cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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paravirt.c (3909B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 *
      4 * Copyright (C) 2013 Citrix Systems
      5 *
      6 * Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
      7 */
      8
      9#define pr_fmt(fmt) "arm-pv: " fmt
     10
     11#include <linux/arm-smccc.h>
     12#include <linux/cpuhotplug.h>
     13#include <linux/export.h>
     14#include <linux/io.h>
     15#include <linux/jump_label.h>
     16#include <linux/printk.h>
     17#include <linux/psci.h>
     18#include <linux/reboot.h>
     19#include <linux/slab.h>
     20#include <linux/types.h>
     21#include <linux/static_call.h>
     22
     23#include <asm/paravirt.h>
     24#include <asm/pvclock-abi.h>
     25#include <asm/smp_plat.h>
     26
     27struct static_key paravirt_steal_enabled;
     28struct static_key paravirt_steal_rq_enabled;
     29
     30static u64 native_steal_clock(int cpu)
     31{
     32	return 0;
     33}
     34
     35DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
     36
     37struct pv_time_stolen_time_region {
     38	struct pvclock_vcpu_stolen_time __rcu *kaddr;
     39};
     40
     41static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
     42
     43static bool steal_acc = true;
     44static int __init parse_no_stealacc(char *arg)
     45{
     46	steal_acc = false;
     47	return 0;
     48}
     49
     50early_param("no-steal-acc", parse_no_stealacc);
     51
     52/* return stolen time in ns by asking the hypervisor */
     53static u64 para_steal_clock(int cpu)
     54{
     55	struct pvclock_vcpu_stolen_time *kaddr = NULL;
     56	struct pv_time_stolen_time_region *reg;
     57	u64 ret = 0;
     58
     59	reg = per_cpu_ptr(&stolen_time_region, cpu);
     60
     61	/*
     62	 * paravirt_steal_clock() may be called before the CPU
     63	 * online notification callback runs. Until the callback
     64	 * has run we just return zero.
     65	 */
     66	rcu_read_lock();
     67	kaddr = rcu_dereference(reg->kaddr);
     68	if (!kaddr) {
     69		rcu_read_unlock();
     70		return 0;
     71	}
     72
     73	ret = le64_to_cpu(READ_ONCE(kaddr->stolen_time));
     74	rcu_read_unlock();
     75	return ret;
     76}
     77
     78static int stolen_time_cpu_down_prepare(unsigned int cpu)
     79{
     80	struct pvclock_vcpu_stolen_time *kaddr = NULL;
     81	struct pv_time_stolen_time_region *reg;
     82
     83	reg = this_cpu_ptr(&stolen_time_region);
     84	if (!reg->kaddr)
     85		return 0;
     86
     87	kaddr = rcu_replace_pointer(reg->kaddr, NULL, true);
     88	synchronize_rcu();
     89	memunmap(kaddr);
     90
     91	return 0;
     92}
     93
     94static int stolen_time_cpu_online(unsigned int cpu)
     95{
     96	struct pvclock_vcpu_stolen_time *kaddr = NULL;
     97	struct pv_time_stolen_time_region *reg;
     98	struct arm_smccc_res res;
     99
    100	reg = this_cpu_ptr(&stolen_time_region);
    101
    102	arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res);
    103
    104	if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
    105		return -EINVAL;
    106
    107	kaddr = memremap(res.a0,
    108			      sizeof(struct pvclock_vcpu_stolen_time),
    109			      MEMREMAP_WB);
    110
    111	rcu_assign_pointer(reg->kaddr, kaddr);
    112
    113	if (!reg->kaddr) {
    114		pr_warn("Failed to map stolen time data structure\n");
    115		return -ENOMEM;
    116	}
    117
    118	if (le32_to_cpu(kaddr->revision) != 0 ||
    119	    le32_to_cpu(kaddr->attributes) != 0) {
    120		pr_warn_once("Unexpected revision or attributes in stolen time data\n");
    121		return -ENXIO;
    122	}
    123
    124	return 0;
    125}
    126
    127static int __init pv_time_init_stolen_time(void)
    128{
    129	int ret;
    130
    131	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
    132				"hypervisor/arm/pvtime:online",
    133				stolen_time_cpu_online,
    134				stolen_time_cpu_down_prepare);
    135	if (ret < 0)
    136		return ret;
    137	return 0;
    138}
    139
    140static bool __init has_pv_steal_clock(void)
    141{
    142	struct arm_smccc_res res;
    143
    144	/* To detect the presence of PV time support we require SMCCC 1.1+ */
    145	if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
    146		return false;
    147
    148	arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
    149			     ARM_SMCCC_HV_PV_TIME_FEATURES, &res);
    150
    151	if (res.a0 != SMCCC_RET_SUCCESS)
    152		return false;
    153
    154	arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_FEATURES,
    155			     ARM_SMCCC_HV_PV_TIME_ST, &res);
    156
    157	return (res.a0 == SMCCC_RET_SUCCESS);
    158}
    159
    160int __init pv_time_init(void)
    161{
    162	int ret;
    163
    164	if (!has_pv_steal_clock())
    165		return 0;
    166
    167	ret = pv_time_init_stolen_time();
    168	if (ret)
    169		return ret;
    170
    171	static_call_update(pv_steal_clock, para_steal_clock);
    172
    173	static_key_slow_inc(&paravirt_steal_enabled);
    174	if (steal_acc)
    175		static_key_slow_inc(&paravirt_steal_rq_enabled);
    176
    177	pr_info("using stolen time PV\n");
    178
    179	return 0;
    180}