diff options
Diffstat (limited to 'arch/arm64/kernel/paravirt.c')
| -rw-r--r-- | arch/arm64/kernel/paravirt.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c new file mode 100644 index 000000000..57c7c211f --- /dev/null +++ b/arch/arm64/kernel/paravirt.c @@ -0,0 +1,180 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * Copyright (C) 2013 Citrix Systems + * + * Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com> + */ + +#define pr_fmt(fmt) "arm-pv: " fmt + +#include <linux/arm-smccc.h> +#include <linux/cpuhotplug.h> +#include <linux/export.h> +#include <linux/io.h> +#include <linux/jump_label.h> +#include <linux/printk.h> +#include <linux/psci.h> +#include <linux/reboot.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/static_call.h> + +#include <asm/paravirt.h> +#include <asm/pvclock-abi.h> +#include <asm/smp_plat.h> + +struct static_key paravirt_steal_enabled; +struct static_key paravirt_steal_rq_enabled; + +static u64 native_steal_clock(int cpu) +{ + return 0; +} + +DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock); + +struct pv_time_stolen_time_region { + struct pvclock_vcpu_stolen_time __rcu *kaddr; +}; + +static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region); + +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); + +/* return stolen time in ns by asking the hypervisor */ +static u64 para_steal_clock(int cpu) +{ + struct pvclock_vcpu_stolen_time *kaddr = NULL; + struct pv_time_stolen_time_region *reg; + u64 ret = 0; + + reg = per_cpu_ptr(&stolen_time_region, cpu); + + /* + * paravirt_steal_clock() may be called before the CPU + * online notification callback runs. Until the callback + * has run we just return zero. + */ + rcu_read_lock(); + kaddr = rcu_dereference(reg->kaddr); + if (!kaddr) { + rcu_read_unlock(); + return 0; + } + + ret = le64_to_cpu(READ_ONCE(kaddr->stolen_time)); + rcu_read_unlock(); + return ret; +} + +static int stolen_time_cpu_down_prepare(unsigned int cpu) +{ + struct pvclock_vcpu_stolen_time *kaddr = NULL; + struct pv_time_stolen_time_region *reg; + + reg = this_cpu_ptr(&stolen_time_region); + if (!reg->kaddr) + return 0; + + kaddr = rcu_replace_pointer(reg->kaddr, NULL, true); + synchronize_rcu(); + memunmap(kaddr); + + return 0; +} + +static int stolen_time_cpu_online(unsigned int cpu) +{ + struct pvclock_vcpu_stolen_time *kaddr = NULL; + struct pv_time_stolen_time_region *reg; + struct arm_smccc_res res; + + reg = this_cpu_ptr(&stolen_time_region); + + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res); + + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) + return -EINVAL; + + kaddr = memremap(res.a0, + sizeof(struct pvclock_vcpu_stolen_time), + MEMREMAP_WB); + + rcu_assign_pointer(reg->kaddr, kaddr); + + if (!reg->kaddr) { + pr_warn("Failed to map stolen time data structure\n"); + return -ENOMEM; + } + + if (le32_to_cpu(kaddr->revision) != 0 || + le32_to_cpu(kaddr->attributes) != 0) { + pr_warn_once("Unexpected revision or attributes in stolen time data\n"); + return -ENXIO; + } + + return 0; +} + +static int __init pv_time_init_stolen_time(void) +{ + int ret; + + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, + "hypervisor/arm/pvtime:online", + stolen_time_cpu_online, + stolen_time_cpu_down_prepare); + if (ret < 0) + return ret; + return 0; +} + +static bool __init has_pv_steal_clock(void) +{ + struct arm_smccc_res res; + + /* To detect the presence of PV time support we require SMCCC 1.1+ */ + if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE) + return false; + + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, + ARM_SMCCC_HV_PV_TIME_FEATURES, &res); + + if (res.a0 != SMCCC_RET_SUCCESS) + return false; + + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_FEATURES, + ARM_SMCCC_HV_PV_TIME_ST, &res); + + return (res.a0 == SMCCC_RET_SUCCESS); +} + +int __init pv_time_init(void) +{ + int ret; + + if (!has_pv_steal_clock()) + return 0; + + ret = pv_time_init_stolen_time(); + if (ret) + return ret; + + static_call_update(pv_steal_clock, para_steal_clock); + + static_key_slow_inc(¶virt_steal_enabled); + if (steal_acc) + static_key_slow_inc(¶virt_steal_rq_enabled); + + pr_info("using stolen time PV\n"); + + return 0; +} |