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authorChristian Borntraeger <borntraeger@de.ibm.com>2014-08-19 16:19:35 +0200
committerChristian Borntraeger <borntraeger@de.ibm.com>2014-08-25 14:35:28 +0200
commitab3f285f227fec62868037e9b1b1fd18294a83b8 (patch)
tree223d790283f4379ce84a87660d100a1f1933cffd /arch/s390/mm/pgtable.c
parent614a80e474b227cace52fd6e3c790554db8a396e (diff)
KVM: s390/mm: try a cow on read only pages for key ops
The PFMF instruction handler blindly wrote the storage key even if the page was mapped R/O in the host. Lets try a COW before continuing and bail out in case of errors. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: stable@vger.kernel.org
Diffstat (limited to 'arch/s390/mm/pgtable.c')
-rw-r--r--arch/s390/mm/pgtable.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 19daa53a3da4..5404a6261db9 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -986,11 +986,21 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
pte_t *ptep;
down_read(&mm->mmap_sem);
+retry:
ptep = get_locked_pte(current->mm, addr, &ptl);
if (unlikely(!ptep)) {
up_read(&mm->mmap_sem);
return -EFAULT;
}
+ if (!(pte_val(*ptep) & _PAGE_INVALID) &&
+ (pte_val(*ptep) & _PAGE_PROTECT)) {
+ pte_unmap_unlock(*ptep, ptl);
+ if (fixup_user_fault(current, mm, addr, FAULT_FLAG_WRITE)) {
+ up_read(&mm->mmap_sem);
+ return -EFAULT;
+ }
+ goto retry;
+ }
new = old = pgste_get_lock(ptep);
pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |