Commit 8ecb1a59 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Christian Borntraeger
Browse files

s390/mm: use RCU for gmap notifier list and the per-mm gmap list 



The gmap notifier list and the gmap list in the mm_struct change rarely.
Use RCU to optimize the reader of these lists.

Reviewed-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 414d3b07

arch/s390/include/asm/gmap.h

+1 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ struct gmap { 
 */

struct gmap_notifier {

	struct list_head list;

	struct rcu_head rcu;

	void (*notifier_call)(struct gmap *gmap, unsigned long start,

			      unsigned long end);

};

arch/s390/include/asm/mmu.h

+7 −4
Original line number Diff line number Diff line
@@ -8,8 +8,9 @@ typedef struct { 
	cpumask_t cpu_attach_mask;

	atomic_t attach_count;

	unsigned int flush_mm;

	spinlock_t list_lock;

	spinlock_t pgtable_lock;

	struct list_head pgtable_list;

	spinlock_t gmap_lock;

	struct list_head gmap_list;

	unsigned long asce;

	unsigned long asce_limit;
@@ -23,8 +24,10 @@ typedef struct { 
} mm_context_t;



#define INIT_MM_CONTEXT(name)						   \

	.context.list_lock    = __SPIN_LOCK_UNLOCKED(name.context.list_lock), \

	.context.pgtable_lock =						   \

			__SPIN_LOCK_UNLOCKED(name.context.pgtable_lock),   \

	.context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \

	.context.gmap_lock = __SPIN_LOCK_UNLOCKED(name.context.gmap_lock), \

	.context.gmap_list = LIST_HEAD_INIT(name.context.gmap_list),



static inline int tprot(unsigned long addr)

arch/s390/include/asm/mmu_context.h

+2 −1
Original line number Diff line number Diff line
@@ -15,8 +15,9 @@ 
static inline int init_new_context(struct task_struct *tsk,

				   struct mm_struct *mm)

{

	spin_lock_init(&mm->context.list_lock);

	spin_lock_init(&mm->context.pgtable_lock);

	INIT_LIST_HEAD(&mm->context.pgtable_list);

	spin_lock_init(&mm->context.gmap_lock);

	INIT_LIST_HEAD(&mm->context.gmap_list);

	cpumask_clear(&mm->context.cpu_attach_mask);

	atomic_set(&mm->context.attach_count, 0);

arch/s390/mm/gmap.c

+23 −16
Original line number Diff line number Diff line
@@ -70,9 +70,9 @@ struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit) 
	gmap->asce = atype | _ASCE_TABLE_LENGTH |

		_ASCE_USER_BITS | __pa(table);

	gmap->asce_end = limit;

	down_write(&mm->mmap_sem);

	list_add(&gmap->list, &mm->context.gmap_list);

	up_write(&mm->mmap_sem);

	spin_lock(&mm->context.gmap_lock);

	list_add_rcu(&gmap->list, &mm->context.gmap_list);

	spin_unlock(&mm->context.gmap_lock);

	return gmap;



out_free:
@@ -128,14 +128,16 @@ void gmap_free(struct gmap *gmap) 
	else

		__tlb_flush_global();



	spin_lock(&gmap->mm->context.gmap_lock);

	list_del_rcu(&gmap->list);

	spin_unlock(&gmap->mm->context.gmap_lock);

	synchronize_rcu();



	/* Free all segment & region tables. */

	list_for_each_entry_safe(page, next, &gmap->crst_list, lru)

		__free_pages(page, 2);

	gmap_radix_tree_free(&gmap->guest_to_host);

	gmap_radix_tree_free(&gmap->host_to_guest);

	down_write(&gmap->mm->mmap_sem);

	list_del(&gmap->list);

	up_write(&gmap->mm->mmap_sem);

	kfree(gmap);

}

EXPORT_SYMBOL_GPL(gmap_free);
@@ -369,11 +371,13 @@ void gmap_unlink(struct mm_struct *mm, unsigned long *table, 
	struct gmap *gmap;

	int flush;



	list_for_each_entry(gmap, &mm->context.gmap_list, list) {

	rcu_read_lock();

	list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {

		flush = __gmap_unlink_by_vmaddr(gmap, vmaddr);

		if (flush)

			gmap_flush_tlb(gmap);

	}

	rcu_read_unlock();

}



/**
@@ -555,7 +559,7 @@ static DEFINE_SPINLOCK(gmap_notifier_lock); 
void gmap_register_ipte_notifier(struct gmap_notifier *nb)

{

	spin_lock(&gmap_notifier_lock);

	list_add(&nb->list, &gmap_notifier_list);

	list_add_rcu(&nb->list, &gmap_notifier_list);

	spin_unlock(&gmap_notifier_lock);

}

EXPORT_SYMBOL_GPL(gmap_register_ipte_notifier);
@@ -567,8 +571,9 @@ EXPORT_SYMBOL_GPL(gmap_register_ipte_notifier); 
void gmap_unregister_ipte_notifier(struct gmap_notifier *nb)

{

	spin_lock(&gmap_notifier_lock);

	list_del_init(&nb->list);

	list_del_rcu(&nb->list);

	spin_unlock(&gmap_notifier_lock);

	synchronize_rcu();

}

EXPORT_SYMBOL_GPL(gmap_unregister_ipte_notifier);
@@ -662,16 +667,18 @@ void ptep_notify(struct mm_struct *mm, unsigned long vmaddr, pte_t *pte) 


	offset = ((unsigned long) pte) & (255 * sizeof(pte_t));

	offset = offset * (4096 / sizeof(pte_t));

	spin_lock(&gmap_notifier_lock);

	list_for_each_entry(gmap, &mm->context.gmap_list, list) {

	rcu_read_lock();

	list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {

		spin_lock(&gmap->guest_table_lock);

		table = radix_tree_lookup(&gmap->host_to_guest,

					  vmaddr >> PMD_SHIFT);

		if (!table)

			continue;

		if (table)

			gaddr = __gmap_segment_gaddr(table) + offset;

		spin_unlock(&gmap->guest_table_lock);

		if (table)

			gmap_call_notifier(gmap, gaddr, gaddr + PAGE_SIZE - 1);

	}

	spin_unlock(&gmap_notifier_lock);

	rcu_read_unlock();

}

EXPORT_SYMBOL_GPL(ptep_notify);

arch/s390/mm/pgalloc.c

+8 −8
Original line number Diff line number Diff line
@@ -149,7 +149,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm) 
	/* Try to get a fragment of a 4K page as a 2K page table */

	if (!mm_alloc_pgste(mm)) {

		table = NULL;

		spin_lock_bh(&mm->context.list_lock);

		spin_lock_bh(&mm->context.pgtable_lock);

		if (!list_empty(&mm->context.pgtable_list)) {

			page = list_first_entry(&mm->context.pgtable_list,

						struct page, lru);
@@ -164,7 +164,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm) 
				list_del(&page->lru);

			}

		}

		spin_unlock_bh(&mm->context.list_lock);

		spin_unlock_bh(&mm->context.pgtable_lock);

		if (table)

			return table;

	}
@@ -187,9 +187,9 @@ unsigned long *page_table_alloc(struct mm_struct *mm) 
		/* Return the first 2K fragment of the page */

		atomic_set(&page->_mapcount, 1);

		clear_table(table, _PAGE_INVALID, PAGE_SIZE);

		spin_lock_bh(&mm->context.list_lock);

		spin_lock_bh(&mm->context.pgtable_lock);

		list_add(&page->lru, &mm->context.pgtable_list);

		spin_unlock_bh(&mm->context.list_lock);

		spin_unlock_bh(&mm->context.pgtable_lock);

	}

	return table;

}
@@ -203,13 +203,13 @@ void page_table_free(struct mm_struct *mm, unsigned long *table) 
	if (!mm_alloc_pgste(mm)) {

		/* Free 2K page table fragment of a 4K page */

		bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));

		spin_lock_bh(&mm->context.list_lock);

		spin_lock_bh(&mm->context.pgtable_lock);

		mask = atomic_xor_bits(&page->_mapcount, 1U << bit);

		if (mask & 3)

			list_add(&page->lru, &mm->context.pgtable_list);

		else

			list_del(&page->lru);

		spin_unlock_bh(&mm->context.list_lock);

		spin_unlock_bh(&mm->context.pgtable_lock);

		if (mask != 0)

			return;

	}
@@ -235,13 +235,13 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, 
		return;

	}

	bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));

	spin_lock_bh(&mm->context.list_lock);

	spin_lock_bh(&mm->context.pgtable_lock);

	mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit);

	if (mask & 3)

		list_add_tail(&page->lru, &mm->context.pgtable_list);

	else

		list_del(&page->lru);

	spin_unlock_bh(&mm->context.list_lock);

	spin_unlock_bh(&mm->context.pgtable_lock);

	table = (unsigned long *) (__pa(table) | (1U << bit));

	tlb_remove_table(tlb, table);

}

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