Re: [v2] powerpc/book3s: mce: Move add_taint() later in virtual mode.

[Michael Ellerman <patch-notifications@ellerman.id.au>]

On Tue, 2017-04-18 at 16:38:17 UTC, Mahesh Salgaonkar wrote:
> From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
> 
> machine_check_early() gets called in real mode. The very first time when
> add_taint() is called, it prints a warning which ends up calling opal
> call (that uses OPAL_CALL wrapper) for writing it to console. If we get a
> very first machine check while we are in opal we are doomed. OPAL_CALL
> overwrites the PACASAVEDMSR in r13 and in this case when we are done with
> MCE handling the original opal call will use this new MSR on it's way
> back to opal_return. This usually leads unexpected behaviour or kernel
> to panic. Instead move the add_taint() call later in the virtual mode
> where it is safe to call.
> 
> This is broken with current FW level. We got lucky so far for not getting
> very first MCE hit while in OPAL. But easily reproducible on Mambo.
> This should go to stable.
> 
> Fixes: 27ea2c420cad powerpc: Set the correct kernel taint on machine check errors.
> Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/d93b0ac01a9ce276ec39644be47001

cheers