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

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Message-ID: <183e9acb-4562-af7c-a50b-52cee5954d9e@linux.ibm.com>
Date:   Tue, 9 Jun 2020 14:25:49 +0200
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Ram Pai <linuxram@...ibm.com>,
        Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Subject: Re: [PATCH] powerpc/pseries/svm: Remove unwanted check for
 shared_lppaca_size

Le 09/06/2020 à 12:57, Satheesh Rajendran a écrit :
> 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.
> 

Reviewed-by: Laurent Dufour <ldufour@...ux.ibm.com>

> 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(-)
> 
> diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
> index 949eceb25..10b7c54a7 100644
> --- a/arch/powerpc/kernel/paca.c
> +++ b/arch/powerpc/kernel/paca.c
> @@ -86,7 +86,7 @@ static void *__init alloc_shared_lppaca(unsigned long size, unsigned long align,
>   	 * This is very early in boot, so no harm done if the kernel crashes at
>   	 * this point.
>   	 */
> -	BUG_ON(shared_lppaca_size >= shared_lppaca_total_size);
> +	BUG_ON(shared_lppaca_size > shared_lppaca_total_size);
>   
>   	return ptr;
>   }
>