diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 6 | ||||
| -rw-r--r-- | arch/loongarch/Kconfig | 11 | ||||
| -rw-r--r-- | arch/loongarch/include/asm/paravirt.h | 5 | ||||
| -rw-r--r-- | arch/loongarch/kernel/paravirt.c | 145 | ||||
| -rw-r--r-- | arch/loongarch/kernel/time.c | 2 |
5 files changed, 166 insertions, 3 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 27ec49af1bf2..941b3105248d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4073,9 +4073,9 @@ prediction) vulnerability. System may allow data leaks with this option. - no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,EARLY] Disable - paravirtualized steal time accounting. steal time is - computed, but won't influence scheduler behaviour + no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,LOONGARCH,EARLY] + Disable paravirtualized steal time accounting. steal time + is computed, but won't influence scheduler behaviour nosync [HW,M68K] Disables sync negotiation for all devices. diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index ddc042895d01..b81d0eba5c7e 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -649,6 +649,17 @@ config PARAVIRT over full virtualization. However, when run without a hypervisor the kernel is theoretically slower and slightly larger. +config PARAVIRT_TIME_ACCOUNTING + bool "Paravirtual steal time accounting" + depends on PARAVIRT + help + Select this option to enable fine granularity task steal time + accounting. Time spent executing other tasks in parallel with + the current vCPU is discounted from the vCPU power. To account for + that, there can be a small performance impact. + + If in doubt, say N here. + endmenu config ARCH_SELECT_MEMORY_MODEL diff --git a/arch/loongarch/include/asm/paravirt.h b/arch/loongarch/include/asm/paravirt.h index 0965710f47f2..dddec49671ae 100644 --- a/arch/loongarch/include/asm/paravirt.h +++ b/arch/loongarch/include/asm/paravirt.h @@ -18,6 +18,7 @@ static inline u64 paravirt_steal_clock(int cpu) } int __init pv_ipi_init(void); +int __init pv_time_init(void); #else @@ -26,5 +27,9 @@ static inline int pv_ipi_init(void) return 0; } +static inline int pv_time_init(void) +{ + return 0; +} #endif // CONFIG_PARAVIRT #endif diff --git a/arch/loongarch/kernel/paravirt.c b/arch/loongarch/kernel/paravirt.c index 1633ed4f692f..9abe8b71aa48 100644 --- a/arch/loongarch/kernel/paravirt.c +++ b/arch/loongarch/kernel/paravirt.c @@ -4,11 +4,14 @@ #include <linux/interrupt.h> #include <linux/jump_label.h> #include <linux/kvm_para.h> +#include <linux/reboot.h> #include <linux/static_call.h> #include <asm/paravirt.h> +static int has_steal_clock; struct static_key paravirt_steal_enabled; struct static_key paravirt_steal_rq_enabled; +static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64); static u64 native_steal_clock(int cpu) { @@ -17,6 +20,34 @@ static u64 native_steal_clock(int cpu) DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock); +static bool steal_acc = true; + +static int __init parse_no_stealacc(char *arg) +{ + steal_acc = false; + return 0; +} +early_param("no-steal-acc", parse_no_stealacc); + +static u64 paravt_steal_clock(int cpu) +{ + int version; + u64 steal; + struct kvm_steal_time *src; + + src = &per_cpu(steal_time, cpu); + do { + + version = src->version; + virt_rmb(); /* Make sure that the version is read before the steal */ + steal = src->steal; + virt_rmb(); /* Make sure that the steal is read before the next version */ + + } while ((version & 1) || (version != src->version)); + + return steal; +} + #ifdef CONFIG_SMP static void pv_send_ipi_single(int cpu, unsigned int action) { @@ -149,3 +180,117 @@ int __init pv_ipi_init(void) return 0; } + +static int pv_enable_steal_time(void) +{ + int cpu = smp_processor_id(); + unsigned long addr; + struct kvm_steal_time *st; + + if (!has_steal_clock) + return -EPERM; + + st = &per_cpu(steal_time, cpu); + addr = per_cpu_ptr_to_phys(st); + + /* The whole structure kvm_steal_time should be in one page */ + if (PFN_DOWN(addr) != PFN_DOWN(addr + sizeof(*st))) { + pr_warn("Illegal PV steal time addr %lx\n", addr); + return -EFAULT; + } + + addr |= KVM_STEAL_PHYS_VALID; + kvm_hypercall2(KVM_HCALL_FUNC_NOTIFY, KVM_FEATURE_STEAL_TIME, addr); + + return 0; +} + +static void pv_disable_steal_time(void) +{ + if (has_steal_clock) + kvm_hypercall2(KVM_HCALL_FUNC_NOTIFY, KVM_FEATURE_STEAL_TIME, 0); +} + +#ifdef CONFIG_SMP +static int pv_time_cpu_online(unsigned int cpu) +{ + unsigned long flags; + + local_irq_save(flags); + pv_enable_steal_time(); + local_irq_restore(flags); + + return 0; +} + +static int pv_time_cpu_down_prepare(unsigned int cpu) +{ + unsigned long flags; + + local_irq_save(flags); + pv_disable_steal_time(); + local_irq_restore(flags); + + return 0; +} +#endif + +static void pv_cpu_reboot(void *unused) +{ + pv_disable_steal_time(); +} + +static int pv_reboot_notify(struct notifier_block *nb, unsigned long code, void *unused) +{ + on_each_cpu(pv_cpu_reboot, NULL, 1); + return NOTIFY_DONE; +} + +static struct notifier_block pv_reboot_nb = { + .notifier_call = pv_reboot_notify, +}; + +int __init pv_time_init(void) +{ + int r, feature; + + if (!cpu_has_hypervisor) + return 0; + if (!kvm_para_available()) + return 0; + + feature = read_cpucfg(CPUCFG_KVM_FEATURE); + if (!(feature & KVM_FEATURE_STEAL_TIME)) + return 0; + + has_steal_clock = 1; + r = pv_enable_steal_time(); + if (r < 0) { + has_steal_clock = 0; + return 0; + } + register_reboot_notifier(&pv_reboot_nb); + +#ifdef CONFIG_SMP + r = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "loongarch/pv_time:online", + pv_time_cpu_online, pv_time_cpu_down_prepare); + if (r < 0) { + has_steal_clock = 0; + pr_err("Failed to install cpu hotplug callbacks\n"); + return r; + } +#endif + + static_call_update(pv_steal_clock, paravt_steal_clock); + + static_key_slow_inc(¶virt_steal_enabled); +#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING + if (steal_acc) + static_key_slow_inc(¶virt_steal_rq_enabled); +#endif + + pr_info("Using paravirt steal-time\n"); + + return 0; +} diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c index fd5354f9be7c..46d7d40c87e3 100644 --- a/arch/loongarch/kernel/time.c +++ b/arch/loongarch/kernel/time.c @@ -15,6 +15,7 @@ #include <asm/cpu-features.h> #include <asm/loongarch.h> +#include <asm/paravirt.h> #include <asm/time.h> u64 cpu_clock_freq; @@ -214,4 +215,5 @@ void __init time_init(void) constant_clockevent_init(); constant_clocksource_init(); + pv_time_init(); } |