0021-KVM-arm64-Add-interface-to-support-PV-qspinlock.patch

From e0e185e36ea8a9641dd4e5e410b49c423b0b93a0 Mon Sep 17 00:00:00 2001
From: AltArch Kernel <noreply@centos.org>
Date: Wed, 23 Sep 2020 16:56:12 +0800
Subject: [PATCH 21/25] KVM: arm64: Add interface to support  PV qspinlock

euleros inclusion
category: feature
bugzilla: NA
DTS: #231
CVE: NA

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

As kernel has used this interface, so lets support it.
---
 arch/arm64/Kconfig                          | 14 ++++++++++++++
 arch/arm64/include/asm/paravirt.h           | 29 +++++++++++++++++++++++++++++
 arch/arm64/include/asm/qspinlock.h          | 14 +++++++++++---
 arch/arm64/include/asm/qspinlock_paravirt.h | 12 ++++++++++++
 arch/arm64/include/asm/spinlock.h           |  3 +++
 arch/arm64/kernel/Makefile                  |  1 +
 arch/arm64/kernel/alternative.c             |  1 +
 arch/arm64/kernel/paravirt-spinlocks.c      |  5 +++++
 arch/arm64/kernel/paravirt.c                |  4 ++++
 9 files changed, 80 insertions(+), 3 deletions(-)
 create mode 100644 arch/arm64/include/asm/qspinlock_paravirt.h

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e2b6212..5810e1c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -698,6 +698,7 @@ config NODES_SHIFT
 config NUMA_AWARE_SPINLOCKS
 	bool "Numa-aware spinlocks"
 	depends on NUMA && QUEUED_SPINLOCKS
+	depends on PARAVIRT_SPINLOCKS
 	default n
 	help
 	  Introduce NUMA (Non Uniform Memory Access) awareness into
@@ -782,6 +783,19 @@ config PARAVIRT
 	  under a hypervisor, potentially improving performance significantly
 	  over full virtualization.
 
+config PARAVIRT_SPINLOCKS
+	bool "Paravirtualization layer for spinlocks"
+	depends on PARAVIRT && SMP
+	help
+	  Paravirtualized spinlocks allow a pvops backend to replace the
+	  spinlock implementation with something virtualization-friendly
+	  (for example, block the virtual CPU rather than spinning).
+
+	  It has a minimal impact on native kernels and gives a nice performance
+	  benefit on paravirtualized KVM kernels.
+
+	  If you are unsure how to answer this question, answer Y.
+
 config PARAVIRT_TIME_ACCOUNTING
 	bool "Paravirtual steal time accounting"
 	select PARAVIRT
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
index 62e9ba7..256e3f9 100644
--- a/arch/arm64/include/asm/paravirt.h
+++ b/arch/arm64/include/asm/paravirt.h
@@ -12,6 +12,12 @@ struct pv_time_ops {
 };
 
 struct pv_sched_ops {
+	void (*queued_spin_lock_slowpath)(struct qspinlock *lock, u32 val);
+	void (*queued_spin_unlock)(struct qspinlock *lock);
+
+	void (*wait)(u8 *ptr, u8 val);
+	void (*kick)(int cpu);
+
 	bool (*vcpu_is_preempted)(int cpu);
 };
 
@@ -35,6 +41,29 @@ static inline bool pv_vcpu_is_preempted(int cpu)
 	return pv_ops.sched.vcpu_is_preempted(cpu);
 }
 
+#if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT_SPINLOCKS)
+bool pv_is_native_spin_unlock(void);
+static inline void pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
+{
+	return pv_ops.sched.queued_spin_lock_slowpath(lock, val);
+}
+
+static inline void pv_queued_spin_unlock(struct qspinlock *lock)
+{
+	return pv_ops.sched.queued_spin_unlock(lock);
+}
+
+static inline void pv_wait(u8 *ptr, u8 val)
+{
+	return pv_ops.sched.wait(ptr, val);
+}
+
+static inline void pv_kick(int cpu)
+{
+	return pv_ops.sched.kick(cpu);
+}
+#endif /* SMP && PARAVIRT_SPINLOCKS */
+
 #else
 
 #define pv_sched_init() do {} while (0)
diff --git a/arch/arm64/include/asm/qspinlock.h b/arch/arm64/include/asm/qspinlock.h
index 1d35bc7..23aff07 100644
--- a/arch/arm64/include/asm/qspinlock.h
+++ b/arch/arm64/include/asm/qspinlock.h
@@ -2,11 +2,19 @@
 #ifndef _ASM_ARM64_QSPINLOCK_H
 #define _ASM_ARM64_QSPINLOCK_H
 
-#ifdef CONFIG_NUMA_AWARE_SPINLOCKS
 #include <asm-generic/qspinlock_types.h>
+#include <asm/paravirt.h>
+
+#define _Q_PENDING_LOOPS   (1 << 9)
 
+#ifdef CONFIG_NUMA_AWARE_SPINLOCKS
 extern void __cna_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
+#endif
+
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
 extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
+extern void __pv_init_lock_hash(void);
+extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
 
 #define	queued_spin_unlock queued_spin_unlock
 /**
@@ -22,12 +30,12 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock)
 
 static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
 {
-	__cna_queued_spin_lock_slowpath(lock, val);
+	pv_queued_spin_lock_slowpath(lock, val);
 }
 
 static inline void queued_spin_unlock(struct qspinlock *lock)
 {
-	native_queued_spin_unlock(lock);
+	pv_queued_spin_unlock(lock);
 }
 #endif
 
diff --git a/arch/arm64/include/asm/qspinlock_paravirt.h b/arch/arm64/include/asm/qspinlock_paravirt.h
new file mode 100644
index 0000000..eba4be2
--- /dev/null
+++ b/arch/arm64/include/asm/qspinlock_paravirt.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ */
+
+#ifndef __ASM_QSPINLOCK_PARAVIRT_H
+#define __ASM_QSPINLOCK_PARAVIRT_H
+
+extern void __pv_queued_spin_unlock(struct qspinlock *lock);
+
+#endif
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index 6e8db57..4fb3eda 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -27,6 +27,9 @@
 #define arch_read_relax(lock)	cpu_relax()
 #define arch_write_relax(lock)	cpu_relax()
 
+/* How long a lock should spin before we consider blocking */
+#define SPIN_THRESHOLD			(1 << 15)
+
 /* See include/linux/spinlock.h */
 #define smp_mb__after_spinlock()	smp_mb()
 
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index e1a562a..661b070 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -47,6 +47,7 @@ arm64-obj-$(CONFIG_ACPI)		+= acpi.o
 arm64-obj-$(CONFIG_ACPI_NUMA)		+= acpi_numa.o
 arm64-obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL)	+= acpi_parking_protocol.o
 arm64-obj-$(CONFIG_PARAVIRT)		+= paravirt.o paravirt-spinlocks.o
+arm64-obj-$(CONFIG_PARAVIRT_SPINLOCKS)	+= paravirt.o paravirt-spinlocks.o
 arm64-obj-$(CONFIG_RANDOMIZE_BASE)	+= kaslr.o
 arm64-obj-$(CONFIG_HIBERNATION)		+= hibernate.o hibernate-asm.o
 arm64-obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o	\
diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index 5c4bce4..d2a019b 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -26,6 +26,7 @@
 #include <asm/cpufeature.h>
 #include <asm/insn.h>
 #include <asm/sections.h>
+#include <asm/paravirt.h>
 #include <linux/stop_machine.h>
 
 #define __ALT_PTR(a,f)		((void *)&(a)->f + (a)->f)
diff --git a/arch/arm64/kernel/paravirt-spinlocks.c b/arch/arm64/kernel/paravirt-spinlocks.c
index fd733eb..3cb43f9 100644
--- a/arch/arm64/kernel/paravirt-spinlocks.c
+++ b/arch/arm64/kernel/paravirt-spinlocks.c
@@ -11,3 +11,8 @@ __visible bool __native_vcpu_is_preempted(int cpu)
 {
 	return false;
 }
+
+bool pv_is_native_spin_unlock(void)
+{
+	return false;
+}
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index 2370908..3edbcf8 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -30,6 +30,10 @@
 struct static_key paravirt_steal_rq_enabled;
 
 struct paravirt_patch_template pv_ops = {
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+	.sched.queued_spin_lock_slowpath	= native_queued_spin_lock_slowpath,
+	.sched.queued_spin_unlock		= native_queued_spin_unlock,
+#endif
 	.sched.vcpu_is_preempted		= __native_vcpu_is_preempted,
 };
 EXPORT_SYMBOL_GPL(pv_ops);
-- 
1.8.3.1