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pci: fix migration path for devices behind bridges 

The device path used for migration is currently broken for
for all devices behind a nested bridge.

Replace this by a hierarchical list of slot/function numbers, walking
the path from root down to device. Add :00 after the domain number
so that if there are no nested bridges, this is compatible
with what we have now.

Note: as pointed out by Gleb, using openfirmware paths
might be cleaner, doing this would break compatibility though,
and the IDs used are not guest or user visible at all,
so breaking the compatibility is probably not worth it.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2010-12-27 11:21:38 +02:00
parent 2ae63bda50
commit a6a7005d14
1 changed files with 35 additions and 9 deletions
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44
hw/pci.c
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@ -2014,17 +2014,43 @@ static char *pcibus_get_fw_dev_path(DeviceState *dev)
static char *pcibus_get_dev_path(DeviceState *dev)
{
PCIDevice *d = (PCIDevice *)dev;
char path[16];
PCIDevice *d = container_of(dev, PCIDevice, qdev);
PCIDevice *t;
int slot_depth;
/* Path format: Domain:00:Slot.Function:Slot.Function....:Slot.Function.
* 00 is added here to make this format compatible with
* 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. */
int domain_len = strlen("DDDD:00");
int slot_len = strlen(":SS.F");
int path_len;
char *path, *p;
snprintf(path, sizeof(path), "%04x:%02x:%02x.%x",
pci_find_domain(d->bus),
0 /* TODO: need a persistent path for nested buses.
* Note: pci_bus_num(d->bus) is not right as it's guest
* assigned. */,
PCI_SLOT(d->devfn), PCI_FUNC(d->devfn));
/* Calculate # of slots on path between device and root. */;
slot_depth = 0;
for (t = d; t; t = t->bus->parent_dev) {
++slot_depth;
}
return strdup(path);
path_len = domain_len + slot_len * slot_depth;
/* Allocate memory, fill in the terminating null byte. */
path = malloc(path_len + 1 /* For '\0' */);
path[path_len] = '\0';
/* First field is the domain. */
snprintf(path, domain_len, "%04x:00", pci_find_domain(d->bus));
/* Fill in slot numbers. We walk up from device to root, so need to print
* them in the reverse order, last to first. */
p = path + path_len;
for (t = d; t; t = t->bus->parent_dev) {
p -= slot_len;
snprintf(p, slot_len, ":%02x.%x", PCI_SLOT(t->devfn), PCI_FUNC(d->devfn));
}
return path;
}
static int pci_qdev_find_recursive(PCIBus *bus,