KVM: s390/mm: try a cow on read only pages for key ops (ab3f285f) · Commits · 戴 / test

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

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 \|

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