KVM: arm64: Add interface to support vCPU preempted check

virt inclusion
category: feature
bugzilla: 47624
CVE: NA

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

This is to fix some lock holder preemption issues. Some other locks
implementation do a spin loop before acquiring the lock itself.
Currently kernel has an interface of bool vcpu_is_preempted(int cpu). It
takes the CPU as parameter and return true if the CPU is preempted.
Then kernel can break the spin loops upon the retval of vcpu_is_preempted.

As kernel has used this interface, So lets support it.
Signed-off-by: NZengruan Ye <yezengruan@huawei.com>
Reviewed-by: NZhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/include/asm/paravirt.h

@@ -11,8 +11,13 @@ struct pv_time_ops {
 	unsigned long long (*steal_clock)(int cpu);
 };
 
+struct pv_sched_ops {
+	bool (*vcpu_is_preempted)(int cpu);
+};
+
 struct paravirt_patch_template {
 	struct pv_time_ops time;
+	struct pv_sched_ops sched;
 };
 
 extern struct paravirt_patch_template pv_ops;
@@ -24,6 +29,12 @@ static inline u64 paravirt_steal_clock(int cpu)
 
 int __init pv_time_init(void);
 
+__visible bool __native_vcpu_is_preempted(int cpu);
+static inline bool pv_vcpu_is_preempted(int cpu)
+{
+	return pv_ops.sched.vcpu_is_preempted(cpu);
+}
+
 #else
 
 #define pv_time_init() do {} while (0)

arch/arm64/include/asm/spinlock.h

@@ -7,6 +7,7 @@
 
 #include <asm/qrwlock.h>
 #include <asm/qspinlock.h>
+#include <asm/paravirt.h>
 
 /* See include/linux/spinlock.h */
 #define smp_mb__after_spinlock()	smp_mb()
@@ -19,9 +20,18 @@
  * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
  */
 #define vcpu_is_preempted vcpu_is_preempted
+#ifdef CONFIG_PARAVIRT
+static inline bool vcpu_is_preempted(int cpu)
+{
+	return pv_vcpu_is_preempted(cpu);
+}
+
+#else
+
 static inline bool vcpu_is_preempted(int cpu)
 {
 	return false;
 }
+#endif /* CONFIG_PARAVIRT */
 
 #endif /* __ASM_SPINLOCK_H */

arch/arm64/kernel/Makefile

@@ -49,7 +49,7 @@ obj-$(CONFIG_ARMV8_DEPRECATED)		+= armv8_deprecated.o
 obj-$(CONFIG_ACPI)			+= acpi.o
 obj-$(CONFIG_ACPI_NUMA)			+= acpi_numa.o
 obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL)	+= acpi_parking_protocol.o
-obj-$(CONFIG_PARAVIRT)			+= paravirt.o
+obj-$(CONFIG_PARAVIRT)			+= paravirt.o paravirt-spinlocks.o
 obj-$(CONFIG_RANDOMIZE_BASE)		+= kaslr.o
 obj-$(CONFIG_HIBERNATION)		+= hibernate.o hibernate-asm.o
 obj-$(CONFIG_KEXEC_CORE)		+= machine_kexec.o relocate_kernel.o	\

arch/arm64/kernel/paravirt-spinlocks.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ */
+
+#include <linux/spinlock.h>
+#include <asm/paravirt.h>
+
+__visible bool __native_vcpu_is_preempted(int cpu)
+{
+	return false;
+}

arch/arm64/kernel/paravirt.c

@@ -26,7 +26,9 @@
 struct static_key paravirt_steal_enabled;
 struct static_key paravirt_steal_rq_enabled;
 
-struct paravirt_patch_template pv_ops;
+struct paravirt_patch_template pv_ops = {
+	.sched.vcpu_is_preempted		= __native_vcpu_is_preempted,
+};
 EXPORT_SYMBOL_GPL(pv_ops);
 
 struct pv_time_stolen_time_region {