When starting an L2 KVM guest with `ic-mode=dual,kernel-irqchip=on`,
QEMU fails with:
KVM is too old to support ic-mode=dual,kernel-irqchip=on
This error message was introduced to detect older KVM versions that
didn't allow destruction and re-creation of the XICS KVM device that
we do at reboot. But it is actually the same issue that we get with
nested guests : when running under pseries, KVM currently provides
a genuine XICS device (not the XICS-on-XIVE device that we get
under powernv) which doesn't support destruction/re-creation.
This will eventually be fixed in KVM but in the meantime, update
the error message and documentation to mention the nested case.
While here, mention that in "No XIVE support in KVM" section that
this can also happen with "guest OSes supporting XIVE" since
we check this at init time before starting the guest.
Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Buglink: https://bugs.launchpad.net/qemu/+bug/1890290
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <159664243614.622889.18307368735989783528.stgit@bahia.lan>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
It is not yet supported.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20200804131639.407049-1-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Older KVMs on POWER9 don't support destroying/recreating a KVM XICS
device, which is required by 'dual' interrupt controller mode. This
causes QEMU to emit a warning when the guest is rebooted and to fall
back on XICS emulation:
qemu-system-ppc64: warning: kernel_irqchip allowed but unavailable:
Error on KVM_CREATE_DEVICE for XICS: File exists
If kernel irqchip is required, QEMU will thus exit when the guest is
first rebooted. Failing QEMU this late may be a painful experience
for the user.
Detect that and exit at machine init instead.
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <156044430517.125694.6207865998817342638.stgit@bahia.lab.toulouse-stg.fr.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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 documents the overall XIVE architecture and the XIVE support for
sPAPR guest machines (pseries).
It also provides documentation on the 'info pic' command.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20190521082411.24719-1-clg@kaod.org>
Reviewed-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
