Commit a59a2edb authored by David Brazdil's avatar David Brazdil Committed by Marc Zyngier
Browse files

KVM: arm64: Substitute RANDOMIZE_BASE for HARDEN_EL2_VECTORS 



The HARDEN_EL2_VECTORS config maps vectors at a fixed location on cores which
are susceptible to Spector variant 3a (A57, A72) to prevent defeating hyp
layout randomization by leaking the value of VBAR_EL2.

Since this feature is only applicable when EL2 layout randomization is enabled,
unify both behind the same RANDOMIZE_BASE Kconfig. Majority of code remains
conditional on a capability selected for the affected cores.

Signed-off-by: default avatarDavid Brazdil <dbrazdil@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200721094445.82184-3-dbrazdil@google.com
parent 24f69c0f

arch/arm64/Kconfig

+0 −16
Original line number Diff line number Diff line
@@ -1182,22 +1182,6 @@ 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.



config ARM64_SSBD

	bool "Speculative Store Bypass Disable" if EXPERT

	default y

arch/arm64/include/asm/mmu.h

+2 −4
Original line number Diff line number Diff line
@@ -42,12 +42,10 @@ struct bp_hardening_data { 
	bp_hardening_cb_t	fn;

};



#if (defined(CONFIG_HARDEN_BRANCH_PREDICTOR) ||	\

     defined(CONFIG_HARDEN_EL2_VECTORS))



#ifdef CONFIG_KVM_INDIRECT_VECTORS

extern char __bp_harden_hyp_vecs[];

extern atomic_t arm64_el2_vector_last_slot;

#endif  /* CONFIG_HARDEN_BRANCH_PREDICTOR || CONFIG_HARDEN_EL2_VECTORS */

#endif



#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR

DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);

arch/arm64/kernel/cpu_errata.c

+2 −2
Original line number Diff line number Diff line
@@ -635,7 +635,7 @@ has_neoverse_n1_erratum_1542419(const struct arm64_cpu_capabilities *entry, 
	return is_midr_in_range(midr, &range) && has_dic;

}



#if defined(CONFIG_HARDEN_EL2_VECTORS)

#ifdef CONFIG_RANDOMIZE_BASE



static const struct midr_range ca57_a72[] = {

	MIDR_ALL_VERSIONS(MIDR_CORTEX_A57),
@@ -880,7 +880,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = { 
		.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,

		.matches = check_branch_predictor,

	},

#ifdef CONFIG_HARDEN_EL2_VECTORS

#ifdef CONFIG_RANDOMIZE_BASE

	{

		.desc = "EL2 vector hardening",

		.capability = ARM64_HARDEN_EL2_VECTORS,

arch/arm64/kvm/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ config KVM_ARM_PMU 
	  virtual machines.



config KVM_INDIRECT_VECTORS

	def_bool HARDEN_BRANCH_PREDICTOR || HARDEN_EL2_VECTORS

	def_bool HARDEN_BRANCH_PREDICTOR || RANDOMIZE_BASE



endif # KVM

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