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Commit 934bc131 authored by Dominik Dingel's avatar Dominik Dingel Committed by Christian Borntraeger
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KVM: s390: Allow skeys to be enabled for the current process 



Introduce a new function s390_enable_skey(), which enables storage key
handling via setting the use_skey flag in the mmu context.

This function is only useful within the context of kvm.

Note that enabling storage keys will cause a one-time hickup when
walking the page table; however, it saves us special effort for cases
like clear reset while making it possible for us to be architecture
conform.

s390_enable_skey() takes the page table lock to prevent reseting
storage keys triggered from multiple vcpus.

Signed-off-by: default avatarDominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent d4cb1134

arch/s390/include/asm/pgtable.h

+1 −0
Original line number Diff line number Diff line
@@ -1747,6 +1747,7 @@ static inline pte_t mk_swap_pte(unsigned long type, unsigned long offset) 
extern int vmem_add_mapping(unsigned long start, unsigned long size);

extern int vmem_remove_mapping(unsigned long start, unsigned long size);

extern int s390_enable_sie(void);

extern void s390_enable_skey(void);



/*

 * No page table caches to initialise

arch/s390/mm/pgtable.c

+23 −0
Original line number Diff line number Diff line
@@ -1378,6 +1378,29 @@ int s390_enable_sie(void) 
}

EXPORT_SYMBOL_GPL(s390_enable_sie);



/*

 * Enable storage key handling from now on and initialize the storage

 * keys with the default key.

 */

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);



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

int pmdp_clear_flush_young(struct vm_area_struct *vma, unsigned long address,

			   pmd_t *pmdp)