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![Martin Schwidefsky](/assets/img/avatar_default.png)
Define TIF_ISOLATE_BP and TIF_ISOLATE_BP_GUEST and add the necessary plumbing in entry.S to be able to run user space and KVM guests with limited branch prediction. To switch a user space process to limited branch prediction the s390_isolate_bp() function has to be call, and to run a vCPU of a KVM guest associated with the current task with limited branch prediction call s390_isolate_bp_guest(). Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
217 lines
4.8 KiB
C
217 lines
4.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*/
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#define KMSG_COMPONENT "cpu"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/cpufeature.h>
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#include <linux/bitops.h>
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#include <linux/kernel.h>
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#include <linux/sched/mm.h>
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#include <linux/init.h>
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#include <linux/seq_file.h>
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#include <linux/mm_types.h>
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#include <linux/delay.h>
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#include <linux/cpu.h>
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#include <asm/diag.h>
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#include <asm/facility.h>
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#include <asm/elf.h>
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#include <asm/lowcore.h>
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#include <asm/param.h>
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#include <asm/smp.h>
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struct cpu_info {
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unsigned int cpu_mhz_dynamic;
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unsigned int cpu_mhz_static;
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struct cpuid cpu_id;
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};
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static DEFINE_PER_CPU(struct cpu_info, cpu_info);
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static bool machine_has_cpu_mhz;
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void __init cpu_detect_mhz_feature(void)
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{
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if (test_facility(34) && __ecag(ECAG_CPU_ATTRIBUTE, 0) != -1UL)
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machine_has_cpu_mhz = true;
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}
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static void update_cpu_mhz(void *arg)
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{
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unsigned long mhz;
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struct cpu_info *c;
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mhz = __ecag(ECAG_CPU_ATTRIBUTE, 0);
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c = this_cpu_ptr(&cpu_info);
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c->cpu_mhz_dynamic = mhz >> 32;
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c->cpu_mhz_static = mhz & 0xffffffff;
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}
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void s390_update_cpu_mhz(void)
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{
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s390_adjust_jiffies();
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if (machine_has_cpu_mhz)
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on_each_cpu(update_cpu_mhz, NULL, 0);
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}
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void notrace cpu_relax_yield(void)
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{
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if (!smp_cpu_mtid && MACHINE_HAS_DIAG44) {
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diag_stat_inc(DIAG_STAT_X044);
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asm volatile("diag 0,0,0x44");
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}
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barrier();
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}
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EXPORT_SYMBOL(cpu_relax_yield);
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/*
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* cpu_init - initializes state that is per-CPU.
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*/
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void cpu_init(void)
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{
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struct cpuid *id = this_cpu_ptr(&cpu_info.cpu_id);
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get_cpu_id(id);
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if (machine_has_cpu_mhz)
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update_cpu_mhz(NULL);
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mmgrab(&init_mm);
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current->active_mm = &init_mm;
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BUG_ON(current->mm);
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enter_lazy_tlb(&init_mm, current);
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}
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/*
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* cpu_have_feature - Test CPU features on module initialization
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*/
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int cpu_have_feature(unsigned int num)
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{
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return elf_hwcap & (1UL << num);
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}
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EXPORT_SYMBOL(cpu_have_feature);
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static void show_facilities(struct seq_file *m)
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{
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unsigned int bit;
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long *facilities;
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facilities = (long *)&S390_lowcore.stfle_fac_list;
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seq_puts(m, "facilities :");
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for_each_set_bit_inv(bit, facilities, MAX_FACILITY_BIT)
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seq_printf(m, " %d", bit);
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seq_putc(m, '\n');
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}
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static void show_cpu_summary(struct seq_file *m, void *v)
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{
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static const char *hwcap_str[] = {
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"esan3", "zarch", "stfle", "msa", "ldisp", "eimm", "dfp",
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"edat", "etf3eh", "highgprs", "te", "vx", "vxd", "vxe", "gs"
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};
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static const char * const int_hwcap_str[] = {
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"sie"
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};
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int i, cpu;
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seq_printf(m, "vendor_id : IBM/S390\n"
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"# processors : %i\n"
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"bogomips per cpu: %lu.%02lu\n",
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num_online_cpus(), loops_per_jiffy/(500000/HZ),
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(loops_per_jiffy/(5000/HZ))%100);
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seq_printf(m, "max thread id : %d\n", smp_cpu_mtid);
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seq_puts(m, "features\t: ");
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for (i = 0; i < ARRAY_SIZE(hwcap_str); i++)
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if (hwcap_str[i] && (elf_hwcap & (1UL << i)))
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seq_printf(m, "%s ", hwcap_str[i]);
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for (i = 0; i < ARRAY_SIZE(int_hwcap_str); i++)
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if (int_hwcap_str[i] && (int_hwcap & (1UL << i)))
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seq_printf(m, "%s ", int_hwcap_str[i]);
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seq_puts(m, "\n");
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show_facilities(m);
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show_cacheinfo(m);
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for_each_online_cpu(cpu) {
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struct cpuid *id = &per_cpu(cpu_info.cpu_id, cpu);
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seq_printf(m, "processor %d: "
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"version = %02X, "
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"identification = %06X, "
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"machine = %04X\n",
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cpu, id->version, id->ident, id->machine);
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}
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}
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static void show_cpu_mhz(struct seq_file *m, unsigned long n)
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{
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struct cpu_info *c = per_cpu_ptr(&cpu_info, n);
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seq_printf(m, "cpu MHz dynamic : %d\n", c->cpu_mhz_dynamic);
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seq_printf(m, "cpu MHz static : %d\n", c->cpu_mhz_static);
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}
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/*
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* show_cpuinfo - Get information on one CPU for use by procfs.
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*/
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static int show_cpuinfo(struct seq_file *m, void *v)
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{
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unsigned long n = (unsigned long) v - 1;
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if (!n)
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show_cpu_summary(m, v);
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if (!machine_has_cpu_mhz)
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return 0;
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seq_printf(m, "\ncpu number : %ld\n", n);
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show_cpu_mhz(m, n);
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return 0;
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}
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static inline void *c_update(loff_t *pos)
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{
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if (*pos)
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*pos = cpumask_next(*pos - 1, cpu_online_mask);
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return *pos < nr_cpu_ids ? (void *)*pos + 1 : NULL;
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}
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static void *c_start(struct seq_file *m, loff_t *pos)
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{
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get_online_cpus();
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return c_update(pos);
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}
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static void *c_next(struct seq_file *m, void *v, loff_t *pos)
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{
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++*pos;
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return c_update(pos);
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}
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static void c_stop(struct seq_file *m, void *v)
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{
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put_online_cpus();
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}
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const struct seq_operations cpuinfo_op = {
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.start = c_start,
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.next = c_next,
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.stop = c_stop,
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.show = show_cpuinfo,
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};
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int s390_isolate_bp(void)
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{
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if (!test_facility(82))
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return -EOPNOTSUPP;
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set_thread_flag(TIF_ISOLATE_BP);
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return 0;
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}
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EXPORT_SYMBOL(s390_isolate_bp);
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int s390_isolate_bp_guest(void)
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{
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if (!test_facility(82))
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return -EOPNOTSUPP;
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set_thread_flag(TIF_ISOLATE_BP_GUEST);
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return 0;
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}
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EXPORT_SYMBOL(s390_isolate_bp_guest);
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