[PATCH v4 7/7] powerpc/64: Sanitise user registers on interrupt in pseries, POWERNV

[Nicholas Piggin]

On Tue Nov 29, 2022 at 2:43 PM AEST, Rohan McLure wrote:
> Cause pseries and POWERNV platforms to default to zeroising all potentially
> user-defined registers when entering the kernel by means of any interrupt
> source, reducing user-influence of the kernel and the likelihood or
> producing speculation gadgets.
>
> Signed-off-by: Rohan McLure <rmclure at linux.ibm.com>
 
Acked-by: Nicholas Piggin <npiggin at gmail.com>

> ---
> Resubmitting patches as their own series after v6 partially merged:
> Link: https://lore.kernel.org/all/166488988686.779920.13794870102696416283.b4-ty@ellerman.id.au/t/
> v4: Default on POWERNV as well.
> ---
>  arch/powerpc/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 280c797e0f30..2ab114a02f62 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -534,7 +534,7 @@ config HOTPLUG_CPU
>  config INTERRUPT_SANITIZE_REGISTERS
>  	bool "Clear gprs on interrupt arrival"
>  	depends on PPC64 && ARCH_HAS_SYSCALL_WRAPPER
> -	default PPC_BOOK3E_64
> +	default PPC_BOOK3E_64 || PPC_PSERIES || PPC_POWERNV
>  	help
>  	  Reduce the influence of user register state on interrupt handlers and
>  	  syscalls through clearing user state from registers before handling
> -- 
> 2.37.2