commit 2b29a9fd upstream.

Any uaccess between guest_enter and guest_exit could trigger a page fault,
the page fault handler would handle it as a guest fault and translate a
user address as guest address.
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 3.2: adjust context and add the rc variable]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>