From: Marc Zyngier maz@kernel.org

Commit 73f381660959 ("arm64: Advertise mitigation of Spectre-v2, or lack thereof") changed the way we deal with ARCH_WORKAROUND_1, by moving most of the enabling code to the .matches() callback.

This has the unfortunate effect that the workaround gets only enabled on the first affected CPU, and no other.

In order to address this, forcefully call the .matches() callback from a .cpu_enable() callback, which brings us back to the original behaviour.

Fixes: 73f381660959 ("arm64: Advertise mitigation of Spectre-v2, or lack thereof") Cc: stable@vger.kernel.org Reviewed-by: Suzuki K Poulose suzuki.poulose@arm.com Signed-off-by: Marc Zyngier maz@kernel.org Signed-off-by: Will Deacon will@kernel.org --- arch/arm64/kernel/cpu_errata.c | 8 ++++++++ 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 88966496806a..3fe64bf5a58d 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -599,6 +599,12 @@ check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope) return (need_wa > 0); }

+static void +cpu_enable_branch_predictor_hardening(const struct arm64_cpu_capabilities *cap) +{ + cap->matches(cap, SCOPE_LOCAL_CPU); +} + static const __maybe_unused struct midr_range tx2_family_cpus[] = { MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN), MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2), @@ -890,9 +896,11 @@ const struct arm64_cpu_capabilities arm64_errata[] = { }, #endif { + .desc = "Branch predictor hardening", .capability = ARM64_HARDEN_BRANCH_PREDICTOR, .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, .matches = check_branch_predictor, + .cpu_enable = cpu_enable_branch_predictor_hardening, }, #ifdef CONFIG_RANDOMIZE_BASE {