Re: [PATCH v13 4/7] arm64: mte: Enable TCO in functions that can read beyond buffer limits

diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 706b7ab75f31..65ecb86dd886 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c

@@ -26,6 +26,10 @@ u64 gcr_kernel_excl __ro_after_init;
 
 static bool report_fault_once = true;
 
+/* Whether the MTE asynchronous mode is enabled. */
+DEFINE_STATIC_KEY_FALSE(mte_async_mode);
+EXPORT_SYMBOL_GPL(mte_async_mode);
+
 static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap)
 {
 	pte_t old_pte = READ_ONCE(*ptep);

@@ -119,12 +123,24 @@ static inline void __mte_enable_kernel(const char *mode, unsigned long tcf)
 void mte_enable_kernel_sync(void)
 {
 	__mte_enable_kernel("synchronous", SCTLR_ELx_TCF_SYNC);
+
+	/*
+	 * This function is called on each active smp core at boot
+	 * time, hence we do not need to take cpu_hotplug_lock again.
+	 */
+	static_branch_disable_cpuslocked(&mte_async_mode);
 }
 EXPORT_SYMBOL_GPL(mte_enable_kernel_sync);
 
 void mte_enable_kernel_async(void)
 {
 	__mte_enable_kernel("asynchronous", SCTLR_ELx_TCF_ASYNC);
+
+	/*
+	 * This function is called on each active smp core at boot
+	 * time, hence we do not need to take cpu_hotplug_lock again.
+	 */
+	static_branch_enable_cpuslocked(&mte_async_mode);
 }