xen/vcpu: Handle xen_vcpu_setup() failure at boot
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>
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index aae3253..1ea598e 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -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,