ARM: KVM: invalidate BTB on guest exit for Cortex-A12/A17
Commit 3f7e8e2e1ebda787f156ce46e3f0a9ce2833fa4f upstream.
In order to avoid aliasing attacks against the branch predictor,
let's invalidate the BTB on guest exit. This is made complicated
by the fact that we cannot take a branch before invalidating the
BTB.
We only apply this to A12 and A17, which are the only two ARM
cores on which this useful.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Boot-tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: David A. Long <dave.long@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index e2f05ce..625edef 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -248,7 +248,22 @@
static inline void *kvm_get_hyp_vector(void)
{
- return kvm_ksym_ref(__kvm_hyp_vector);
+ switch(read_cpuid_part()) {
+#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
+ case ARM_CPU_PART_CORTEX_A12:
+ case ARM_CPU_PART_CORTEX_A17:
+ {
+ extern char __kvm_hyp_vector_bp_inv[];
+ return kvm_ksym_ref(__kvm_hyp_vector_bp_inv);
+ }
+
+#endif
+ default:
+ {
+ extern char __kvm_hyp_vector[];
+ return kvm_ksym_ref(__kvm_hyp_vector);
+ }
+ }
}
static inline int kvm_map_vectors(void)