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Commit ab3f285f authored by Christian Borntraeger's avatar Christian Borntraeger
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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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarDominik Dingel <dingel@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
parent 614a80e4

arch/s390/mm/pgtable.c

+10 −0
Original line number Diff line number Diff line
@@ -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 |