From 150f462538a6f3b78efe785c911669375032b0d2 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 30 Jan 2019 16:57:29 +0100 Subject: [PATCH] s390x/pci: Fix hotplugging of PCI bridges When hotplugging a PCI bridge right now to the root port, we resolve pci_get_bus(pdev)->parent_dev, which results in a SEGFAULT. Hotplugging really only works right now when hotplugging to another bridge. Instead, we have to properly check if we are already at the root. Let's cleanup the code while at it a bit and factor out updating the subordinate bus number into a separate function. The check for "old_nr < nr" is right now not strictly necessary, but makes it more obvious what is actually going on. Most probably fixing up the topology is not our responsibility when hotplugging. The guest has to sort this out. But let's keep it for now and only fix current code to not crash. Reviewed-by: Thomas Huth Signed-off-by: David Hildenbrand Message-Id: <20190130155733.32742-3-david@redhat.com> Reviewed-by: Collin Walling Signed-off-by: Cornelia Huck --- hw/s390x/s390-pci-bus.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-) diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c index 4200e48fb9..d85bc34617 100644 --- a/hw/s390x/s390-pci-bus.c +++ b/hw/s390x/s390-pci-bus.c @@ -877,6 +877,21 @@ static void s390_pcihost_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev, } } +static void s390_pci_update_subordinate(PCIDevice *dev, uint32_t nr) +{ + uint32_t old_nr; + + pci_default_write_config(dev, PCI_SUBORDINATE_BUS, nr, 1); + while (!pci_bus_is_root(pci_get_bus(dev))) { + dev = pci_get_bus(dev)->parent_dev; + + old_nr = pci_default_read_config(dev, PCI_SUBORDINATE_BUS, 1); + if (old_nr < nr) { + pci_default_write_config(dev, PCI_SUBORDINATE_BUS, nr, 1); + } + } +} + static void s390_pcihost_plug(HotplugHandler *hotplug_dev, DeviceState *dev, Error **errp) { @@ -885,26 +900,21 @@ static void s390_pcihost_plug(HotplugHandler *hotplug_dev, DeviceState *dev, S390PCIBusDevice *pbdev = NULL; if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) { - BusState *bus; PCIBridge *pb = PCI_BRIDGE(dev); - PCIDevice *pdev = PCI_DEVICE(dev); + pdev = PCI_DEVICE(dev); pci_bridge_map_irq(pb, dev->id, s390_pci_map_irq); pci_setup_iommu(&pb->sec_bus, s390_pci_dma_iommu, s); - bus = BUS(&pb->sec_bus); - qbus_set_hotplug_handler(bus, DEVICE(s), errp); + qbus_set_hotplug_handler(BUS(&pb->sec_bus), DEVICE(s), errp); if (dev->hotplugged) { pci_default_write_config(pdev, PCI_PRIMARY_BUS, pci_dev_bus_num(pdev), 1); s->bus_no += 1; pci_default_write_config(pdev, PCI_SECONDARY_BUS, s->bus_no, 1); - do { - pdev = pci_get_bus(pdev)->parent_dev; - pci_default_write_config(pdev, PCI_SUBORDINATE_BUS, - s->bus_no, 1); - } while (pci_get_bus(pdev) && pci_dev_bus_num(pdev)); + + s390_pci_update_subordinate(pdev, s->bus_no); } } else if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) { pdev = PCI_DEVICE(dev);