[PATCH 4/4] powerpc/64s: Sanitise user registers on interrupt in pseries

[Rohan McLure <rmclure@linux.ibm.com>]

Cause pseries 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. Interrupt sources include syscalls.

Signed-off-by: Rohan McLure <rmclure@linux.ibm.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/
Standalone series: new patch
---
 arch/powerpc/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9d3d20c6f365..2eb328b25e49 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -532,7 +532,7 @@ 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
 	help
 	  Reduce the influence of user register state on interrupt handlers and
 	  syscalls through clearing user state from registers before handling
-- 
2.34.1