1// SPDX-License-Identifier: GPL-2.0
 2#include <linux/hardirq.h>
 3
 4#include <asm/x86_init.h>
 5
 6#include <xen/interface/xen.h>
 7#include <xen/interface/sched.h>
 8#include <xen/interface/vcpu.h>
 9#include <xen/features.h>
10#include <xen/events.h>
11
12#include <asm/xen/hypercall.h>
13#include <asm/xen/hypervisor.h>
14
15#include "xen-ops.h"
16
17/*
18 * Force a proper event-channel callback from Xen after clearing the
19 * callback mask. We do this in a very simple manner, by making a call
20 * down into Xen. The pending flag will be checked by Xen on return.
21 */
22noinstr void xen_force_evtchn_callback(void)
23{
24	(void)HYPERVISOR_xen_version(0, NULL);
25}
26
27static noinstr void xen_safe_halt(void)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
28{
29	/* Blocking includes an implicit local_irq_enable(). */
30	if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
31		BUG();
32}
33
34static void xen_halt(void)
35{
36	if (irqs_disabled())
37		HYPERVISOR_vcpu_op(VCPUOP_down,
38				   xen_vcpu_nr(smp_processor_id()), NULL);
39	else
40		xen_safe_halt();
41}
42
43static const typeof(pv_ops) xen_irq_ops __initconst = {
44	.irq = {
45		/* Initial interrupt flag handling only called while interrupts off. */
46		.save_fl = __PV_IS_CALLEE_SAVE(paravirt_ret0),
47		.irq_disable = __PV_IS_CALLEE_SAVE(paravirt_nop),
48		.irq_enable = __PV_IS_CALLEE_SAVE(BUG_func),
49
50		.safe_halt = xen_safe_halt,
51		.halt = xen_halt,
52	},
53};
54
55void __init xen_init_irq_ops(void)
56{
57	pv_ops.irq = xen_irq_ops.irq;
58	x86_init.irqs.intr_init = xen_init_IRQ;
59}

  1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/hardirq.h>
  3
  4#include <asm/x86_init.h>
  5
  6#include <xen/interface/xen.h>
  7#include <xen/interface/sched.h>
  8#include <xen/interface/vcpu.h>
  9#include <xen/features.h>
 10#include <xen/events.h>
 11
 12#include <asm/xen/hypercall.h>
 13#include <asm/xen/hypervisor.h>
 14
 15#include "xen-ops.h"
 16
 17/*
 18 * Force a proper event-channel callback from Xen after clearing the
 19 * callback mask. We do this in a very simple manner, by making a call
 20 * down into Xen. The pending flag will be checked by Xen on return.
 21 */
 22void xen_force_evtchn_callback(void)
 23{
 24	(void)HYPERVISOR_xen_version(0, NULL);
 25}
 26
 27asmlinkage __visible unsigned long xen_save_fl(void)
 28{
 29	struct vcpu_info *vcpu;
 30	unsigned long flags;
 31
 32	vcpu = this_cpu_read(xen_vcpu);
 33
 34	/* flag has opposite sense of mask */
 35	flags = !vcpu->evtchn_upcall_mask;
 36
 37	/* convert to IF type flag
 38	   -0 -> 0x00000000
 39	   -1 -> 0xffffffff
 40	*/
 41	return (-flags) & X86_EFLAGS_IF;
 42}
 43PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl);
 44
 45__visible void xen_restore_fl(unsigned long flags)
 46{
 47	struct vcpu_info *vcpu;
 48
 49	/* convert from IF type flag */
 50	flags = !(flags & X86_EFLAGS_IF);
 51
 52	/* See xen_irq_enable() for why preemption must be disabled. */
 53	preempt_disable();
 54	vcpu = this_cpu_read(xen_vcpu);
 55	vcpu->evtchn_upcall_mask = flags;
 56
 57	if (flags == 0) {
 58		barrier(); /* unmask then check (avoid races) */
 59		if (unlikely(vcpu->evtchn_upcall_pending))
 60			xen_force_evtchn_callback();
 61		preempt_enable();
 62	} else
 63		preempt_enable_no_resched();
 64}
 65PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl);
 66
 67asmlinkage __visible void xen_irq_disable(void)
 68{
 69	/* There's a one instruction preempt window here.  We need to
 70	   make sure we're don't switch CPUs between getting the vcpu
 71	   pointer and updating the mask. */
 72	preempt_disable();
 73	this_cpu_read(xen_vcpu)->evtchn_upcall_mask = 1;
 74	preempt_enable_no_resched();
 75}
 76PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable);
 77
 78asmlinkage __visible void xen_irq_enable(void)
 79{
 80	struct vcpu_info *vcpu;
 81
 82	/*
 83	 * We may be preempted as soon as vcpu->evtchn_upcall_mask is
 84	 * cleared, so disable preemption to ensure we check for
 85	 * events on the VCPU we are still running on.
 86	 */
 87	preempt_disable();
 88
 89	vcpu = this_cpu_read(xen_vcpu);
 90	vcpu->evtchn_upcall_mask = 0;
 91
 92	/* Doesn't matter if we get preempted here, because any
 93	   pending event will get dealt with anyway. */
 94
 95	barrier(); /* unmask then check (avoid races) */
 96	if (unlikely(vcpu->evtchn_upcall_pending))
 97		xen_force_evtchn_callback();
 98
 99	preempt_enable();
100}
101PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable);
102
103static void xen_safe_halt(void)
104{
105	/* Blocking includes an implicit local_irq_enable(). */
106	if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
107		BUG();
108}
109
110static void xen_halt(void)
111{
112	if (irqs_disabled())
113		HYPERVISOR_vcpu_op(VCPUOP_down,
114				   xen_vcpu_nr(smp_processor_id()), NULL);
115	else
116		xen_safe_halt();
117}
118
119static const struct pv_irq_ops xen_irq_ops __initconst = {
120	.save_fl = PV_CALLEE_SAVE(xen_save_fl),
121	.restore_fl = PV_CALLEE_SAVE(xen_restore_fl),
122	.irq_disable = PV_CALLEE_SAVE(xen_irq_disable),
123	.irq_enable = PV_CALLEE_SAVE(xen_irq_enable),
124
125	.safe_halt = xen_safe_halt,
126	.halt = xen_halt,
 
 
127};
128
129void __init xen_init_irq_ops(void)
130{
131	pv_ops.irq = xen_irq_ops;
132	x86_init.irqs.intr_init = xen_init_IRQ;
133}