mirror of
https://github.com/xemu-project/xemu.git
synced 2024-11-23 19:49:43 +00:00
docs: updates on the POWER9 XIVE interrupt controller documentation
This includes various small updates and a better description of the chosen interrupt mode resulting from the combination of the 'ic-mode' machine option, the 'kernel_irqchip' option, guest support and KVM support. Signed-off-by: Cédric Le Goater <clg@kaod.org> Message-Id: <20190612160425.27670-1-clg@kaod.org> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Cédric Le Goater
David Gibson
parent
fad189d1f6
commit
b87a0100cd
@ -34,19 +34,118 @@ CAS Negotiation
|
||||
---------------
|
||||
|
||||
QEMU advertises the supported interrupt modes in the device tree
|
||||
property "ibm,arch-vec-5-platform-support" in byte 23 and the OS
|
||||
Selection for XIVE is indicated in the "ibm,architecture-vec-5"
|
||||
property ``ibm,arch-vec-5-platform-support`` in byte 23 and the OS
|
||||
Selection for XIVE is indicated in the ``ibm,architecture-vec-5``
|
||||
property byte 23.
|
||||
|
||||
The interrupt modes supported by the machine depend on the CPU type
|
||||
(POWER9 is required for XIVE) but also on the machine property
|
||||
``ic-mode`` which can be set on the command line. It can take the
|
||||
following values: ``xics``, ``xive``, ``dual`` and currently ``xics``
|
||||
is the default but it may change in the future.
|
||||
following values: ``xics``, ``xive``, and ``dual`` which is the
|
||||
default mode. ``dual`` means that both modes XICS **and** XIVE are
|
||||
supported and if the guest OS supports XIVE, this mode will be
|
||||
selected.
|
||||
|
||||
The choosen interrupt mode is activated after a reconfiguration done
|
||||
in a machine reset.
|
||||
|
||||
KVM negotiation
|
||||
---------------
|
||||
|
||||
When the guest starts under KVM, the capabilities of the host kernel
|
||||
and QEMU are also negotiated. Depending on the version of the host
|
||||
kernel, KVM will advertise the XIVE capability to QEMU or not.
|
||||
|
||||
Nevertheless, the available interrupt modes in the machine should not
|
||||
depend on the XIVE KVM capability of the host. On older kernels
|
||||
without XIVE KVM support, QEMU will use the emulated XIVE device as a
|
||||
fallback and on newer kernels (>=5.2), the KVM XIVE device.
|
||||
|
||||
As a final refinement, the user can also switch the use of the KVM
|
||||
device with the machine option ``kernel_irqchip``.
|
||||
|
||||
|
||||
XIVE support in KVM
|
||||
~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
For guest OSes supporting XIVE, the resulting interrupt modes on host
|
||||
kernels with XIVE KVM support are the following:
|
||||
|
||||
============== ============= ============= ================
|
||||
ic-mode kernel_irqchip
|
||||
-------------- ----------------------------------------------
|
||||
/ allowed off on
|
||||
(default)
|
||||
============== ============= ============= ================
|
||||
dual (default) XIVE KVM XIVE emul. XIVE KVM
|
||||
xive XIVE KVM XIVE emul. XIVE KVM
|
||||
xics XICS KVM XICS emul. XICS KVM
|
||||
============== ============= ============= ================
|
||||
|
||||
For legacy guest OSes without XIVE support, the resulting interrupt
|
||||
modes are the following:
|
||||
|
||||
============== ============= ============= ================
|
||||
ic-mode kernel_irqchip
|
||||
-------------- ----------------------------------------------
|
||||
/ allowed off on
|
||||
(default)
|
||||
============== ============= ============= ================
|
||||
dual (default) XICS KVM XICS emul. XICS KVM
|
||||
xive QEMU error(3) QEMU error(3) QEMU error(3)
|
||||
xics XICS KVM XICS emul. XICS KVM
|
||||
============== ============= ============= ================
|
||||
|
||||
(3) QEMU fails at CAS with ``Guest requested unavailable interrupt
|
||||
mode (XICS), either don't set the ic-mode machine property or try
|
||||
ic-mode=xics or ic-mode=dual``
|
||||
|
||||
|
||||
No XIVE support in KVM
|
||||
~~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
For guest OSes supporting XIVE, the resulting interrupt modes on host
|
||||
kernels without XIVE KVM support are the following:
|
||||
|
||||
============== ============= ============= ================
|
||||
ic-mode kernel_irqchip
|
||||
-------------- ----------------------------------------------
|
||||
/ allowed off on
|
||||
(default)
|
||||
============== ============= ============= ================
|
||||
dual (default) XIVE emul.(1) XIVE emul. QEMU error (2)
|
||||
xive XIVE emul.(1) XIVE emul. QEMU error (2)
|
||||
xics XICS KVM XICS emul. XICS KVM
|
||||
============== ============= ============= ================
|
||||
|
||||
|
||||
(1) QEMU warns with ``warning: kernel_irqchip requested but unavailable:
|
||||
IRQ_XIVE capability must be present for KVM``
|
||||
(2) QEMU fails with ``kernel_irqchip requested but unavailable:
|
||||
IRQ_XIVE capability must be present for KVM``
|
||||
|
||||
|
||||
For legacy guest OSes without XIVE support, the resulting interrupt
|
||||
modes are the following:
|
||||
|
||||
============== ============= ============= ================
|
||||
ic-mode kernel_irqchip
|
||||
-------------- ----------------------------------------------
|
||||
/ allowed off on
|
||||
(default)
|
||||
============== ============= ============= ================
|
||||
dual (default) QEMU error(4) XICS emul. QEMU error(4)
|
||||
xive QEMU error(3) QEMU error(3) QEMU error(3)
|
||||
xics XICS KVM XICS emul. XICS KVM
|
||||
============== ============= ============= ================
|
||||
|
||||
(3) QEMU fails at CAS with ``Guest requested unavailable interrupt
|
||||
mode (XICS), either don't set the ic-mode machine property or try
|
||||
ic-mode=xics or ic-mode=dual``
|
||||
(4) QEMU/KVM incompatibility due to device destruction in reset. This
|
||||
needs to be addressed more cleanly with an error.
|
||||
|
||||
|
||||
XIVE Device tree properties
|
||||
---------------------------
|
||||
|
||||
@ -92,10 +191,11 @@ for both interrupt mode. The different ranges are defined as follow :
|
||||
- ``0x0000 .. 0x0FFF`` 4K CPU IPIs (only used under XIVE)
|
||||
- ``0x1000 .. 0x1000`` 1 EPOW
|
||||
- ``0x1001 .. 0x1001`` 1 HOTPLUG
|
||||
- ``0x1002 .. 0x10FF`` unused
|
||||
- ``0x1100 .. 0x11FF`` 256 VIO devices
|
||||
- ``0x1200 .. 0x127F`` 32 PHBs devices
|
||||
- ``0x1200 .. 0x127F`` 32x4 LSIs for PHB devices
|
||||
- ``0x1280 .. 0x12FF`` unused
|
||||
- ``0x1300 .. 0x1FFF`` PHB MSIs
|
||||
- ``0x1300 .. 0x1FFF`` PHB MSIs (dynamically allocated)
|
||||
|
||||
Monitoring XIVE
|
||||
---------------
|
||||
|
||||
@ -20,10 +20,11 @@ The XIVE IC is composed of three sub-engines, each taking care of a
|
||||
processing layer of external interrupts:
|
||||
|
||||
- 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.
|
||||
(SC). These are found in PCI PHBs, in the Processor Service
|
||||
Interface (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). It handles event coalescing and perform interrupt
|
||||
routing by matching an event source number with an Event
|
||||
|
||||
Loading…
Reference in New Issue
Block a user