[Qemu-devel] [QEMU RFC PATCH v2 1/6] spapr: ensure device trees are always associated with DRC

[Jianjun Duan]

There are possible racing situations involving hotplug events and
guest migration. For cases where a hotplug event is migrated, or
the guest is in the process of fetching device tree at the time of
migration, we need to ensure the device tree is created and
associated with the corresponding DRC for devices that were
hotplugged on the source, but 'coldplugged' on the target.

Signed-off-by: Jianjun Duan <du...@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c     | 16 ++++++----------
 hw/ppc/spapr_pci.c | 12 +++++-------
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index b69995e..ec18bee 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2131,15 +2131,6 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t 
addr, uint64_t size,
     int i, fdt_offset, fdt_size;
     void *fdt;
 
-    /*
-     * Check for DRC connectors and send hotplug notification to the
-     * guest only in case of hotplugged memory. This allows cold plugged
-     * memory to be specified at boot time.
-     */
-    if (!dev->hotplugged) {
-        return;
-    }
-
     for (i = 0; i < nr_lmbs; i++) {
         drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
                 addr/SPAPR_MEMORY_BLOCK_SIZE);
@@ -2153,7 +2144,12 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t 
addr, uint64_t size,
         drck->attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, errp);
         addr += SPAPR_MEMORY_BLOCK_SIZE;
     }
-    spapr_hotplug_req_add_by_count(SPAPR_DR_CONNECTOR_TYPE_LMB, nr_lmbs);
+    /* send hotplug notification to the
+     * guest only in case of hotplugged memory
+     */
+    if (dev->hotplugged) {
+       spapr_hotplug_req_add_by_count(SPAPR_DR_CONNECTOR_TYPE_LMB, nr_lmbs);
+    }
 }
 
 static void spapr_memory_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 573e635..f0b9de9 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1092,13 +1092,11 @@ static void spapr_phb_add_pci_device(sPAPRDRConnector 
*drc,
         spapr_tce_set_need_vfio(tcet, true);
     }
 
-    if (dev->hotplugged) {
-        fdt = create_device_tree(&fdt_size);
-        fdt_start_offset = spapr_create_pci_child_dt(phb, pdev, fdt, 0);
-        if (!fdt_start_offset) {
-            error_setg(errp, "Failed to create pci child device tree node");
-            goto out;
-        }
+    fdt = create_device_tree(&fdt_size);
+    fdt_start_offset = spapr_create_pci_child_dt(phb, pdev, fdt, 0);
+    if (!fdt_start_offset) {
+        error_setg(errp, "Failed to create pci child device tree node");
+        goto out;
     }
 
     drck->attach(drc, DEVICE(pdev),
-- 
1.9.1