Patch "[Variant 2/Spectre-v2] arm64: Run enable method for errata work arounds on late CPUs" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

[Variant 2/Spectre-v2] arm64: Run enable method for errata work arounds on late CPUs

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm64-run-enable-method-for-errata-work-arounds-on-late-cpus.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Suzuki K Poulose <[email protected]>
Date: Wed, 17 Jan 2018 17:42:20 +0000
Subject: [Variant 2/Spectre-v2] arm64: Run enable method for errata work arounds on late CPUs

From: Suzuki K Poulose <[email protected]>

Commit 55b35d070c25 upstream.

When a CPU is brought up after we have finalised the system wide capabilities (i.e, features and errata), we make sure the new CPU doesn't need a new errata work around which has not been detected already. However we don't run enable() method on the new CPU for the errata work arounds already detected. This could cause the new CPU running without potential work arounds. It is upto the "enable()" method to decide if this CPU should do something about the errata.

---
 arch/arm64/kernel/cpu_errata.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

@@ -221,15 +221,18 @@ void verify_local_cpu_errata_workarounds
 {
 	const struct arm64_cpu_capabilities *caps = arm64_errata;
 
-	for (; caps->matches; caps++)
-		if (!cpus_have_cap(caps->capability) &&
-			caps->matches(caps, SCOPE_LOCAL_CPU)) {
+	for (; caps->matches; caps++) {
+		if (cpus_have_cap(caps->capability)) {
+			if (caps->enable)
+				caps->enable((void *)caps);
+		} else if (caps->matches(caps, SCOPE_LOCAL_CPU)) {
 			pr_crit("CPU%d: Requires work around for %s, not detected"
 					" at boot time\n",
 				smp_processor_id(),
 				caps->desc ? : "an erratum");
 			cpu_die_early();
 		}
+	}
 }
 
 void update_cpu_errata_workarounds(void)

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/arm64-cpufeature-pass-capability-structure-to-enable-callback.patch queue-4.15/arm64-capabilities-handle-duplicate-entries-for-a-capability.patch queue-4.15/arm64-take-into-account-id_aa64pfr0_el1.csv3.patch queue-4.15/arm64-run-enable-method-for-errata-work-arounds-on-late-cpus.patch queue-4.15/arm64-cpufeature-__this_cpu_has_cap-shouldn-t-stop-early.patch