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s390/kvm: 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: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Christian Borntraeger 2013-05-27 10:42:04 +02:00 committed by Martin Schwidefsky
parent 25b41a7b67
commit 24d5dd0208
2 changed files with 51 additions and 0 deletions
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3
arch/s390/include/asm/pgalloc.h
View File

@ -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;

48
arch/s390/mm/pgtable.c
View File

@ -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,