Re: [PATCH v6 12/17] KVM: arm64: Add PROTECTED_NVHE_STACKTRACE Kconfig

[Marc Zyngier]

On Tue, 26 Jul 2022 08:37:45 +0100,
Kalesh Singh <kaleshsingh@xxxxxxxxxx> wrote:
> 
> This can be used to disable stacktrace for the protected KVM
> nVHE hypervisor, in order to save on the associated memory usage.
> 
> This option is disabled by default, since protected KVM is not widely
> used on platforms other than Android currently.
> 
> Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
> Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>
> Tested-by: Fuad Tabba <tabba@xxxxxxxxxx>
> ---
> 
> Changes in v6:
>   - Add Fuad’s Reviewed-by and Tested-by tags
> 
> Changes in v5:
>   - Make PROTECTED_NVHE_STACKTRACE depend on NVHE_EL2_DEBUG, per Marc
> 
>  arch/arm64/kvm/Kconfig | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 8a5fbbf084df..09c995869916 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -46,6 +46,21 @@ menuconfig KVM
>  
>  	  If unsure, say N.
>  
> +config PROTECTED_NVHE_STACKTRACE
> +	bool "Protected KVM hypervisor stacktraces"
> +	depends on NVHE_EL2_DEBUG
> +	default n
> +	help
> +	  Say Y here to enable pKVM hypervisor stacktraces on hyp_panic()
> +
> +	  If you are not using protected nVHE (pKVM), say N.
> +
> +	  If using protected nVHE mode, but cannot afford the associated
> +	  memory cost (less than 0.75 page per CPU) of pKVM stacktraces,
> +	  say N.
> +
> +	  If unsure, say N.
> +
>  config NVHE_EL2_DEBUG
>  	bool "Debug mode for non-VHE EL2 object"
>  	depends on KVM

Having NVHE_EL2_DEBUG after PROTECTED_NVHE_STACKTRACE is pretty odd
when you use 'make menuconfig', as the new option appears out of
sequence.

I'll move it around, no need to respin for this.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.