pci: Abolish pci_find_root_bus()

pci_find_root_bus() takes a domain parameter.  Currently PCI root buses
with domain other than 0 can't be created, so this is more or less a long
winded way of retrieving the main PCI root bus.  Numbered domains don't
actually properly cover the (non x86) possibilities for multiple PCI root
buses, so this patch for now enforces the domain == 0 restriction in other
places to replace pci_find_root_bus() with an explicit
pci_find_primary_bus().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
pci: Use helper to find device's root bus in pci_find_domain()

Currently pci_find_domain() performs two functions - it locates the PCI
root bus above the given bus, then looks up that root bus's domain number.
This patch adds a helper function to perform the first task, finding the
root bus for a given PCI device.  This is then used in pci_find_domain().
This changes pci_find_domain()'s signature slightly, taking a PCIDevice
instead of a PCIBus - since all callers passed something of the form
dev->bus, this simplifies things slightly.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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>
pci: Add root bus argument to pci_get_bus_devfn()

pci_get_bus_devfn() interprets a full PCI address string to give a PCIBus *
and device/function number within that bus.  Currently it assumes it is
working on an address under the primary PCI root bus.  This patch extends
it to allow the caller to specify a root bus.  This might seem a little odd
since the supplied address can (theoretically) include a PCI domain number.
However, attempting to use a non-zero domain number there is currently an
error, so that shouldn't really cause problems.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
pci: Add root bus parameter to pci_nic_init()

At present, pci_nic_init() and pci_nic_init_nofail() assume that they will
only create a NIC under the primary PCI root.  As we add support for
multiple PCI roots, that may no longer be the case.  This patch adds a root
bus parameter to pci_nic_init() (and updates callers accordingly) to allow
the machine init code using it to specify the right PCI root for NICs
created by old-style -net nic parameters.  NICs created new-style, with
-device can of course be put anywhere.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
pci: Simpler implementation of primary PCI bus

Currently pci_find_primary_bus() searches the list of root buses for one
with domain 0.  But since host buses are always registered with domain 0,
this just amounts to finding the only PCI host bus.  The only remaining
users of pci_find_primary_bus() are in pci-hotplug-old.c, which implements
the old style pci_add/pci_del commands.

Therefore, this patch redefines pci_find_primary_bus() to find the only
PCI root bus, returning an error if there are multiple roots.  The callers
in pci-hotplug-old.c are updated correspondingly, to produce sensible
error messages.

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

There are now no users of the domain field of PCIHostBus, so remove it
from the structure, and as a parameter from the pci_host_bus_register()
function which sets it.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
pci: Fold host_buses list into PCIHostState functionality

The host_buses list is an odd structure - a list of pointers to PCI root
buses existing in parallel to the normal qdev tree structure.  This patch
removes it, instead putting the link pointers into the PCIHostState
structure, which have a 1:1 relationship to PCIHostBus structures anyway.

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