docs: add sPAPR hotplug/dynamic-reconfiguration documentation

This adds a general overview of hotplug/dynamic-reconfiguration
for sPAPR/pSeries guest.

As specified in PAPR+ v2.7.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_drc: initial implementation of sPAPRDRConnector device

This device emulates a firmware abstraction used by pSeries guests to
manage hotplug/dynamic-reconfiguration of host-bridges, PCI devices,
memory, and CPUs. It is conceptually similar to an SHPC device,
complete with LED indicators to identify individual slots to physical
physical users and indicate when it is safe to remove a device. In
some cases it is also used to manage virtualized resources, such a
memory, CPUs, and physical-host bridges, which in the case of pSeries
guests are virtualized resources where the physical components are
managed by the host.

Guests communicate with these DR Connectors using RTAS calls,
generally by addressing the unique DRC index associated with a
particular connector for a particular resource. For introspection
purposes we expose this state initially as QOM properties, and
in subsequent patches will introduce the RTAS calls that make use of
it. This constitutes to the 'guest' interface.

On the QEMU side we provide an attach/detach interface to associate
or cleanup a DeviceState with a particular sPAPRDRConnector in
response to hotplug/unplug, respectively. This constitutes the
'physical' interface to the DR Connector.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
*spapr_drc: improve debug, clean up unused code
*spapr_drc: clean up unused code
*spapr_drc: fix entity_sense
spapr_rtas: add get/set-power-level RTAS interfaces

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_rtas: add set-indicator RTAS interface

Signed-off-by: Mike Day <ncmike@ncultra.org>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_rtas: add get-sensor-state RTAS interface

Signed-off-by: Mike Day <ncmike@ncultra.org>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr: add rtas_st_buffer_direct() helper

This is similar to the existing rtas_st_buffer(), but for case where
the guest is not expecting a length-encoded byte array. Namely,
for calls where an "work area" buffer is used to pass around
arbitrary fields/data.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_rtas: add ibm,configure-connector RTAS interface

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_events: re-use EPOW event infrastructure for hotplug events

This extends the data structures currently used to report EPOW events to
gets via the check-exception RTAS interfaces to also include event types
for hotplug/unplug events.

This is currently undocumented and being finalized for inclusion in PAPR
specification, but we implement this here as an extension for guest
userspace tools to implement (existing guest kernels simply log these
events via a sysfs interface that's read by rtas_errd).

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_events: event-scan RTAS interface

We don't actually rely on this interface to surface hotplug events, and
instead rely on the similar-but-interrupt-driven check-exception RTAS
interface used for EPOW events. However, the existence of this interface
is needed to ensure guest kernels initialize the event-reporting
interfaces which will in turn be used by userspace tools to handle these
events, so we implement this interface as a stub.

Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_drc: add spapr_drc_populate_dt()

This function handles generation of ibm,drc-* array device tree
properties to describe DRC topology to guests. This will by used
by the guest to direct RTAS calls to manage any dynamic resources
we associate with a particular DR Connector as part of
hotplug/unplug.

Since general management of boot-time device trees are handled
outside of sPAPRDRConnector, we insert these values blindly given
an FDT and offset. A mask of sPAPRDRConnector types is given to
instruct us on what types of connectors entries should be generated
for, since descriptions for different connectors may live in
different parts of the device tree.

Based on code originally written by Nathan Fontenot.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr: introduce pseries-2.3 machine type

And make it the default. This is identical to pseries-2.2 for now,
but subsequent commits will use it to enable pseries-2.3+ features.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_pci: add dynamic-reconfiguration option for spapr-pci-host-bridge

This option enables/disables PCI hotplug for a particular PHB.

Also add machine compatibility code to disable it by default for machine
types prior to pseries-2.3.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_pci: create DRConnectors for each PCI slot during PHB realize

These will be used to support hotplug/unplug of PCI devices to the PCI
bus associated with a particular PHB.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_pci: populate DRC dt entries for PHBs

Reserve 32 entries of type PCI in each PHB's initial FDT. This
advertises to guests that each PHB is DR-capable device with
physical hotpluggable slots. This is necessary for allowing
hotplugging of devices to it later via bus rescan or guest rpaphp
hotplug module.

Each entry is assigned a name of "Slot <<bus_idx>*32 +1>",
advertised as a hotpluggable PCI slot, and assigned to power domain
-1 to indicate to the guest that power management is handled by the
hardware.

This models a DR-capable PCI expansion device attached to a host/lpar
via a single PHB with 32 physical hotpluggable slots (as opposed to a
virtual bridge device with external management console). Hotplug will
be handled by the guest via bus rescan or the rpaphp hotplug module.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
pci: allow 0 address for PCI IO regions

Some kernels program a 0 address for io regions. PCI 3.0 spec
section 6.2.5.1 doesn't seem to disallow this.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
pci: make pci_bar useable outside pci.c

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_pci: enable basic hotplug operations

This enables hotplug for PHB bridges. Upon hotplug we generate the
OF-nodes required by PAPR specification and IEEE 1275-1994
"PCI Bus Binding to Open Firmware" for the device.

We associate the corresponding FDT for these nodes with the DrcEntry
corresponding to the slot, which will be fetched via
ibm,configure-connector RTAS calls by the guest as described by PAPR
specification. The FDT is cleaned up in the case of unplug.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>