From ab3f285f227fec62868037e9b1b1fd18294a83b8 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Tue, 19 Aug 2014 16:19:35 +0200 Subject: [PATCH] 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 Reviewed-by: Dominik Dingel Cc: stable@vger.kernel.org --- arch/s390/mm/pgtable.c | 10 ++++++++++ 1 file changed, 10 insertions(+) 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 |