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Commit 3eabaee9 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Paolo Bonzini
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 663f4c61

arch/s390/include/asm/mmu.h

+0 −2
Original line number Diff line number Diff line
@@ -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;

arch/s390/include/asm/mmu_context.h

+1 −18
Original line number Diff line number Diff line
@@ -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.asce_limit = STACK_TOP_MAX;

	crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));

	return 0;

arch/s390/include/asm/pgtable.h

+11 −0
Original line number Diff line number Diff line
@@ -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

arch/s390/mm/pgtable.c

+117 −64
Original line number Diff line number Diff line
@@ -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);