euleros inclusion category: feature bugzilla: NA DTS: NA CVE: NA
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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: Zengruan Ye yezengruan@huawei.com --- arch/arm64/include/asm/paravirt.h | 12 ++++++++++++ arch/arm64/include/asm/spinlock.h | 10 ++++++++++ arch/arm64/kernel/Makefile | 2 +- arch/arm64/kernel/paravirt-spinlocks.c | 13 +++++++++++++ arch/arm64/kernel/paravirt.c | 4 +++- 5 files changed, 39 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 799d9dd6f..ff266c66c 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_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; @@ -21,6 +26,13 @@ static inline u64 paravirt_steal_clock(int cpu) { return pv_ops.time.steal_clock(cpu); } + +__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); +} + #endif
#endif diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h index a9dec081b..4a6689950 100644 --- a/arch/arm64/include/asm/spinlock.h +++ b/arch/arm64/include/asm/spinlock.h @@ -18,6 +18,7 @@
#include <asm/qrwlock.h> #include <asm/qspinlock.h> +#include <asm/paravirt.h>
/* See include/linux/spinlock.h */ #define smp_mb__after_spinlock() smp_mb() @@ -30,9 +31,18 @@ * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-a... */ #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 */ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 54d0b1d38..73bc1db45 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -48,7 +48,7 @@ arm64-obj-$(CONFIG_ACPI) += acpi.o arm64-obj-$(CONFIG_ARM64_ERR_RECOV) += ras.o arm64-obj-$(CONFIG_ACPI_NUMA) += acpi_numa.o arm64-obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL) += acpi_parking_protocol.o -arm64-obj-$(CONFIG_PARAVIRT) += paravirt.o +arm64-obj-$(CONFIG_PARAVIRT) += 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/paravirt-spinlocks.c b/arch/arm64/kernel/paravirt-spinlocks.c new file mode 100644 index 000000000..fd733eb02 --- /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 75c158b03..3a410dbaa 100644 --- a/arch/arm64/kernel/paravirt.c +++ b/arch/arm64/kernel/paravirt.c @@ -21,5 +21,7 @@ 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);