arm64: Branch predictor hardening for Cavium ThunderX2

Use PSCI based mitigation for speculative execution attacks targeting
the branch predictor. We use the same mechanism as the one used for
Cortex-A CPUs, we expect the PSCI version call to have a side effect
of clearing the BTBs.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jayachandran C <jnair@caviumnetworks.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/cpu_errata.c

@@ -359,6 +359,16 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		.capability = ARM64_HARDEN_BP_POST_GUEST_EXIT,
 		MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1),
 	},
+	{
+		.capability = ARM64_HARDEN_BRANCH_PREDICTOR,
+		MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
+		.enable = enable_psci_bp_hardening,
+	},
+	{
+		.capability = ARM64_HARDEN_BRANCH_PREDICTOR,
+		MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
+		.enable = enable_psci_bp_hardening,
+	},
 #endif
 	{
 	}