locking/qspinlock: Add CNA support for ARM64

hulk inclusion
category: feature
bugzilla: 169576
CVE: NA

-------------------------------------------------

Enabling CNA is controlled via a new configuration option
(NUMA_AWARE_SPINLOCKS). Add it for arm64.
Signed-off-by: NWei Li <liwei391@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/Kconfig

@@ -1075,6 +1075,22 @@ config NODES_SHIFT
 	  Specify the maximum number of NUMA Nodes available on the target
 	  system.  Increases memory reserved to accommodate various tables.
 
+config NUMA_AWARE_SPINLOCKS
+	bool "Numa-aware spinlocks"
+	depends on NUMA
+	depends on QUEUED_SPINLOCKS
+	depends on PARAVIRT_SPINLOCKS
+	default y
+	help
+	  Introduce NUMA (Non Uniform Memory Access) awareness into
+	  the slow path of spinlocks.
+
+	  In this variant of qspinlock, the kernel will try to keep the lock
+	  on the same node, thus reducing the number of remote cache misses,
+	  while trading some of the short term fairness for better performance.
+
+	  Say N if you want absolute first come first serve fairness.
+
 config USE_PERCPU_NUMA_NODE_ID
 	def_bool y
 	depends on NUMA

arch/arm64/include/asm/qspinlock.h

@@ -14,6 +14,10 @@
 
 #define _Q_PENDING_LOOPS	(1 << 9)
 
+#ifdef CONFIG_NUMA_AWARE_SPINLOCKS
+extern void cna_configure_spin_lock_slowpath(void);
+#endif
+
 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
 extern void __pv_init_lock_hash(void);

arch/x86/kernel/alternative.c

@@ -741,10 +741,6 @@ void __init alternative_instructions(void)
 	}
 #endif
 
-#if defined(CONFIG_NUMA_AWARE_SPINLOCKS)
-	cna_configure_spin_lock_slowpath();
-#endif
-
 	apply_paravirt(__parainstructions, __parainstructions_end);
 
 	restart_nmi();

mm/mempolicy.c

@@ -2823,6 +2823,10 @@ void __init numa_policy_init(void)
 		pr_err("%s: interleaving failed\n", __func__);
 
 	check_numabalancing_enable();
+
+#if defined(CONFIG_NUMA_AWARE_SPINLOCKS)
+	cna_configure_spin_lock_slowpath();
+#endif
 }
 
 /* Reset policy of current process to default */