spapr: Do NVDIMM/PC-DIMM device hotplug sanity checks at pre-plug only

Pre-plug of a memory device, be it an NVDIMM or a PC-DIMM, ensures
that the memory slot is available and that addresses don't overlap
with existing memory regions. The corresponding DRCs in the LMB
and PMEM namespaces are thus necessarily attachable at plug time.

Pass &error_abort to spapr_drc_attach() in spapr_add_lmbs() and
spapr_add_nvdimm(). This allows to greatly simplify error handling
on the plug path.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20201120234208.683521-3-groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

2 files changed, 19 insertions, 32 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 6abb45d..9489c57 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -3379,8 +3379,8 @@ int spapr_lmb_dt_populate(SpaprDrc *drc, SpaprMachineState *spapr,
     return 0;
 }
 
-static bool spapr_add_lmbs(DeviceState *dev, uint64_t addr_start, uint64_t size,
-                           bool dedicated_hp_event_source, Error **errp)
+static void spapr_add_lmbs(DeviceState *dev, uint64_t addr_start, uint64_t size,
+                           bool dedicated_hp_event_source)
 {
     SpaprDrc *drc;
     uint32_t nr_lmbs = size/SPAPR_MEMORY_BLOCK_SIZE;
@@ -3393,15 +3393,12 @@ static bool spapr_add_lmbs(DeviceState *dev, uint64_t addr_start, uint64_t size,
                               addr / SPAPR_MEMORY_BLOCK_SIZE);
         g_assert(drc);
 
-        if (!spapr_drc_attach(drc, dev, errp)) {
-            while (addr > addr_start) {
-                addr -= SPAPR_MEMORY_BLOCK_SIZE;
-                drc = spapr_drc_by_id(TYPE_SPAPR_DRC_LMB,
-                                      addr / SPAPR_MEMORY_BLOCK_SIZE);
-                spapr_drc_detach(drc);
-            }
-            return false;
-        }
+        /*
+         * memory_device_get_free_addr() provided a range of free addresses
+         * that doesn't overlap with any existing mapping at pre-plug. The
+         * corresponding LMB DRCs are thus assumed to be all attachable.
+         */
+        spapr_drc_attach(drc, dev, &error_abort);
         if (!hotplugged) {
             spapr_drc_reset(drc);
         }
@@ -3422,11 +3419,9 @@ static bool spapr_add_lmbs(DeviceState *dev, uint64_t addr_start, uint64_t size,
                                            nr_lmbs);
         }
     }
-    return true;
 }
 
-static void spapr_memory_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
-                              Error **errp)
+static void spapr_memory_plug(HotplugHandler *hotplug_dev, DeviceState *dev)
 {
     SpaprMachineState *ms = SPAPR_MACHINE(hotplug_dev);
     PCDIMMDevice *dimm = PC_DIMM(dev);
@@ -3441,24 +3436,15 @@ static void spapr_memory_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     if (!is_nvdimm) {
         addr = object_property_get_uint(OBJECT(dimm),
                                         PC_DIMM_ADDR_PROP, &error_abort);
-        if (!spapr_add_lmbs(dev, addr, size,
-                            spapr_ovec_test(ms->ov5_cas, OV5_HP_EVT), errp)) {
-            goto out_unplug;
-        }
+        spapr_add_lmbs(dev, addr, size,
+                       spapr_ovec_test(ms->ov5_cas, OV5_HP_EVT));
     } else {
         slot = object_property_get_int(OBJECT(dimm),
                                        PC_DIMM_SLOT_PROP, &error_abort);
         /* We should have valid slot number at this point */
         g_assert(slot >= 0);
-        if (!spapr_add_nvdimm(dev, slot, errp)) {
-            goto out_unplug;
-        }
+        spapr_add_nvdimm(dev, slot);
     }
-
-    return;
-
-out_unplug:
-    pc_dimm_unplug(dimm, MACHINE(ms));
 }
 
 static void spapr_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
@@ -4006,7 +3992,7 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
                                       DeviceState *dev, Error **errp)
 {
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
-        spapr_memory_plug(hotplug_dev, dev, errp);
+        spapr_memory_plug(hotplug_dev, dev);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
         spapr_core_plug(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_PCI_HOST_BRIDGE)) {
diff --git a/hw/ppc/spapr_nvdimm.c b/hw/ppc/spapr_nvdimm.c
index a833a63..2f1c196 100644
--- a/hw/ppc/spapr_nvdimm.c
+++ b/hw/ppc/spapr_nvdimm.c
@@ -89,7 +89,7 @@ bool spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
 }
 
 
-bool spapr_add_nvdimm(DeviceState *dev, uint64_t slot, Error **errp)
+void spapr_add_nvdimm(DeviceState *dev, uint64_t slot)
 {
     SpaprDrc *drc;
     bool hotplugged = spapr_drc_hotplugged(dev);
@@ -97,14 +97,15 @@ bool spapr_add_nvdimm(DeviceState *dev, uint64_t slot, Error **errp)
     drc = spapr_drc_by_id(TYPE_SPAPR_DRC_PMEM, slot);
     g_assert(drc);
 
-    if (!spapr_drc_attach(drc, dev, errp)) {
-        return false;
-    }
+    /*
+     * pc_dimm_get_free_slot() provided a free slot at pre-plug. The
+     * corresponding DRC is thus assumed to be attachable.
+     */
+    spapr_drc_attach(drc, dev, &error_abort);
 
     if (hotplugged) {
         spapr_hotplug_req_add_by_index(drc);
     }
-    return true;
 }
 
 static int spapr_dt_nvdimm(SpaprMachineState *spapr, void *fdt,