From 25fc42b6b09d0f4626f8766e29d32e95186d4414 Mon Sep 17 00:00:00 2001

From: Marc Zyngier <maz@kernel.org>

Date: Thu, 16 Jul 2020 17:11:09 +0100

Subject: [PATCH 5/6] arm64: Run ARCH_WORKAROUND_1 enabling code on all CPUs

Git-commit: 18fce56134c987e5b4eceddafdbe4b00c07e2ae1

Patch-mainline: v5.10-rc1

References: git-fixes

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>

Acked-by: Denis Kirjanov <denis.kirjanov@suse.com>

---

 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 8d2562f16e7f..858880c86c50 100644

--- a/arch/arm64/kernel/cpu_errata.c

+++ b/arch/arm64/kernel/cpu_errata.c

@@ -646,6 +646,12 @@ 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);

+}

+

 #ifdef CONFIG_CAVIUM_ERRATUM_27456

 const struct midr_range cavium_erratum_27456_cpus[] = {

 	/* Cavium ThunderX, T88 pass 1.x - 2.1 */

@@ -797,9 +803,11 @@ 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,

 	},

 	{

 		.desc = "Speculative Store Bypass Disable",

-- 

2.16.4