KVM: s390: correct locking for s390_enable_skey (3a801517) · Commits · 戴 / test

arch/s390/mm/pgtable.c

+7 −15

Original line number	Diff line number	Diff line
		@@ -958,8 +958,10 @@ void page_table_reset_pgste(struct mm_struct *mm, unsigned long start,
		unsigned long addr, next;
		pgd_t *pgd;

		down_write(&mm->mmap_sem);
		if (init_skey && mm_use_skey(mm))
		goto out_up;
		addr = start;
		down_read(&mm->mmap_sem);
		pgd = pgd_offset(mm, addr);
		do {
		next = pgd_addr_end(addr, end);
		@@ -967,7 +969,10 @@ void page_table_reset_pgste(struct mm_struct *mm, unsigned long start,
		continue;
		next = page_table_reset_pud(mm, pgd, addr, next, init_skey);
		} while (pgd++, addr = next, addr != end);
		up_read(&mm->mmap_sem);
		if (init_skey)
		current->mm->context.use_skey = 1;
		out_up:
		up_write(&mm->mmap_sem);
		}
		EXPORT_SYMBOL(page_table_reset_pgste);

		@@ -1384,19 +1389,6 @@ EXPORT_SYMBOL_GPL(s390_enable_sie);
		*/
		void s390_enable_skey(void)
		{
		/*
		* To avoid races between multiple vcpus, ending in calling
		* page_table_reset twice or more,
		* the page_table_lock is taken for serialization.
		*/
		spin_lock(&current->mm->page_table_lock);
		if (mm_use_skey(current->mm)) {
		spin_unlock(&current->mm->page_table_lock);
		return;
		}

		current->mm->context.use_skey = 1;
		spin_unlock(&current->mm->page_table_lock);
		page_table_reset_pgste(current->mm, 0, TASK_SIZE, true);
		}
		EXPORT_SYMBOL_GPL(s390_enable_skey);