ACK/Cmnt: [SRU][Bionic][PATCH 0/2] Fixes for LP:1773162

[Stefan Bader]

On 25.05.2018 15:39, Joseph Salisbury wrote:
> BugLink: http://bugs.launchpad.net/bugs/1773162
> 
> == SRU Justification ==
> IBM reports that 4.15.0-22-generic fails to boot on IBM S822LC (POWER8 
> (raw), altivec supported).  The system then gets stuck in a reboot
> cycle.
> 
> It was found that Bionic commit 06f7e3d39f2f was the cause of this
> regression.  IBM believes the backport of this commit for CVE-2018-3639 (powerpc) was
> done incorrectly.  
> 
> I reverted the backport of commit 06f7e3d39f2f.  I then performed a new
> backport of mainline commit a048a07d7f45.  I built a test kernel for IBM
> who tested this kernel.  It was reported this new backport resolves the
> bug.
> 
> == Fixes ==
> Revert "powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit"
> a048a07d7f45 ("powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit")
> 
> == Regression Potential ==
> Low.  Fixes a regression and limited to powerpc.
> 
> == Test Case ==
> A test kernel was built with the revert and second backport. IBM tested
> this new patch and stated the test kernel resolved the bug.
> 
> Joseph Salisbury (1):
>   Revert "powerpc/64s: Add support for a store forwarding barrier at
>     kernel entry/exit"
> 
> Nicholas Piggin (1):
>   powerpc/64s: Add support for a store forwarding barrier at kernel
>     entry/exit
> 
>  arch/powerpc/include/asm/exception-64s.h     |   6 +-
>  arch/powerpc/include/asm/security_features.h |  11 ++
>  arch/powerpc/include/asm/setup.h             |  12 +--
>  arch/powerpc/kernel/security.c               | 149 +++++++++++++++++++++++++++
>  arch/powerpc/kernel/setup_64.c               | 119 +--------------------
>  arch/powerpc/lib/feature-fixups.c            |  16 ++-
>  arch/powerpc/platforms/powernv/setup.c       |   2 +-
>  7 files changed, 183 insertions(+), 132 deletions(-)
> 
Looking at the complete delta (revert + new patch applied) it rather feels like
the patch we had was some older variant of the current one. But given this got
successful testing:

Acked-by: Stefan Bader <stefan.bader at canonical.com>
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