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: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200721094445.82184-3-dbrazdil@google.com
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 31380da..152deef 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1182,22 +1182,6 @@
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
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 68140fd..bd12011e 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -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);
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index ad06d68..a524142 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -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,
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 13489af..318c8f2 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -58,7 +58,7 @@
virtual machines.
config KVM_INDIRECT_VECTORS
- def_bool HARDEN_BRANCH_PREDICTOR || HARDEN_EL2_VECTORS
+ def_bool HARDEN_BRANCH_PREDICTOR || RANDOMIZE_BASE
endif # KVM