[SRU][Xenial][PATCH 0/1] KVM: PPC: Book3S: Treat VTB as a per-subcore register, not per-thread

Joseph Salisbury joseph.salisbury at canonical.com
Fri Nov 3 17:05:43 UTC 2017


BugLink: http://bugs.launchpad.net/bugs/1727331

== SRU Justification ==
Xenial does not include the patch: 
"KVM: PPC: Book3S: Treat VTB as a per-subcore register, not per-thread", 
which is commit 88b02cf97bb7 in the upstream Linux kernel repository. The 
symptom of not having this patch is that guests running with threads > 1 
(that is, in SMT2, SMT4 or SMT8 mode) can give spurious soft-lockup messages 
when they are not in fact locked up, if the guest kernel uses the VTB 
(virtual timebase) register in its softlockup detector code.

IBM provided this backport of commit 88b02cf97bb7.
    
== Fix ==
commit 88b02cf97bb7e742db3e31671d54177e3e19fd89
Author: Paul Mackerras <paulus at ozlabs.org>
Date:   Thu Sep 15 13:42:52 2016 +1000

    KVM: PPC: Book3S: Treat VTB as a per-subcore register, not per-thread

== Regression Potential ==
This patch is specific to powerpc.  It was provided by and tested by IBM.

== Test Case ==
A test kernel was built with this patch and tested by the original bug reporter.
The bug reporter states the test kernel resolved the bug.

Paul Mackerras (1):
  KVM: PPC: Book3S: Treat VTB as a per-subcore register, not per-thread

 arch/powerpc/include/asm/kvm_book3s.h   |  1 +
 arch/powerpc/include/asm/kvm_host.h     |  2 +-
 arch/powerpc/kernel/asm-offsets.c       |  2 +-
 arch/powerpc/kvm/book3s.c               |  6 ------
 arch/powerpc/kvm/book3s_emulate.c       |  2 +-
 arch/powerpc/kvm/book3s_hv.c            | 14 +++++++++++---
 arch/powerpc/kvm/book3s_hv_rmhandlers.S | 14 +++++++-------
 arch/powerpc/kvm/book3s_pr.c            |  8 +++++++-
 8 files changed, 29 insertions(+), 20 deletions(-)

-- 
2.7.4





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