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Benjamin Herrenschmidt ad98dd1a75 KVM: PPC: Book3S HV: Add more barriers in XIVE load/unload code
On POWER9 systems, we push the VCPU context onto the XIVE (eXternal
Interrupt Virtualization Engine) hardware when entering a guest,
and pull the context off the XIVE when exiting the guest.  The push
is done with cache-inhibited stores, and the pull with cache-inhibited
loads.

Testing has revealed that it is possible (though very rare) for
the stores to get reordered with the loads so that we end up with the
guest VCPU context still loaded on the XIVE after we have exited the
guest.  When that happens, it is possible for the same VCPU context
to then get loaded on another CPU, which causes the machine to
checkstop.

To fix this, we add I/O barrier instructions (eieio) before and
after the push and pull operations.  As partial compensation for the
potential slowdown caused by the extra barriers, we remove the eieio
instructions between the two stores in the push operation, and between
the two loads in the pull operation.  (The architecture requires
loads to cache-inhibited, guarded storage to be kept in order, and
requires stores to cache-inhibited, guarded storage likewise to be
kept in order, but allows such loads and stores to be reordered with
respect to each other.)

Reported-by: Carol L Soto <clsoto@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
2017-10-16 08:46:46 +11:00
arch KVM: PPC: Book3S HV: Add more barriers in XIVE load/unload code 2017-10-16 08:46:46 +11:00
block bsg-lib: fix use-after-free under memory-pressure 2017-10-04 08:35:04 -06:00
certs
crypto
Documentation Merge branch 'i2c/for-current-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2017-10-07 10:07:51 -07:00
drivers SCSI fixes on 20171007 2017-10-07 12:34:16 -07:00
firmware
fs Changes since last update: 2017-10-06 15:53:36 -07:00
include SCSI fixes on 20171007 2017-10-07 12:34:16 -07:00
init
ipc
kernel Merge branch 'core-watchdog-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-10-06 08:36:41 -07:00
lib
mm
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-05 08:40:09 -07:00
samples
scripts
security
sound sound fixes for 4.14-rc4 2017-10-05 10:39:29 -07:00
tools
usr
virt
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap Update James Hogan's email address 2017-10-04 17:11:53 -07:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS ARC udpates for 4.14-rc4 2017-10-06 15:57:08 -07:00
Makefile Linux 4.14-rc4 2017-10-08 20:53:29 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.