cbc06f051c
On PowerVM, CPU-less nodes can be populated with hot-plugged CPUs at
runtime. Today, the IPI is not created for such nodes, and hot-plugged
CPUs use a bogus IPI, which leads to soft lockups.
We can not directly allocate and request the IPI on demand because
bringup_up() is called under the IRQ sparse lock. The alternative is
to allocate the IPIs for all possible nodes at startup and to request
the mapping on demand when the first CPU of a node is brought up.
Fixes: 7dcc37b3ef ("powerpc/xive: Map one IPI interrupt per node")
Cc: stable@vger.kernel.org # v5.13
Reported-by: Geetika Moolchandani <Geetika.Moolchandani1@ibm.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210807072057.184698-1-clg@kaod.org
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.