spapr: fix migration to pseries machine < 2.8

since commit 5c4537bd ("spapr: Fix 2.7<->2.8 migration of PCI host bridge"),
some migration fields are forged from the new ones in spapr_pci_pre_save().

It works well, except when the number of MSI devices is 0,
because in this case the function exits immediately.

This fix moves the migration code before the exit code.

The problem can be reproduced with these commands:

source qemu-2.9:

    qemu-system-ppc64 -monitor stdio -M pseries-2.6 -nodefaults -S

destination qemu-2.6:

    qemu-system-ppc64 -monitor stdio -M pseries-2.6 -nodefaults \
                      -incoming tcp:0:4444

on the source:

    migrate tcp:localhost:4444

Destination fails with the following error:

    qemu-system-ppc64: error while loading state for
                       instance 0x0 of device 'spapr_pci'
    qemu-system-ppc64: load of migration failed: Invalid argument

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
(cherry picked from commit e806b4db1477a1c6bfda7bba28c7f26c47f18e1e)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

1 files changed, 14 insertions, 14 deletions

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 98c52e411f..ecfbf0138e 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1893,20 +1893,6 @@ static void spapr_pci_pre_save(void *opaque)
     gpointer key, value;
     int i;
 
-    g_free(sphb->msi_devs);
-    sphb->msi_devs = NULL;
-    sphb->msi_devs_num = g_hash_table_size(sphb->msi);
-    if (!sphb->msi_devs_num) {
-        return;
-    }
-    sphb->msi_devs = g_malloc(sphb->msi_devs_num * sizeof(spapr_pci_msi_mig));
-
-    g_hash_table_iter_init(&iter, sphb->msi);
-    for (i = 0; g_hash_table_iter_next(&iter, &key, &value); ++i) {
-        sphb->msi_devs[i].key = *(uint32_t *) key;
-        sphb->msi_devs[i].value = *(spapr_pci_msi *) value;
-    }
-
     if (sphb->pre_2_8_migration) {
         sphb->mig_liobn = sphb->dma_liobn[0];
         sphb->mig_mem_win_addr = sphb->mem_win_addr;
@@ -1920,6 +1906,20 @@ static void spapr_pci_pre_save(void *opaque)
             sphb->mig_mem_win_size += sphb->mem64_win_size;
         }
     }
+
+    g_free(sphb->msi_devs);
+    sphb->msi_devs = NULL;
+    sphb->msi_devs_num = g_hash_table_size(sphb->msi);
+    if (!sphb->msi_devs_num) {
+        return;
+    }
+    sphb->msi_devs = g_malloc(sphb->msi_devs_num * sizeof(spapr_pci_msi_mig));
+
+    g_hash_table_iter_init(&iter, sphb->msi);
+    for (i = 0; g_hash_table_iter_next(&iter, &key, &value); ++i) {
+        sphb->msi_devs[i].key = *(uint32_t *) key;
+        sphb->msi_devs[i].value = *(spapr_pci_msi *) value;
+    }
 }
 
 static int spapr_pci_post_load(void *opaque, int version_id)