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4edaac512c
Normally, the HV emulates some instructions like MSGSNDP, MSGCLRP from a KVM guest. To emulate the instructions, it must first read the instruction from the guest's memory and decode its parameters. However for a secure guest (aka SVM), the page containing the instruction is in secure memory and the HV cannot access directly. It would need the Ultravisor (UV) to facilitate accessing the instruction and parameters but the UV currently does not have the support for such accesses. Until the UV has such support, disable doorbells in SVMs. This might incur a performance hit but that is yet to be quantified. With this patch applied (needed only in SVMs not needed for HV) we are able to launch SVM guests with multi-core support. Eg: qemu -smp sockets=2,cores=2,threads=2. Fix suggested by Benjamin Herrenschmidt. Thanks to input from Paul Mackerras, Ram Pai and Michael Anderson. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190820021326.6884-13-bauerman@linux.ibm.com
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.