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Commit db70ccdf authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Paolo Bonzini
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KVM: s390: Provide function for setting the guest storage key 



From time to time we need to set the guest storage key. Lets
provide a helper function that handles the changes with all the
right locking and checking.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8915aa27

arch/s390/include/asm/pgalloc.h

+3 −0
Original line number Diff line number Diff line
@@ -22,6 +22,9 @@ unsigned long *page_table_alloc(struct mm_struct *, unsigned long); 
void page_table_free(struct mm_struct *, unsigned long *);

void page_table_free_rcu(struct mmu_gather *, unsigned long *);



int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,

			  unsigned long key, bool nq);



static inline void clear_table(unsigned long *s, unsigned long val, size_t n)

{

	typedef struct { char _[n]; } addrtype;

arch/s390/mm/pgtable.c

+48 −0
Original line number Diff line number Diff line
@@ -771,6 +771,54 @@ static inline void page_table_free_pgste(unsigned long *table) 
	__free_page(page);

}



int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,

			  unsigned long key, bool nq)

{

	spinlock_t *ptl;

	pgste_t old, new;

	pte_t *ptep;



	down_read(&mm->mmap_sem);

	ptep = get_locked_pte(current->mm, addr, &ptl);

	if (unlikely(!ptep)) {

		up_read(&mm->mmap_sem);

		return -EFAULT;

	}



	new = old = pgste_get_lock(ptep);

	pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |

			    PGSTE_ACC_BITS | PGSTE_FP_BIT);

	pgste_val(new) |= (key & (_PAGE_CHANGED | _PAGE_REFERENCED)) << 48;

	pgste_val(new) |= (key & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;

	if (!(pte_val(*ptep) & _PAGE_INVALID)) {

		unsigned long address, bits;

		unsigned char skey;



		address = pte_val(*ptep) & PAGE_MASK;

		skey = page_get_storage_key(address);

		bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);

		/* Set storage key ACC and FP */

		page_set_storage_key(address,

				(key & (_PAGE_ACC_BITS | _PAGE_FP_BIT)),

				!nq);



		/* Merge host changed & referenced into pgste  */

		pgste_val(new) |= bits << 52;

		/* Transfer skey changed & referenced bit to kvm user bits */

		pgste_val(new) |= bits << 45;	/* PGSTE_UR_BIT & PGSTE_UC_BIT */

	}

	/* changing the guest storage key is considered a change of the page */

	if ((pgste_val(new) ^ pgste_val(old)) &

	    (PGSTE_ACC_BITS | PGSTE_FP_BIT | PGSTE_GR_BIT | PGSTE_GC_BIT))

		pgste_val(new) |= PGSTE_UC_BIT;



	pgste_set_unlock(ptep, new);

	pte_unmap_unlock(*ptep, ptl);

	up_read(&mm->mmap_sem);

	return 0;

}

EXPORT_SYMBOL(set_guest_storage_key);



#else /* CONFIG_PGSTE */



static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,