mm and let dup_mm create the page tables with_pgstes */
tsk->mm->context.alloc_pgste = 1;
/* make sure that both mms have a correct rss state */
sync_mm_rss(tsk->mm);
mm = dup_mm(tsk);
tsk->mm->context.alloc_pgste = 0;
if (!mm)
return -ENOMEM;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
down_write(&mm->mmap_sem);
/* split thp mappings and disable thp for future mappings */
thp_split_mm(mm);
mm->def_flags |= VM_NOHUGEPAGE;
#endif
/* Now lets check again if something happened */
task_lock(tsk);
if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 ||
#ifdef CONFIG_AIO
!hlist_empty(&tsk->mm->ioctx_list) ||
#endif
tsk->mm != tsk->active_mm) {
mmput(mm);
task_unlock(tsk);
return -EINVAL;
}
/* ok, we are alone. No ptrace, no threads, etc. */
old_mm = tsk->mm;
tsk->mm = tsk->active_mm = mm;
preempt_disable();
update_mm(mm, tsk);
atomic_inc(&mm->context.attach_count);
atomic_dec(&old_mm->context.attach_count);
cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
preempt_enable();
task_unlock(tsk);
mmput(old_mm);
return 0;
/* Reallocate the page tables with pgstes */
mm->context.has_pgste = 1;
tlb_gather_mmu(&tlb, mm, 0);
page_table_realloc(&tlb, mm, 0, TASK_SIZE);
tlb_finish_mmu(&tlb, 0, -1);
up_write(&mm->mmap_sem);
return mm->context.has_pgste ? 0 : -ENOMEM;
}
EXPORT_SYMBOL_GPL(s390_enable_sie);