Re: [PATCH] powerpc: fix dead default for GUEST_STATE_BUFFER_TEST

[Amit Machhiwal <amachhiw@linux.ibm.com>]

Hi Julian,

Thanks for the patch.

On 2026/04/05 05:15 PM, Julian Braha wrote:
> The GUEST_STATE_BUFFER_TEST config option should default
> to KUNIT_ALL_TESTS so that if all tests are enabled then
> it is included, but currently the 'default KUNIT_ALL_TESTS'
> statement is shadowed by 'def_tristate n',
> meaning that this second default statement is currently dead code.
> 
> It looks to me like the commit
> 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
> intended to set the default to KUNIT_ALL_TESTS, but mistakenly
> missed the def_tristate.
> 
> This dead code was found by kconfirm, a static analysis tool for Kconfig.
> 
> Fixes: 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
> Signed-off-by: Julian Braha <julianbraha@gmail.com>
> ---
>  arch/powerpc/Kconfig.debug | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)

This test is specific to KVM nested API v2 and is currently opt-in only.
This patch enables it by default when KUNIT_ALL_TESTS=y.

Since PPC kernels in general are built for both PowerNV and pSeries
platforms, and the API v2 code is always compiled in. Also, the tests
operate on guest state buffer in memory and no hcalls are involved,
enabling the test by default makes sense. Hence:

Reviewed-by: Amit Machhiwal <amachhiw@linux.ibm.com>

Thanks,
Amit

> 
> diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
> index f15e5920080b..e8718bc13eeb 100644
> --- a/arch/powerpc/Kconfig.debug
> +++ b/arch/powerpc/Kconfig.debug
> @@ -83,11 +83,10 @@ config MSI_BITMAP_SELFTEST
>  	depends on DEBUG_KERNEL
>  
>  config GUEST_STATE_BUFFER_TEST
> -	def_tristate n
> +	def_tristate KUNIT_ALL_TESTS
>  	prompt "Enable Guest State Buffer unit tests"
>  	depends on KUNIT
>  	depends on KVM_BOOK3S_HV_POSSIBLE
> -	default KUNIT_ALL_TESTS
>  	help
>  	  The Guest State Buffer is a data format specified in the PAPR.
>  	  It is by hcalls to communicate the state of L2 guests between
> -- 
> 2.53.0
>