spapr: fix CAS-generated reset

The OV5_MMU_RADIX_300 requires special handling in the CAS negotiation
process. It is cleared from the option vector of the guest before
evaluating the changes and re-added later. But, when testing for a
possible CAS reset :

    spapr->cas_reboot = spapr_ovec_diff(ov5_updates,
                                        ov5_cas_old, spapr->ov5_cas);

the bit OV5_MMU_RADIX_300 will each time be seen as removed from the
previous OV5 set, hence generating a reset loop.

Fix this problem by also clearing the same bit in the ov5_cas_old set.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 7 insertions, 0 deletions

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 6ab8c188f3..57bb411394 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1581,6 +1581,13 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
      * to worry about this for now.
      */
     ov5_cas_old = spapr_ovec_clone(spapr->ov5_cas);
+
+    /* also clear the radix/hash bit from the current ov5_cas bits to
+     * be in sync with the newly ov5 bits. Else the radix bit will be
+     * seen as being removed and this will generate a reset loop
+     */
+    spapr_ovec_clear(ov5_cas_old, OV5_MMU_RADIX_300);
+
     /* full range of negotiated ov5 capabilities */
     spapr_ovec_intersect(spapr->ov5_cas, spapr->ov5, ov5_guest);
     spapr_ovec_cleanup(ov5_guest);