From ad26870d2a02a2e49aa18dc7c48e09585a67cb8a Mon Sep 17 00:00:00 2001 From: Zengruan Ye Date: Thu, 22 Apr 2021 20:15:54 +0800 Subject: [PATCH] KVM: arm64: Support the vCPU preemption check euleros inclusion category: feature bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=35 CVE: NA -------------------------------- Support the vcpu_is_preempted() functionality under KVM/arm64. This will enhance lock performance on overcommitted hosts (more runnable vCPUs than physical CPUs in the system) as doing busy waits for preempted vCPUs will hurt system performance far worse than early yielding. unix benchmark result: host: kernel 4.19.87, HiSilicon Kunpeng920, 8 CPUs guest: kernel 4.19.87, 16 vCPUs test-case | after-patch | before-patch ----------------------------------------+-------------------+------------------ Dhrystone 2 using register variables | 338955728.5 lps | 339266319.5 lps Double-Precision Whetstone | 30634.9 MWIPS | 30884.4 MWIPS Execl Throughput | 6753.2 lps | 3580.1 lps File Copy 1024 bufsize 2000 maxblocks | 490048.0 KBps | 313282.3 KBps File Copy 256 bufsize 500 maxblocks | 129662.5 KBps | 83550.7 KBps File Copy 4096 bufsize 8000 maxblocks | 1552551.5 KBps | 814327.0 KBps Pipe Throughput | 8976422.5 lps | 9048628.4 lps Pipe-based Context Switching | 258641.7 lps | 252925.9 lps Process Creation | 5312.2 lps | 4507.9 lps Shell Scripts (1 concurrent) | 8704.2 lpm | 6720.9 lpm Shell Scripts (8 concurrent) | 1708.8 lpm | 607.2 lpm System Call Overhead | 3714444.7 lps | 3746386.8 lps ----------------------------------------+-------------------+------------------ System Benchmarks Index Score | 2270.6 | 1679.2 Signed-off-by: Zengruan Ye Reviewed-by: zhanghailiang Signed-off-by: Yang Yingliang Signed-off-by: Chaochao Xing Reviewed-by: Zengruan Ye Reviewed-by: Xiangyou Xie Signed-off-by: Cheng Jian --- arch/arm64/include/asm/paravirt.h | 8 ++- arch/arm64/kernel/paravirt.c | 112 ++++++++++++++++++++++++++++++ arch/arm64/kernel/setup.c | 2 + 3 files changed, 121 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h index 5c250cb9a52e..68b25d0eefe1 100644 --- a/arch/arm64/include/asm/paravirt.h +++ b/arch/arm64/include/asm/paravirt.h @@ -27,12 +27,18 @@ static inline u64 paravirt_steal_clock(int cpu) return pv_time_ops.steal_clock(cpu); } +int __init pv_sched_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); } -#endif +#else + +#define pv_sched_init() do {} while (0) + +#endif /* CONFIG_PARAVIRT */ #endif diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c index d5ce2d362e6e..c4f98834bf0d 100644 --- a/arch/arm64/kernel/paravirt.c +++ b/arch/arm64/kernel/paravirt.c @@ -13,10 +13,18 @@ * Author: Stefano Stabellini */ +#define pr_fmt(fmt) "arm-pv: " fmt + +#include +#include #include +#include #include +#include +#include #include #include +#include struct static_key paravirt_steal_enabled; struct static_key paravirt_steal_rq_enabled; @@ -28,3 +36,107 @@ struct paravirt_patch_template pv_ops = { EXPORT_SYMBOL_GPL(pv_time_ops); EXPORT_SYMBOL_GPL(pv_ops); + +DEFINE_PER_CPU(struct pvsched_vcpu_state, pvsched_vcpu_region) __aligned(64); +EXPORT_PER_CPU_SYMBOL(pvsched_vcpu_region); + +static bool kvm_vcpu_is_preempted(int cpu) +{ + struct pvsched_vcpu_state *reg; + u32 preempted; + + reg = &per_cpu(pvsched_vcpu_region, cpu); + if (!reg) { + pr_warn_once("PV sched enabled but not configured for cpu %d\n", + cpu); + return false; + } + + preempted = le32_to_cpu(READ_ONCE(reg->preempted)); + + return !!preempted; +} + +static int pvsched_vcpu_state_dying_cpu(unsigned int cpu) +{ + struct pvsched_vcpu_state *reg; + struct arm_smccc_res res; + + reg = this_cpu_ptr(&pvsched_vcpu_region); + if (!reg) + return -EFAULT; + + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_SCHED_IPA_RELEASE, &res); + memset(reg, 0, sizeof(*reg)); + + return 0; +} + +static int init_pvsched_vcpu_state(unsigned int cpu) +{ + struct pvsched_vcpu_state *reg; + struct arm_smccc_res res; + + reg = this_cpu_ptr(&pvsched_vcpu_region); + if (!reg) + return -EFAULT; + + /* Pass the memory address to host via hypercall */ + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_SCHED_IPA_INIT, + virt_to_phys(reg), &res); + + return 0; +} + +static int kvm_arm_init_pvsched(void) +{ + int ret; + + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, + "hypervisor/arm/pvsched:starting", + init_pvsched_vcpu_state, + pvsched_vcpu_state_dying_cpu); + + if (ret < 0) { + pr_warn("PV sched init failed\n"); + return ret; + } + + return 0; +} + +static bool has_kvm_pvsched(void) +{ + struct arm_smccc_res res; + + /* To detect the presence of PV sched support we require SMCCC 1.1+ */ + if (psci_ops.smccc_version < SMCCC_VERSION_1_1) + return false; + + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, + ARM_SMCCC_HV_PV_SCHED_FEATURES, &res); + + return (res.a0 == SMCCC_RET_SUCCESS); +} + +int __init pv_sched_init(void) +{ + int ret; + + if (is_hyp_mode_available()) + return 0; + + if (!has_kvm_pvsched()) { + pr_warn("PV sched is not available\n"); + return 0; + } + + ret = kvm_arm_init_pvsched(); + if (ret) + return ret; + + pv_ops.sched.vcpu_is_preempted = kvm_vcpu_is_preempted; + pr_info("using PV sched preempted\n"); + + return 0; +} diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 0325fbdfc046..ad3759b4f645 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -372,6 +372,8 @@ void __init setup_arch(char **cmdline_p) smp_init_cpus(); smp_build_mpidr_hash(); + pv_sched_init(); + #ifdef CONFIG_ARM64_SW_TTBR0_PAN /* * Make sure init_thread_info.ttbr0 always generates translation -- GitLab