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19bef63f95
During hotplug, the stolen time data structure is unmapped and memset.
There is a possibility of the timer IRQ being triggered before memset
and stolen time is getting updated as part of this timer IRQ handler. This
causes the below crash in timer handler -
[ 3457.473139][ C5] Unable to handle kernel paging request at virtual address ffffffc03df05148
...
[ 3458.154398][ C5] Call trace:
[ 3458.157648][ C5] para_steal_clock+0x30/0x50
[ 3458.162319][ C5] irqtime_account_process_tick+0x30/0x194
[ 3458.168148][ C5] account_process_tick+0x3c/0x280
[ 3458.173274][ C5] update_process_times+0x5c/0xf4
[ 3458.178311][ C5] tick_sched_timer+0x180/0x384
[ 3458.183164][ C5] __run_hrtimer+0x160/0x57c
[ 3458.187744][ C5] hrtimer_interrupt+0x258/0x684
[ 3458.192698][ C5] arch_timer_handler_virt+0x5c/0xa0
[ 3458.198002][ C5] handle_percpu_devid_irq+0xdc/0x414
[ 3458.203385][ C5] handle_domain_irq+0xa8/0x168
[ 3458.208241][ C5] gic_handle_irq.34493+0x54/0x244
[ 3458.213359][ C5] call_on_irq_stack+0x40/0x70
[ 3458.218125][ C5] do_interrupt_handler+0x60/0x9c
[ 3458.223156][ C5] el1_interrupt+0x34/0x64
[ 3458.227560][ C5] el1h_64_irq_handler+0x1c/0x2c
[ 3458.232503][ C5] el1h_64_irq+0x7c/0x80
[ 3458.236736][ C5] free_vmap_area_noflush+0x108/0x39c
[ 3458.242126][ C5] remove_vm_area+0xbc/0x118
[ 3458.246714][ C5] vm_remove_mappings+0x48/0x2a4
[ 3458.251656][ C5] __vunmap+0x154/0x278
[ 3458.255796][ C5] stolen_time_cpu_down_prepare+0xc0/0xd8
[ 3458.261542][ C5] cpuhp_invoke_callback+0x248/0xc34
[ 3458.266842][ C5] cpuhp_thread_fun+0x1c4/0x248
[ 3458.271696][ C5] smpboot_thread_fn+0x1b0/0x400
[ 3458.276638][ C5] kthread+0x17c/0x1e0
[ 3458.280691][ C5] ret_from_fork+0x10/0x20
As a fix, introduce rcu lock to update stolen time structure.
Fixes: 75df529bec
("arm64: paravirt: Initialize steal time when cpu is online")
Cc: stable@vger.kernel.org
Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Link: https://lore.kernel.org/r/20220513174654.362169-1-quic_eberman@quicinc.com
Signed-off-by: Will Deacon <will@kernel.org>
181 lines
3.8 KiB
C
181 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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*
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* Copyright (C) 2013 Citrix Systems
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*
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* Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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*/
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#define pr_fmt(fmt) "arm-pv: " fmt
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#include <linux/arm-smccc.h>
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#include <linux/cpuhotplug.h>
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#include <linux/export.h>
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#include <linux/io.h>
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#include <linux/jump_label.h>
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#include <linux/printk.h>
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#include <linux/psci.h>
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#include <linux/reboot.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/static_call.h>
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#include <asm/paravirt.h>
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#include <asm/pvclock-abi.h>
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#include <asm/smp_plat.h>
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struct static_key paravirt_steal_enabled;
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struct static_key paravirt_steal_rq_enabled;
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static u64 native_steal_clock(int cpu)
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{
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return 0;
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}
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DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
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struct pv_time_stolen_time_region {
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struct pvclock_vcpu_stolen_time __rcu *kaddr;
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};
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static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
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static bool steal_acc = true;
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static int __init parse_no_stealacc(char *arg)
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{
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steal_acc = false;
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return 0;
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}
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early_param("no-steal-acc", parse_no_stealacc);
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/* return stolen time in ns by asking the hypervisor */
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static u64 para_steal_clock(int cpu)
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{
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struct pvclock_vcpu_stolen_time *kaddr = NULL;
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struct pv_time_stolen_time_region *reg;
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u64 ret = 0;
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reg = per_cpu_ptr(&stolen_time_region, cpu);
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/*
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* paravirt_steal_clock() may be called before the CPU
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* online notification callback runs. Until the callback
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* has run we just return zero.
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*/
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rcu_read_lock();
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kaddr = rcu_dereference(reg->kaddr);
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if (!kaddr) {
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rcu_read_unlock();
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return 0;
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}
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ret = le64_to_cpu(READ_ONCE(kaddr->stolen_time));
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rcu_read_unlock();
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return ret;
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}
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static int stolen_time_cpu_down_prepare(unsigned int cpu)
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{
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struct pvclock_vcpu_stolen_time *kaddr = NULL;
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struct pv_time_stolen_time_region *reg;
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reg = this_cpu_ptr(&stolen_time_region);
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if (!reg->kaddr)
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return 0;
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kaddr = rcu_replace_pointer(reg->kaddr, NULL, true);
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synchronize_rcu();
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memunmap(kaddr);
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return 0;
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}
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static int stolen_time_cpu_online(unsigned int cpu)
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{
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struct pvclock_vcpu_stolen_time *kaddr = NULL;
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struct pv_time_stolen_time_region *reg;
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struct arm_smccc_res res;
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reg = this_cpu_ptr(&stolen_time_region);
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arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res);
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if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
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return -EINVAL;
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kaddr = memremap(res.a0,
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sizeof(struct pvclock_vcpu_stolen_time),
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MEMREMAP_WB);
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rcu_assign_pointer(reg->kaddr, kaddr);
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if (!reg->kaddr) {
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pr_warn("Failed to map stolen time data structure\n");
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return -ENOMEM;
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}
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if (le32_to_cpu(kaddr->revision) != 0 ||
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le32_to_cpu(kaddr->attributes) != 0) {
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pr_warn_once("Unexpected revision or attributes in stolen time data\n");
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return -ENXIO;
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}
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return 0;
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}
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static int __init pv_time_init_stolen_time(void)
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{
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int ret;
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ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
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"hypervisor/arm/pvtime:online",
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stolen_time_cpu_online,
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stolen_time_cpu_down_prepare);
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if (ret < 0)
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return ret;
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return 0;
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}
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static bool __init has_pv_steal_clock(void)
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{
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struct arm_smccc_res res;
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/* To detect the presence of PV time support we require SMCCC 1.1+ */
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if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
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return false;
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arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
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ARM_SMCCC_HV_PV_TIME_FEATURES, &res);
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if (res.a0 != SMCCC_RET_SUCCESS)
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return false;
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arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_FEATURES,
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ARM_SMCCC_HV_PV_TIME_ST, &res);
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return (res.a0 == SMCCC_RET_SUCCESS);
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}
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int __init pv_time_init(void)
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{
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int ret;
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if (!has_pv_steal_clock())
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return 0;
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ret = pv_time_init_stolen_time();
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if (ret)
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return ret;
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static_call_update(pv_steal_clock, para_steal_clock);
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static_key_slow_inc(¶virt_steal_enabled);
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if (steal_acc)
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static_key_slow_inc(¶virt_steal_rq_enabled);
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pr_info("using stolen time PV\n");
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return 0;
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}
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