The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 18fce56134c987e5b4eceddafdbe4b00c07e2ae1 Mon Sep 17 00:00:00 2001

From: Marc Zyngier maz@kernel.org Date: Thu, 16 Jul 2020 17:11:09 +0100 Subject: [PATCH] arm64: Run ARCH_WORKAROUND_1 enabling code on all CPUs

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

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 {