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A mirror of the official Linux kernel repository just in case
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Paul Mackerras 19f8a5b5be powerpc/powernv: Don't reprogram SLW image on every KVM guest entry/exit 
Commit 24be85a23d ("powerpc/powernv: Clear PECE1 in LPCR via stop-api
only on Hotplug", 2017-07-21) added two calls to opal_slw_set_reg()
inside pnv_cpu_offline(), with the aim of changing the LPCR value in
the SLW image to disable wakeups from the decrementer while a CPU is
offline.  However, pnv_cpu_offline() gets called each time a secondary
CPU thread is woken up to participate in running a KVM guest, that is,
not just when a CPU is offlined.

Since opal_slw_set_reg() is a very slow operation (with observed
execution times around 20 milliseconds), this means that an offline
secondary CPU can often be busy doing the opal_slw_set_reg() call
when the primary CPU wants to grab all the secondary threads so that
it can run a KVM guest.  This leads to messages like "KVM: couldn't
grab CPU n" being printed and guest execution failing.

There is no need to reprogram the SLW image on every KVM guest entry
and exit.  So that we do it only when a CPU is really transitioning
between online and offline, this moves the calls to
pnv_program_cpu_hotplug_lpcr() into pnv_smp_cpu_kill_self().

Fixes: 24be85a23d ("powerpc/powernv: Clear PECE1 in LPCR via stop-api only on Hotplug")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-02-22 00:10:15 +11:00
arch powerpc/powernv: Don't reprogram SLW image on every KVM guest entry/exit 2019-02-22 00:10:15 +11:00
block block: fix kerneldoc comment for blk_attempt_plug_merge() 2019-01-09 15:29:08 -07:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
Documentation ARM: SoC fixes 2019-01-14 10:34:14 +12:00
drivers Merge branch 'topic/dma' into next 2019-02-21 23:15:10 +11:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs for-5.0-rc1-tag 2019-01-14 05:55:51 +12:00
include swiotlb: remove swiotlb_dma_supported 2019-02-18 22:41:04 +11:00
init jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Merge branch 'topic/dma' into next 2019-02-21 23:15:10 +11:00
lib Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
mm mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one 2019-01-10 02:58:21 -08:00
net libceph: allow setting abort_on_full for rbd 2019-01-07 22:47:48 +01:00
samples samples/seccomp: Fix 32-bit build 2019-01-08 07:45:01 +01:00
scripts remove dma_zalloc_coherent 2019-01-12 10:52:40 -08:00
security Merge branch 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-01-05 13:25:58 -08:00
sound remove dma_zalloc_coherent 2019-01-12 10:52:40 -08:00
tools Merge branch 'fixes' into next 2019-02-19 19:56:26 +11:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt KVM: validate userspace input in kvm_clear_dirty_log_protect() 2019-01-11 18:38:07 +01:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Add CREDITS entry for Shaohua Li 2019-01-04 14:27:09 -07:00
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Staging driver fixes for 5.0-rc2 2019-01-14 05:49:35 +12:00
Makefile Linux 5.0-rc2 2019-01-14 10:41:12 +12:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.