KVM: x86: add tracepoints around __direct_map and FNAME(fetch)

commit 335e192a3fa415e1202c8b9ecdaaecd643f823cc upstream.

These are useful in debugging shadow paging.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 4.9:
 - Keep using PT_PRESENT_MASK to test page write permission
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>