diff mbox series

powerpc/pseries/svm: Remove unwanted check for shared_lppaca_size

Message ID 20200609105731.14032-1-sathnaga@linux.vnet.ibm.com (mailing list archive)
State Superseded
Headers show
Series powerpc/pseries/svm: Remove unwanted check for shared_lppaca_size | expand

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Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (ec7b8eb9bc7a519047485c95f7292b48f5b73fe6)
snowpatch_ozlabs/build-ppc64le success Build succeeded
snowpatch_ozlabs/build-ppc64be success Build succeeded
snowpatch_ozlabs/build-ppc64e success Build succeeded
snowpatch_ozlabs/build-pmac32 success Build succeeded
snowpatch_ozlabs/checkpatch warning total: 0 errors, 1 warnings, 0 checks, 8 lines checked
snowpatch_ozlabs/needsstable success Patch has no Fixes tags

Commit Message

Satheesh Rajendran June 9, 2020, 10:57 a.m. UTC
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@vger.kernel.org
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/paca.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Laurent Dufour June 9, 2020, 12:25 p.m. UTC | #1
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@linux.ibm.com>

> Cc: linux-kernel@vger.kernel.org
> Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
> Cc: Ram Pai <linuxram@us.ibm.com>
> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> Cc: Laurent Dufour <ldufour@linux.ibm.com>
> Signed-off-by: Satheesh Rajendran <sathnaga@linux.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;
>   }
>
Thiago Jung Bauermann June 10, 2020, 4:15 a.m. UTC | #2
Satheesh Rajendran <sathnaga@linux.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@vger.kernel.org
> Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
> Cc: Ram Pai <linuxram@us.ibm.com>
> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> Cc: Laurent Dufour <ldufour@linux.ibm.com>
> Signed-off-by: Satheesh Rajendran <sathnaga@linux.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@linux.ibm.com>
diff mbox series

Patch

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;
 }