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xen/vcpu: Handle xen_vcpu_setup() failure at boot

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On PVH, PVHVM, at failure in the VCPUOP_register_vcpu_info hypercall
we limit the number of cpus to to MAX_VIRT_CPUS. However, if this
failure had occurred for a cpu beyond MAX_VIRT_CPUS, we continue
to function with > MAX_VIRT_CPUS.

This leads to problems at the next save/restore cycle when there
are > MAX_VIRT_CPUS threads going into stop_machine() but coming
back up there's valid state for only the first MAX_VIRT_CPUS.

This patch pulls the excess CPUs down via cpu_down().

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Ankur Arora 2017-06-02 17:06:02 -07:00 committed by Juergen Gross
parent c9b5d98b25
commit ae03900105
4 changed files with 35 additions and 5 deletions
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31
arch/x86/xen/smp.c
View File

@ -1,4 +1,5 @@
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/slab.h>
#include <linux/cpumask.h>
#include <linux/percpu.h>
@ -114,6 +115,36 @@ int xen_smp_intr_init(unsigned int cpu)
return rc;
}
void __init xen_smp_cpus_done(unsigned int max_cpus)
{
int cpu, rc, count = 0;
if (xen_hvm_domain())
native_smp_cpus_done(max_cpus);
if (xen_have_vcpu_info_placement)
return;
for_each_online_cpu(cpu) {
if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS)
continue;
rc = cpu_down(cpu);
if (rc == 0) {
/*
* Reset vcpu_info so this cpu cannot be onlined again.
*/
xen_vcpu_info_reset(cpu);
count++;
} else {
pr_warn("%s: failed to bring CPU %d down, error %d\n",
__func__, cpu, rc);
}
}
WARN(count, "%s: brought %d CPUs offline\n", __func__, count);
}
void xen_smp_send_reschedule(int cpu)
{
xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);

2
arch/x86/xen/smp.h
View File

@ -14,6 +14,8 @@ extern void xen_smp_intr_free(unsigned int cpu);
int xen_smp_intr_init_pv(unsigned int cpu);
void xen_smp_intr_free_pv(unsigned int cpu);
void xen_smp_cpus_done(unsigned int max_cpus);
void xen_smp_send_reschedule(int cpu);
void xen_smp_send_call_function_ipi(const struct cpumask *mask);
void xen_smp_send_call_function_single_ipi(int cpu);

1
arch/x86/xen/smp_hvm.c
View File

@ -71,4 +71,5 @@ void __init xen_hvm_smp_init(void)
smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi;
smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi;
smp_ops.smp_prepare_boot_cpu = xen_hvm_smp_prepare_boot_cpu;
smp_ops.smp_cpus_done = xen_smp_cpus_done;
}

6
arch/x86/xen/smp_pv.c
View File

@ -371,10 +371,6 @@ static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle)
return 0;
}
static void xen_pv_smp_cpus_done(unsigned int max_cpus)
{
}
#ifdef CONFIG_HOTPLUG_CPU
static int xen_pv_cpu_disable(void)
{
@ -469,7 +465,7 @@ static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
static const struct smp_ops xen_smp_ops __initconst = {
.smp_prepare_boot_cpu = xen_pv_smp_prepare_boot_cpu,
.smp_prepare_cpus = xen_pv_smp_prepare_cpus,
.smp_cpus_done = xen_pv_smp_cpus_done,
.smp_cpus_done = xen_smp_cpus_done,
.cpu_up = xen_pv_cpu_up,
.cpu_die = xen_pv_cpu_die,