From dee39247dc75465a24990cb1772c6aaced5fd910 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 15 Feb 2018 11:47:14 +0000 Subject: arm64: KVM: Allow mapping of vectors outside of the RAM region We're now ready to map our vectors in weird and wonderful locations. On enabling ARM64_HARDEN_EL2_VECTORS, a vector slot gets allocated if this hasn't been already done via ARM64_HARDEN_BRANCH_PREDICTOR and gets mapped outside of the normal RAM region, next to the idmap. That way, being able to obtain VBAR_EL2 doesn't reveal the mapping of the rest of the hypervisor code. Acked-by: Catalin Marinas Signed-off-by: Marc Zyngier --- arch/arm64/Kconfig | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/arm64/Kconfig') diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 7381eeb7ef8e..48ad7ca23f39 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -904,6 +904,22 @@ config HARDEN_BRANCH_PREDICTOR If unsure, say Y. +config HARDEN_EL2_VECTORS + bool "Harden EL2 vector mapping against system register leak" if EXPERT + default y + help + Speculation attacks against some high-performance processors can + be used to leak privileged information such as the vector base + register, resulting in a potential defeat of the EL2 layout + randomization. + + This config option will map the vectors to a fixed location, + independent of the EL2 code mapping, so that revealing VBAR_EL2 + to an attacker does not give away any extra information. This + only gets enabled on affected CPUs. + + If unsure, say Y. + menuconfig ARMV8_DEPRECATED bool "Emulate deprecated/obsolete ARMv8 instructions" depends on COMPAT -- cgit v1.2.3