spapr_pci: Reset DMA config on PHB reset

LoPAPR dictates that during system reset all DMA windows must be removed
and the default DMA32 window must be created so does the patch.

At the moment there is just one window supported so no change in
behaviour is expected.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr_pci.c

@@ -1310,7 +1310,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
     PCIBus *bus;
     uint64_t msi_window_size = 4096;
     sPAPRTCETable *tcet;
-    uint32_t nb_table;
 
     if (sphb->index != (uint32_t)-1) {
         hwaddr windows_base;
@@ -1462,7 +1461,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
         }
     }
 
-    nb_table = sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT;
     tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn);
     if (!tcet) {
         error_setg(errp, "Unable to create TCE table for %s",
@@ -1473,10 +1471,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
     memory_region_add_subregion_overlap(&sphb->iommu_root, 0,
                                         spapr_tce_get_iommu(tcet), 0);
 
-    /* Register default 32bit DMA window */
-    spapr_tce_table_enable(tcet, SPAPR_TCE_PAGE_SHIFT, sphb->dma_win_addr,
-                           nb_table);
-
     sphb->msi = g_hash_table_new_full(g_int_hash, g_int_equal, g_free, g_free);
 }
 
@@ -1493,6 +1487,17 @@ static int spapr_phb_children_reset(Object *child, void *opaque)
 
 static void spapr_phb_reset(DeviceState *qdev)
 {
+    sPAPRPHBState *sphb = SPAPR_PCI_HOST_BRIDGE(qdev);
+    sPAPRTCETable *tcet = spapr_tce_find_by_liobn(sphb->dma_liobn);
+
+    if (tcet && tcet->nb_table) {
+        spapr_tce_table_disable(tcet);
+    }
+
+    /* Register default 32bit DMA window */
+    spapr_tce_table_enable(tcet, SPAPR_TCE_PAGE_SHIFT, sphb->dma_win_addr,
+                           sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT);
+
     /* Reset the IOMMU state */
     object_child_foreach(OBJECT(qdev), spapr_phb_children_reset, NULL);