[SRU][Xenial][Yakkety][PATCH 0/1] UBUNTU: SAUCE: (no-up) x86/topology: Handle CPUID bogosity gracefully

[Joseph Salisbury]

On 05/09/2016 12:17 PM, Joseph Salisbury wrote:
> BugLink: http://bugs.launchpad.net/bugs/1573231
>
> == Xenial and Yakkety Justification ==
> Multiple users have reported a Kernel Panic on EC2 After Upgrading from 14.04 to 16.04.
> After a bisect it was found that commit 8ae10f463b introduced this bug.  
>
> The panic is due to a a divide error. The divide error happens because XEN is supplying bogus 
> data in the CPUID.
>
> Thomas Gleixner created a patch to solve this bug.  The patch is in the x86 tree and has
> been submitted for inclusion in mainline.
>
> This patch is marked as SAUCE and (no-up) because it has not landed in mainline as 
> of yet.  However, it is being submitted for inclusin in Ubunte due to the critical
> nature of the bug.
>
>
>
> == Fix ==
> https://lkml.org/lkml/2016/5/7/49:
>
> Commit-ID:  56402d63eefe22179f7311a51ff2094731420406
> Gitweb:     http://git.kernel.org/tip/56402d63eefe22179f7311a51ff2094731420406
> Author:     Thomas Gleixner <tglx at linutronix.de>
> AuthorDate: Fri, 6 May 2016 20:48:16 +0200
> Committer:  Thomas Gleixner <tglx at linutronix.de>
> CommitDate: Sat, 7 May 2016 10:06:55 +0200
>
> x86/topology: Handle CPUID bogosity gracefully
>
>
>
> == Test Case ==
> A test kernel was built with this patch and tested by multiple AWS users.
> It was reported that the test kernel resolved the bug.
>
>
> Thomas Gleixner (1):
>   x86/topology: Handle CPUID bogosity gracefully
>
>  arch/x86/kernel/smpboot.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
I should have also mentioned that this new patch is only needed in
Xenial and Yakkety.  It's needed in Xenial because commit 8ae10f463b
made it's way into Xenial via bug 1397880.  Yakkey will need this patch
once it is rebased to v4.6 because commit 8ae10f463b landed in mainline
as of 4.6-rc1.