pci: Replace pci_find_domain() with more general pci_root_bus_path()

pci_find_domain() is used in a number of places where we want an id for a
whole PCI domain (i.e. the subtree under a PCI root bus).  The trouble is
that many platforms may support multiple independent host bridges with no
hardware supplied notion of domain number.

This patch, therefore, replaces calls to pci_find_domain() with calls to
a new pci_root_bus_path() returning a string.  The new call is implemented
in terms of a new callback in the host bridge class, so it can be defined
in some way that's well defined for the platform.  When no callback is
available we fall back on the qbus name.

Most current uses of pci_find_domain() are for error or informational
messages, so the change in identifiers should be harmless.  The exception
is pci_get_dev_path(), whose results form part of migration streams.  To
maintain compatibility with old migration streams, the PIIX PCI host is
altered to always supply "0000" for this path, which matches the old domain
number (since the code didn't actually support domains other than 0).

For the pseries (spapr) PCI bridge we use a different platform-unique
identifier (pseries machines can routinely have dozens of PCI host
bridges).  Theoretically that breaks migration streams, but given that we
don't yet have migration support for pseries, it doesn't matter.

Any other machines that have working migration support including PCI
devices will need to be updated to maintain migration stream compatibility.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

4 files changed, 27 insertions, 24 deletions

diff --git a/hw/pci/pci-hotplug-old.c b/hw/pci/pci-hotplug-old.c
index 37e0720..e251810 100644
--- a/hw/pci/pci-hotplug-old.c
+++ b/hw/pci/pci-hotplug-old.c
@@ -275,8 +275,8 @@ void pci_device_hot_add(Monitor *mon, const QDict *qdict)
     }
 
     if (dev) {
-        monitor_printf(mon, "OK domain %d, bus %d, slot %d, function %d\n",
-                       pci_find_domain(dev),
+        monitor_printf(mon, "OK root bus %s, bus %d, slot %d, function %d\n",
+                       pci_root_bus_path(dev),
                        pci_bus_num(dev->bus), PCI_SLOT(dev->devfn),
                        PCI_FUNC(dev->devfn));
     } else
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 69a6995..350b872 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -25,6 +25,7 @@
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_bridge.h"
 #include "hw/pci/pci_bus.h"
+#include "hw/pci/pci_host.h"
 #include "monitor/monitor.h"
 #include "net/net.h"
 #include "sysemu/sysemu.h"
@@ -270,19 +271,20 @@ PCIBus *pci_device_root_bus(const PCIDevice *d)
     return bus;
 }
 
-int pci_find_domain(const PCIDevice *dev)
+const char *pci_root_bus_path(PCIDevice *dev)
 {
-    const PCIBus *rootbus = pci_device_root_bus(dev);
-    struct PCIHostBus *host;
+    PCIBus *rootbus = pci_device_root_bus(dev);
+    PCIHostState *host_bridge = PCI_HOST_BRIDGE(rootbus->qbus.parent);
+    PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_GET_CLASS(host_bridge);
 
-    QLIST_FOREACH(host, &host_buses, next) {
-        if (host->bus == rootbus) {
-            return host->domain;
-        }
+    assert(!rootbus->parent_dev);
+    assert(host_bridge->bus == rootbus);
+
+    if (hc->root_bus_path) {
+        return (*hc->root_bus_path)(host_bridge, rootbus);
     }
 
-    abort();    /* should not be reached */
-    return -1;
+    return rootbus->qbus.name;
 }
 
 static void pci_bus_init(PCIBus *bus, DeviceState *parent,
@@ -2000,10 +2002,10 @@ int pci_add_capability(PCIDevice *pdev, uint8_t cap_id,
         for (i = offset; i < offset + size; i++) {
             overlapping_cap = pci_find_capability_at_offset(pdev, i);
             if (overlapping_cap) {
-                fprintf(stderr, "ERROR: %04x:%02x:%02x.%x "
+                fprintf(stderr, "ERROR: %s:%02x:%02x.%x "
                         "Attempt to add PCI capability %x at offset "
                         "%x overlaps existing capability %x at offset %x\n",
-                        pci_find_domain(pdev), pci_bus_num(pdev->bus),
+                        pci_root_bus_path(pdev), pci_bus_num(pdev->bus),
                         PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn),
                         cap_id, offset, overlapping_cap, i);
                 return -EINVAL;
@@ -2137,30 +2139,30 @@ static char *pcibus_get_dev_path(DeviceState *dev)
      * domain:Bus:Slot.Func for systems without nested PCI bridges.
      * Slot.Function list specifies the slot and function numbers for all
      * devices on the path from root to the specific device. */
-    char domain[] = "DDDD:00";
+    const char *root_bus_path;
+    int root_bus_len;
     char slot[] = ":SS.F";
-    int domain_len = sizeof domain - 1 /* For '\0' */;
     int slot_len = sizeof slot - 1 /* For '\0' */;
     int path_len;
     char *path, *p;
     int s;
 
+    root_bus_path = pci_root_bus_path(d);
+    root_bus_len = strlen(root_bus_path);
+
     /* Calculate # of slots on path between device and root. */;
     slot_depth = 0;
     for (t = d; t; t = t->bus->parent_dev) {
         ++slot_depth;
     }
 
-    path_len = domain_len + slot_len * slot_depth;
+    path_len = root_bus_len + slot_len * slot_depth;
 
     /* Allocate memory, fill in the terminating null byte. */
     path = g_malloc(path_len + 1 /* For '\0' */);
     path[path_len] = '\0';
 
-    /* First field is the domain. */
-    s = snprintf(domain, sizeof domain, "%04x:00", pci_find_domain(d));
-    assert(s == domain_len);
-    memcpy(path, domain, domain_len);
+    memcpy(path, root_bus_path, root_bus_len);
 
     /* Fill in slot numbers. We walk up from device to root, so need to print
      * them in the reverse order, last to first. */
diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
index 12254b1..7dd9b25 100644
--- a/hw/pci/pci_host.c
+++ b/hw/pci/pci_host.c
@@ -169,6 +169,7 @@ static const TypeInfo pci_host_type_info = {
     .name = TYPE_PCI_HOST_BRIDGE,
     .parent = TYPE_SYS_BUS_DEVICE,
     .abstract = true,
+    .class_size = sizeof(PCIHostBridgeClass),
     .instance_size = sizeof(PCIHostState),
 };
 
diff --git a/hw/pci/pcie_aer.c b/hw/pci/pcie_aer.c
index 06f77ac..ca762ab 100644
--- a/hw/pci/pcie_aer.c
+++ b/hw/pci/pcie_aer.c
@@ -817,9 +817,9 @@ void pcie_aer_inject_error_print(Monitor *mon, const QObject *data)
     qdict = qobject_to_qdict(data);
 
     devfn = (int)qdict_get_int(qdict, "devfn");
-    monitor_printf(mon, "OK id: %s domain: %x, bus: %x devfn: %x.%x\n",
+    monitor_printf(mon, "OK id: %s root bus: %s, bus: %x devfn: %x.%x\n",
                    qdict_get_str(qdict, "id"),
-                   (int) qdict_get_int(qdict, "domain"),
+                   qdict_get_str(qdict, "root_bus"),
                    (int) qdict_get_int(qdict, "bus"),
                    PCI_SLOT(devfn), PCI_FUNC(devfn));
 }
@@ -1020,9 +1020,9 @@ int do_pcie_aer_inject_error(Monitor *mon,
 
     ret = pcie_aer_inject_error(dev, &err);
     *ret_data = qobject_from_jsonf("{'id': %s, "
-                                   "'domain': %d, 'bus': %d, 'devfn': %d, "
+                                   "'root_bus': %s, 'bus': %d, 'devfn': %d, "
                                    "'ret': %d}",
-                                   id, pci_find_domain(dev),
+                                   id, pci_root_bus_path(dev),
                                    pci_bus_num(dev->bus), dev->devfn,
                                    ret);
     assert(*ret_data);