[PATCH v3 7/8] KVM: arm64: Add interface to support vCPU preempted check
From: Zengruan Ye <hidden>
Date: 2020-01-16 12:47:08
Also in:
kvm, kvmarm, linux-arm-kernel, linux-doc, lkml
Subsystem:
arm64 port (aarch64 architecture), locking primitives, paravirt_ops interface, the rest · Maintainers:
Catalin Marinas, Will Deacon, Peter Zijlstra, Ingo Molnar, Boqun Feng, Juergen Gross, Linus Torvalds
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. Reported-by: kbuild test robot <redacted> Signed-off-by: Zengruan Ye <redacted> --- arch/arm64/include/asm/paravirt.h | 12 ++++++++++++ arch/arm64/include/asm/spinlock.h | 9 +++++++++ arch/arm64/kernel/Makefile | 2 +- arch/arm64/kernel/paravirt-spinlocks.c | 13 +++++++++++++ arch/arm64/kernel/paravirt.c | 4 +++- 5 files changed, 38 insertions(+), 2 deletions(-) create mode 100644 arch/arm64/kernel/paravirt-spinlocks.c
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
index cf3a0fd7c1a7..7b1c81b544bb 100644
--- a/arch/arm64/include/asm/paravirt.h
+++ b/arch/arm64/include/asm/paravirt.h@@ -11,8 +11,13 @@ struct pv_time_ops { unsigned long long (*steal_clock)(int cpu); }; +struct pv_lock_ops { + bool (*vcpu_is_preempted)(int cpu); +}; + struct paravirt_patch_template { struct pv_time_ops time; + struct pv_lock_ops lock; }; extern struct paravirt_patch_template pv_ops;
@@ -24,6 +29,13 @@ 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.lock.vcpu_is_preempted(cpu); +} + #else #define pv_time_init() do {} while (0)
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index b093b287babf..b5d1982414c5 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h@@ -7,8 +7,17 @@ #include <asm/qrwlock.h> #include <asm/qspinlock.h> +#include <asm/paravirt.h> /* See include/linux/spinlock.h */ #define smp_mb__after_spinlock() smp_mb() +#ifdef CONFIG_PARAVIRT +#define vcpu_is_preempted vcpu_is_preempted +static inline bool vcpu_is_preempted(long cpu) +{ + return pv_vcpu_is_preempted(cpu); +} +#endif // CONFIG_PARAVIRT + #endif /* __ASM_SPINLOCK_H */
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index fc6488660f64..b23cdae433a4 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile@@ -50,7 +50,7 @@ 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 \
diff --git a/arch/arm64/kernel/paravirt-spinlocks.c b/arch/arm64/kernel/paravirt-spinlocks.c
new file mode 100644
index 000000000000..718aa773d45c
--- /dev/null
+++ b/arch/arm64/kernel/paravirt-spinlocks.c@@ -0,0 +1,13 @@ +/* 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; +}
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index 1ef702b0be2d..d8f1ba8c22ce 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/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 = { + .lock.vcpu_is_preempted = __native_vcpu_is_preempted, +}; EXPORT_SYMBOL_GPL(pv_ops); struct pv_time_stolen_time_region {
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2.19.1