From 160715e23b00c660f0dfee3f1bdc021f9693d222 Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Wed, 17 Apr 2019 13:57:36 +0100 Subject: [PATCH 19/24] s390x/pci: Fix primary bus number for PCI bridges RH-Author: Cornelia Huck Message-id: <20190417135741.25297-20-cohuck@redhat.com> Patchwork-id: 85800 O-Subject: [RHEL-8.1.0 qemu-kvm PATCH v2 19/24] s390x/pci: Fix primary bus number for PCI bridges Bugzilla: 1699070 RH-Acked-by: David Hildenbrand RH-Acked-by: Thomas Huth RH-Acked-by: Jens Freimann From: David Hildenbrand The primary bus number corresponds always to the bus number of the bus the bridge is attached to. Right now, if we have two bridges attached to the same bus (e.g. root bus) this is however not the case. The first bridge will have primary bus 0, the second bridge primary bus 1, which is wrong. Fix the assignment. While at it, drop setting the PCI_SUBORDINATE_BUS temporarily to 0xff. Setting it temporarily to that value (as discussed e.g. in [1]), is only relevant for a running system that probes the buses. The value is effectively unused for us just doing a DFS. Also add a comment why we have to reassign during every reset (which I found to be surprising. Please note that hotplugging of bridges is in general still broken, will be fixed next. [1] http://www.science.unitn.it/~fiorella/guidelinux/tlk/node76.html Reviewed-by: Thomas Huth Signed-off-by: David Hildenbrand Message-Id: <20190130155733.32742-2-david@redhat.com> Reviewed-by: Collin Walling Signed-off-by: Cornelia Huck (cherry picked from commit d30a7507edf1ca23d33dbf00b25f5e49a7808492) Signed-off-by: Cornelia Huck Signed-off-by: Danilo C. L. de Paula --- hw/s390x/s390-pci-bus.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c index 07a286a..309ad79 100644 --- a/hw/s390x/s390-pci-bus.c +++ b/hw/s390x/s390-pci-bus.c @@ -900,7 +900,8 @@ static void s390_pcihost_plug(HotplugHandler *hotplug_dev, DeviceState *dev, qbus_set_hotplug_handler(bus, DEVICE(s), errp); if (dev->hotplugged) { - pci_default_write_config(pdev, PCI_PRIMARY_BUS, s->bus_no, 1); + 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 { @@ -1053,8 +1054,6 @@ static void s390_pci_enumerate_bridge(PCIBus *bus, PCIDevice *pdev, void *opaque) { S390pciState *s = opaque; - unsigned int primary = s->bus_no; - unsigned int subordinate = 0xff; PCIBus *sec_bus = NULL; if ((pci_default_read_config(pdev, PCI_HEADER_TYPE, 1) != @@ -1063,7 +1062,7 @@ static void s390_pci_enumerate_bridge(PCIBus *bus, PCIDevice *pdev, } (s->bus_no)++; - pci_default_write_config(pdev, PCI_PRIMARY_BUS, primary, 1); + pci_default_write_config(pdev, PCI_PRIMARY_BUS, pci_dev_bus_num(pdev), 1); pci_default_write_config(pdev, PCI_SECONDARY_BUS, s->bus_no, 1); pci_default_write_config(pdev, PCI_SUBORDINATE_BUS, s->bus_no, 1); @@ -1072,7 +1071,7 @@ static void s390_pci_enumerate_bridge(PCIBus *bus, PCIDevice *pdev, return; } - pci_default_write_config(pdev, PCI_SUBORDINATE_BUS, subordinate, 1); + /* Assign numbers to all child bridges. The last is the highest number. */ pci_for_each_device(sec_bus, pci_bus_num(sec_bus), s390_pci_enumerate_bridge, s); pci_default_write_config(pdev, PCI_SUBORDINATE_BUS, s->bus_no, 1); @@ -1083,6 +1082,10 @@ static void s390_pcihost_reset(DeviceState *dev) S390pciState *s = S390_PCI_HOST_BRIDGE(dev); PCIBus *bus = s->parent_obj.bus; + /* + * When resetting a PCI bridge, the assigned numbers are set to 0. So + * on every system reset, we also have to reassign numbers. + */ s->bus_no = 0; pci_for_each_device(bus, pci_bus_num(bus), s390_pci_enumerate_bridge, s); } -- 1.8.3.1