powerpc/64: Sanitise user registers on interrupt in pseries, POWERNV

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.

Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221201071019.1953023-7-rmclure@linux.ibm.com

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index aec1431..e21d6de 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -537,7 +537,7 @@ 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