43 lines
1.0 KiB
C
43 lines
1.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* Preemptible hypercalls
|
|
*
|
|
* Copyright (C) 2014 Citrix Systems R&D ltd.
|
|
*/
|
|
|
|
#include <linux/sched.h>
|
|
#include <xen/xen-ops.h>
|
|
|
|
#ifndef CONFIG_PREEMPTION
|
|
|
|
/*
|
|
* Some hypercalls issued by the toolstack can take many 10s of
|
|
* seconds. Allow tasks running hypercalls via the privcmd driver to
|
|
* be voluntarily preempted even if full kernel preemption is
|
|
* disabled.
|
|
*
|
|
* Such preemptible hypercalls are bracketed by
|
|
* xen_preemptible_hcall_begin() and xen_preemptible_hcall_end()
|
|
* calls.
|
|
*/
|
|
|
|
DEFINE_PER_CPU(bool, xen_in_preemptible_hcall);
|
|
EXPORT_SYMBOL_GPL(xen_in_preemptible_hcall);
|
|
|
|
asmlinkage __visible void xen_maybe_preempt_hcall(void)
|
|
{
|
|
if (unlikely(__this_cpu_read(xen_in_preemptible_hcall)
|
|
&& need_resched())) {
|
|
/*
|
|
* Clear flag as we may be rescheduled on a different
|
|
* cpu.
|
|
*/
|
|
__this_cpu_write(xen_in_preemptible_hcall, false);
|
|
local_irq_enable();
|
|
cond_resched();
|
|
local_irq_disable();
|
|
__this_cpu_write(xen_in_preemptible_hcall, true);
|
|
}
|
|
}
|
|
#endif /* CONFIG_PREEMPTION */
|