[Qemu-devel] [PULL 17/18] hw/ppc/spapr.c: recover pending LMB unplug info in spapr_lmb_release

[David Gibson <david@gibson.dropbear.id.au>]

From: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>

When a LMB hot unplug starts, the current DRC LMB status is stored at
spapr->pending_dimm_unplugs QTAILQ. This queue isn't migrated, thus
if a migration occurs in the middle of a LMB unplug the
spapr_lmb_release callback will lost track of the LMB unplug progress.

This patch implements a new recover function spapr_recover_pending_dimm_state
that is used inside spapr_lmb_release to recover this DRC LMB release
status that is lost during the migration.

Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
[dwg: Minor stylistic changes, simplify error handling]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 14399f4..ab3aab1 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2655,6 +2655,40 @@ static void spapr_pending_dimm_unplugs_remove(sPAPRMachineState *spapr,
     g_free(dimm_state);
 }
 
+static sPAPRDIMMState *spapr_recover_pending_dimm_state(sPAPRMachineState *ms,
+                                                        PCDIMMDevice *dimm)
+{
+    sPAPRDRConnector *drc;
+    PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
+    MemoryRegion *mr = ddc->get_memory_region(dimm);
+    uint64_t size = memory_region_size(mr);
+    uint32_t nr_lmbs = size / SPAPR_MEMORY_BLOCK_SIZE;
+    uint32_t avail_lmbs = 0;
+    uint64_t addr_start, addr;
+    int i;
+    sPAPRDIMMState *ds;
+
+    addr_start = object_property_get_int(OBJECT(dimm), PC_DIMM_ADDR_PROP,
+                                         &error_abort);
+
+    addr = addr_start;
+    for (i = 0; i < nr_lmbs; i++) {
+        drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
+                                       addr / SPAPR_MEMORY_BLOCK_SIZE);
+        g_assert(drc);
+        if (drc->indicator_state != SPAPR_DR_INDICATOR_STATE_INACTIVE) {
+            avail_lmbs++;
+        }
+        addr += SPAPR_MEMORY_BLOCK_SIZE;
+    }
+
+    ds = g_malloc0(sizeof(sPAPRDIMMState));
+    ds->nr_lmbs = avail_lmbs;
+    ds->dimm = dimm;
+    spapr_pending_dimm_unplugs_add(ms, ds);
+    return ds;
+}
+
 /* Callback to be called during DRC release. */
 void spapr_lmb_release(DeviceState *dev)
 {
@@ -2662,7 +2696,14 @@ void spapr_lmb_release(DeviceState *dev)
     sPAPRMachineState *spapr = SPAPR_MACHINE(hotplug_ctrl);
     sPAPRDIMMState *ds = spapr_pending_dimm_unplugs_find(spapr, PC_DIMM(dev));
 
-    if (--ds->nr_lmbs) {
+    /* This information will get lost if a migration occurs
+     * during the unplug process. In this case recover it. */
+    if (ds == NULL) {
+        ds = spapr_recover_pending_dimm_state(spapr, PC_DIMM(dev));
+        if (ds->nr_lmbs) {
+            return;
+        }
+    } else if (--ds->nr_lmbs) {
         return;
     }
 
-- 
2.9.4