linux-kernel - Re: [PATCH] powerpc/pseries/svm: Remove unwanted check for shared_lppaca

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Date:   Wed, 10 Jun 2020 01:15:21 -0300
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Ram Pai <linuxram@...ibm.com>,
        Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
        Laurent Dufour <ldufour@...ux.ibm.com>
Subject: Re: [PATCH] powerpc/pseries/svm: Remove unwanted check for shared_lppaca_size


Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com> writes:

> Early secure guest boot hits the below crash while booting with
> vcpus numbers aligned with page boundary for PAGE size of 64k
> and LPPACA size of 1k i.e 64, 128 etc, due to the BUG_ON assert
> for shared_lppaca_total_size equal to shared_lppaca_size,
>
>  [    0.000000] Partition configured for 64 cpus.
>  [    0.000000] CPU maps initialized for 1 thread per core
>  [    0.000000] ------------[ cut here ]------------
>  [    0.000000] kernel BUG at arch/powerpc/kernel/paca.c:89!
>  [    0.000000] Oops: Exception in kernel mode, sig: 5 [#1]
>  [    0.000000] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
>
> which is not necessary, let's remove it.
>
> Cc: linux-kernel@...r.kernel.org
> Cc: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
> Cc: Ram Pai <linuxram@...ibm.com>
> Cc: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
> Cc: Laurent Dufour <ldufour@...ux.ibm.com>
> Signed-off-by: Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>
> ---
>  arch/powerpc/kernel/paca.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Thanks for fixing this bug! I would only add:

Fixes: bd104e6db6f0 ("powerpc/pseries/svm: Use shared memory for LPPACA structures")

In any case:

Reviewed-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>

-- 
Thiago Jung Bauermann
IBM Linux Technology Center