Spapr capabilities are checked at machine init. If a capability cannot
be used, an error message is printed and QEMU exits. In most places,
the error message also contains an hint for the user. But we should
use error_append_hint() for that, as explained in the "qapi/error.h"
header.

This is already the case for cap_fwnmi_apply() and we now want to add 
a similar check for nested KVM-HV. Unfortunately, spapr_caps_apply()
passes &error_fatal to all apply hooks and error_append_hint() is
never called. 

So this reuses previous work from Vladimir Sementsov-Ogievskiy to
address that.

v2: - Fix indentation and add some missing \n in patch 2
    - Add ERRP_AUTO_PROPAGATE() to cap_nested_kvm_hv_apply() in
      patch 2 instead of patch 3
---

Greg Kurz (2):
      spapr: Use error_append_hint() in spapr_caps.c
      spapr: Forbid nested KVM-HV in pre-power9 compat mode

Vladimir Sementsov-Ogievskiy (1):
      error: auto propagated local_err


 hw/ppc/spapr_caps.c  |  105 ++++++++++++++++----------
 include/qapi/error.h |  205 ++++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 237 insertions(+), 73 deletions(-)

--
Greg