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[Qemu-devel] [PATCH v4 00/28] ppc: support for the XIVE interrupt contro
Cédric Le Goater
[Qemu-devel] [PATCH v4 00/28] ppc: support for the XIVE interrupt controller (POWER9)
Thu, 7 Jun 2018 17:49:35 +0200
Here is the version 4 of the QEMU models adding support for XIVE to
the sPAPR machine, under TCG and KVM, and to the PowerNV machine. The
common framework is stabilizing and the routing is significantly
improved. The next interesting step would be to add escalation events
and model VP dispatching.
Changes in v4 :
Common XIVE models :
- minor changes in the XiveSource model. Remove unnecessary 'offset',
full IRQ number space is populated.
- reduced XiveFabric. The interface was embedding the Router which
- renamed XiveNVT to XiveTCTX for the Thread interrupt context.
- removed the CPU EQDs from under the Thread interrupt context
model. That was pratical but slightly ugly.
- unified the TIMA load/store accessors for sPAPR and PowerNV. It
supports all the TIMA privilege pages now.
- introduced a XiveRouter abstract class combining the IVRE and the
IVPE in one model. Storage for the routing tables should be
provisioned by the inheriting classes : sPAPRXive, PnvXive
- extended the routing algorithm. Covers all models and defines a
clear sequence of each steps.
- introduced a VP matching algorithm using the CAM lines as in real HW.
- introduced a new XiveEQSource model to expose the EQ ESBs. Not used
on the field, only to sync the EQ cache in OPAL.
On the sPAPR side :
- moved the EQDT under sPAPRXive, requires EQ indexing.
- new sPAPR IRQ backend for XIVE
- new pseries-2.13-xive machine supporting only XIVE.
- removed the capacity to switch the interrupt mode after CAS. Will
come in time when the models have stabilized. This is not a large
rework, the main problem being KVM reset.
- improved migration algo. Still misses OPAL calls to sync XIVE.
On the PowerNV side :
- A massive rework of PnvXive to adapt to the changes
- unified VST accessors
- multichip support
= XIVE =================================================================
The POWER9 processor comes with a new interrupt controller, called
XIVE as "eXternal Interrupt Virtualization Engine".
* Overall architecture
XIVE Interrupt Controller
| +---------+ +---------+ +---------+ | +--------+
| |VC | |CQ | |PC |----> | CORES |
| | esb | | | | |----> | |
| | ive | | Bridge | | |----> | |
| |SC eqd | | | | vpd | | | |
+------+ | +---------+ +----+----+ +---------+ | +--+-+-+-+
| RAM | +------------------|------------------+ | | |
| | | | | |
| | | | | |
| | +---------------------v--------------------------v-v-v---+ other
| <---+ Power Bus +----> chips
| esb | +-----------+-----------------------+--------------------+
| ive | | |
| eqd | | |
| vpd | +---+----+ +---+----+
+------+ |SC | |SC |
| | | |
| 2-bits | | 2-bits |
| local | | VC |
SC: Source Controller (aka. IVSE)
VC: Virtualization Controller (aka. IVRE)
CQ: Common Queue (Bridge)
PC: Presentation Controller (aka. IVPE)
2-bits: source state machine
esb: Event State Buffer (Array of PQ bits in an IVSE)
ive: Interrupt Virtualization Entry
eqd: Event Queue Descriptor
vpd: Virtual Processor Descriptor
It is composed of three sub-engines :
- Interrupt Virtualization Source Engine (IVSE), or Source
Controller (SC). These are found in PCI PHBs, in the PSI host
bridge controller, but also inside the main controller for the
core IPIs and other sub-chips (NX, CAP, NPU) of the
chip/processor. They are configured to feed the IVRE with events.
- Interrupt Virtualization Routing Engine (IVRE) or Virtualization
Controller (VC). Its job is to match an event source with an Event
- Interrupt Virtualization Presentation Engine (IVPE) or Presentation
Controller (PC). It maintains the interrupt context state of each
thread and handles the delivery of the external exception to the
* XIVE internal tables
Each of the sub-engines uses a set of tables to redirect exceptions
from event sources to CPU threads.
User or OS | EQ |
Hypervisor | | .. |
Memory | +-------+
Hypervisor +------+ +---+--+ +---+--+ +------+
Memory | ESB | | IVT | | EQDT | | VPDT |
(skiboot) +----+-+ +----+-+ +----+-+ +------+
^ | ^ | ^ | ^
| | | | | | |
| | | | | | |
| | | | | | |
+-----|--|--------|--|--------|--|-+ +-|-----+ +------+
| | | | | | | | | | tctx| |Thread|
IPI or ----+ + v + v + v |---| + .. |-----> |
HW events | | | | | |
| IVRE | | IVPE | +------+
The IVSE have a 2-bits, P for pending and Q for queued, state machine
for each source that allows events to be triggered. They are stored in
an array, the Event State Buffer (ESB) and controlled by MMIOs.
If the event is let through, the IVRE looks up in the Interrupt
Virtualization Entry (IVE) table for an Event Queue Descriptor (EQD)
configured for the source. Each Event Queue Descriptor defines a
notification path to a CPU and an in-memory Event Queue, in which will
be pushed an EQ data for the OS to pull.
The IVPE determines if a Virtual Processor (VP) can handle the event
by scanning the thread contexts of the VPs dispatched on the processor
HW threads. It maintains the interrupt context state of each thread in
a Virtual Processor Descriptor (VPD) table.
* Overview of the QEMU models for the XIVE sub-engines
The XiveSource models the IVSE in general, internal and external. It
handles the source ESBs and the MMIO interface to control them.
The XiveFabric is a small helper interface interconnecting the
XiveSource to the XiveRouter.
The XiveRouter is an abstract model acting as a combined IVRE and
IVPE. It routes event notifications using the IVE and EQD tables to
the IVPE sub-engine which does a CAM scan to find a CPU to deliver the
exception. Storage should be provided by the inheriting classes.
XiveEQSource is a special source object. It exposes the EQ ESB MMIOs of
the Event Queues which are used for coalescing event notifications and
for escalation. Not used on the field, only to sync the EQ cache in
Finally, the XiveTCTX contains the interrupt state context of a thread,
four sets of registers, one for each exception that can be delivered
to a CPU. These contexts are scanned by the IVPE to find a matching VP
when a notification is triggered. It also models the Thread Interrupt
Management Area (TIMA), which exposes the thread context registers to
the CPU for interrupt management.
* XIVE for sPAPR
sPAPRXive models the XIVE interrupt controller of a sPAPR machine. It
inherits from the XiveRouter and provisions storage for the IVE and
EQD tables. The VPD table does not need a backend in sPAPR. It owns a
XiveSource object for the IPIs and the virtual device interrupts, a
memory region for the TIMA and a XiveEQSource to manage the EQ ESBs.
(not used by Linux).
These choices were made to have a sPAPR interrupt controller
consistent with the one found on baremetal and to facilitate KVM
support, the main difficulty being the host memory regions exposed to
The VP and EQ indexing needs some care and a set of helpers are
defined to ease the conversion between the CPU id as seen by the guest
and the identifiers manipulated by the models.
* Integration in the sPAPR machine
A new sPAPR IRQ backend is defined for XIVE. It introduces a couple of
new operations to handle the differences in the creation of the device
tree and in the allocation of the CPU interrupt controller. A new
XIVE-only machine is defined with the XIVE backend.
Changing interrupt mode as negotiated through CAS, to switch between
the XICS legacy model and XIVE, is obviously not supported. The sPAPR
IRQ backend framework should make the changes easier in the future.
* KVM support
Support for KVM introduces a set of specific XIVE models, very much
like XICS does, which self-connect to their KVM counterparts in the
Linux kernel. Two host memory regions are exposed to the guest and
need special care at initialization :
- ESB mmios
- Thread Interrupt Management Area (TIMA)
The models uses KVM accessors to synchronize the QEMU state with KVM.
Hybrid guest using KVM and an emulated irqchip (kernel_irqchip=off) is
Migration is also supported but some synchronisation points are
possibly needed to turn off/on XIVE and make sure all HW states are
captured correctly. Stress tests will say.
* PowerNV models
The PnvXIVE model now uses the XiveRouter abstract model just like
sPAPRXive does. It provides accessors to the IVE, EQD and VPD tables
which are stored in the QEMU powernv machine and not in QEMU anymore.
It owns a set of memory regions for the IC registers, the ESBs, the EQ
ESBs, the TIMA, the notification MMIO.
Multichip is supported and the available IVSEs are the internal one
for the IPIS and the PSI host bridge controller.
* GitHub trees
Linux/KVM (to be sent later on):
Cédric Le Goater (28):
sparp_pci: simplify how the PCI LSIs are allocated
spapr: introduce a generic IRQ frontend to the machine
spapr: introduce a new IRQ backend using fixed IRQ number ranges
ppc/xive: introduce a XIVE interrupt source model
ppc/xive: add support for the LSI interrupt sources
ppc/xive: introduce the XiveFabric interface
ppc/xive: introduce the XiveRouter model
ppc/xive: introduce the XIVE Event Queues
ppc/xive: add support for the EQ Event State buffers
ppc/xive: introduce the XIVE interrupt thread context
ppc/xive: introduce a simplified XIVE presenter
ppc/xive: notify the CPU when the interrupt priority is more
spapr/xive: introduce a XIVE interrupt controller
spapr/xive: use the VCPU id as a VP identifier in the OS CAM.
spapr: initialize VSMT before initializing the IRQ backend
spapr: introdude a new machine IRQ backend for XIVE
spapr: add hcalls support for the XIVE exploitation interrupt mode
spapr: add device tree support for the XIVE exploitation mode
spapr: allocate the interrupt thread context under the CPU core
spapr: introduce a 'pseries-3.0-xive' QEMU machine
spapr: add classes for the XIVE models
target/ppc/kvm: add Linux KVM definitions for XIVE
spapr/xive: add common realize routine for KVM
spapr/xive: add KVM support
spapr: fix XICS migration
pnv: add a physical mapping array describing MMIO ranges in each chip
ppc: externalize ppc_get_vcpu_by_pir()
ppc/pnv: add XIVE support
default-configs/ppc64-softmmu.mak | 3 +
hw/intc/pnv_xive_regs.h | 314 +++++++
include/hw/ppc/pnv.h | 71 +-
include/hw/ppc/pnv_xive.h | 92 ++
include/hw/ppc/pnv_xscom.h | 3 +
include/hw/ppc/ppc.h | 1 +
include/hw/ppc/spapr.h | 31 +-
include/hw/ppc/spapr_irq.h | 69 ++
include/hw/ppc/spapr_xive.h | 102 +++
include/hw/ppc/xive.h | 323 +++++++
include/hw/ppc/xive_regs.h | 182 ++++
include/migration/vmstate.h | 1 +
linux-headers/asm-powerpc/kvm.h | 23 +
linux-headers/linux/kvm.h | 3 +
target/ppc/kvm_ppc.h | 6 +
hw/intc/pnv_xive.c | 1485 ++++++++++++++++++++++++++++++
hw/intc/spapr_xive.c | 432 +++++++++
hw/intc/spapr_xive_hcall.c | 949 +++++++++++++++++++
hw/intc/spapr_xive_kvm.c | 809 +++++++++++++++++
hw/intc/xive.c | 1801 +++++++++++++++++++++++++++++++++++++
hw/ppc/pnv.c | 111 ++-
hw/ppc/pnv_core.c | 28 +-
hw/ppc/pnv_psi.c | 15 +-
hw/ppc/pnv_xscom.c | 8 +-
hw/ppc/ppc.c | 16 +
hw/ppc/spapr.c | 276 ++----
hw/ppc/spapr_cpu_core.c | 4 +-
hw/ppc/spapr_events.c | 8 +-
hw/ppc/spapr_irq.c | 834 +++++++++++++++++
hw/ppc/spapr_pci.c | 40 +-
hw/ppc/spapr_vio.c | 17 +-
target/ppc/kvm.c | 7 +
hw/intc/Makefile.objs | 5 +-
hw/ppc/Makefile.objs | 2 +-
34 files changed, 7768 insertions(+), 303 deletions(-)
create mode 100644 hw/intc/pnv_xive_regs.h
create mode 100644 include/hw/ppc/pnv_xive.h
create mode 100644 include/hw/ppc/spapr_irq.h
create mode 100644 include/hw/ppc/spapr_xive.h
create mode 100644 include/hw/ppc/xive.h
create mode 100644 include/hw/ppc/xive_regs.h
create mode 100644 hw/intc/pnv_xive.c
create mode 100644 hw/intc/spapr_xive.c
create mode 100644 hw/intc/spapr_xive_hcall.c
create mode 100644 hw/intc/spapr_xive_kvm.c
create mode 100644 hw/intc/xive.c
create mode 100644 hw/ppc/spapr_irq.c
- [Qemu-devel] [PATCH v4 00/28] ppc: support for the XIVE interrupt controller (POWER9),
Cédric Le Goater <=
- [Qemu-devel] [PATCH v4 01/28] sparp_pci: simplify how the PCI LSIs are allocated, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 02/28] spapr: introduce a generic IRQ frontend to the machine, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 03/28] spapr: introduce a new IRQ backend using fixed IRQ number ranges, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 04/28] ppc/xive: introduce a XIVE interrupt source model, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 05/28] ppc/xive: add support for the LSI interrupt sources, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 06/28] ppc/xive: introduce the XiveFabric interface, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 07/28] ppc/xive: introduce the XiveRouter model, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 08/28] ppc/xive: introduce the XIVE Event Queues, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 09/28] ppc/xive: add support for the EQ Event State buffers, Cédric Le Goater, 2018/06/07
- [Qemu-devel] [PATCH v4 10/28] ppc/xive: introduce the XIVE interrupt thread context, Cédric Le Goater, 2018/06/07