From ad7aaf34400b1bbd41bbec182fd5895eaad50932 Mon Sep 17 00:00:00 2001
From: Greg Kurz <gkurz@redhat.com>
Date: Tue, 19 Jan 2021 15:09:51 -0500
Subject: [PATCH 3/9] spapr: Don't use spapr_drc_needed() in CAS code

RH-Author: Greg Kurz <gkurz@redhat.com>
Message-id: <20210119150954.1017058-4-gkurz@redhat.com>
Patchwork-id: 100683
O-Subject: [RHEL-8.4.0 qemu-kvm PATCH v2 3/6] spapr: Don't use spapr_drc_needed() in CAS code
Bugzilla: 1901837
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
RH-Acked-by: David Gibson <dgibson@redhat.com>

From: Greg Kurz <groug@kaod.org>

We currently don't support hotplug of devices between boot and CAS. If
this happens a CAS reboot is triggered. We detect this during CAS using
the spapr_drc_needed() function which is essentially a VMStateDescription
.needed callback. Even if the condition for CAS reboot happens to be the
same as for DRC migration, it looks wrong to piggyback a migration helper
for this.

Introduce a helper with slightly more explicit name and use it in both CAS
and DRC migration code. Since a subsequent patch will enhance this helper
to cover the case of hot unplug, let's go for spapr_drc_transient(). While
here convert spapr_hotplugged_dev_before_cas() to the "transient" wording as
well.

This doesn't change any behaviour.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <158169248180.3465937.9531405453362718771.stgit@bahia.lan>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
(cherry picked from commit 4b63db1289a9e597bc151fa5e4d72f882cb6de1e)
Signed-off-by: Greg Kurz <gkurz@redhat.com>
Signed-off-by: Jon Maloy <jmaloy.redhat.com>
---
 hw/ppc/spapr_drc.c         | 20 ++++++++++++++------
 hw/ppc/spapr_hcall.c       | 14 +++++++++-----
 include/hw/ppc/spapr_drc.h |  4 +++-
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 62f1a42592..9b498d429e 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -455,23 +455,31 @@ void spapr_drc_reset(SpaprDrc *drc)
     }
 }
 
-bool spapr_drc_needed(void *opaque)
+bool spapr_drc_transient(SpaprDrc *drc)
 {
-    SpaprDrc *drc = (SpaprDrc *)opaque;
     SpaprDrcClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
 
-    /* If no dev is plugged in there is no need to migrate the DRC state */
+    /*
+     * If no dev is plugged in there is no need to migrate the DRC state
+     * nor to reset the DRC at CAS.
+     */
     if (!drc->dev) {
         return false;
     }
 
     /*
-     * We need to migrate the state if it's not equal to the expected
-     * long-term state, which is the same as the coldplugged initial
-     * state */
+     * We need to reset the DRC at CAS or to migrate the DRC state if it's
+     * not equal to the expected long-term state, which is the same as the
+     * coldplugged initial state.
+     */
     return (drc->state != drck->ready_state);
 }
 
+static bool spapr_drc_needed(void *opaque)
+{
+    return spapr_drc_transient(opaque);
+}
+
 static const VMStateDescription vmstate_spapr_drc = {
     .name = "spapr_drc",
     .version_id = 1,
diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 0f19be794c..d70e643752 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1640,20 +1640,24 @@ static uint32_t cas_check_pvr(SpaprMachineState *spapr, PowerPCCPU *cpu,
     return best_compat;
 }
 
-static bool spapr_hotplugged_dev_before_cas(void)
+static bool spapr_transient_dev_before_cas(void)
 {
-    Object *drc_container, *obj;
+    Object *drc_container;
     ObjectProperty *prop;
     ObjectPropertyIterator iter;
 
     drc_container = container_get(object_get_root(), "/dr-connector");
     object_property_iter_init(&iter, drc_container);
     while ((prop = object_property_iter_next(&iter))) {
+        SpaprDrc *drc;
+
         if (!strstart(prop->type, "link<", NULL)) {
             continue;
         }
-        obj = object_property_get_link(drc_container, prop->name, NULL);
-        if (spapr_drc_needed(obj)) {
+        drc = SPAPR_DR_CONNECTOR(object_property_get_link(drc_container,
+                                                          prop->name, NULL));
+
+        if (spapr_drc_transient(drc)) {
             return true;
         }
     }
@@ -1812,7 +1816,7 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
 
     spapr_irq_update_active_intc(spapr);
 
-    if (spapr_hotplugged_dev_before_cas()) {
+    if (spapr_transient_dev_before_cas()) {
         spapr->cas_reboot = true;
     }
 
diff --git a/include/hw/ppc/spapr_drc.h b/include/hw/ppc/spapr_drc.h
index 83f03cc577..7e09d57114 100644
--- a/include/hw/ppc/spapr_drc.h
+++ b/include/hw/ppc/spapr_drc.h
@@ -269,7 +269,9 @@ int spapr_dt_drc(void *fdt, int offset, Object *owner, uint32_t drc_type_mask);
 
 void spapr_drc_attach(SpaprDrc *drc, DeviceState *d, Error **errp);
 void spapr_drc_detach(SpaprDrc *drc);
-bool spapr_drc_needed(void *opaque);
+
+/* Returns true if a hot plug/unplug request is pending */
+bool spapr_drc_transient(SpaprDrc *drc);
 
 static inline bool spapr_drc_unplug_requested(SpaprDrc *drc)
 {
-- 
2.18.2

