1#include <linux/hardirq.h>
2
3#include <asm/x86_init.h>
4
5#include <xen/interface/xen.h>
6#include <xen/interface/sched.h>
7#include <xen/interface/vcpu.h>
8#include <xen/features.h>
9#include <xen/events.h>
10
11#include <asm/xen/hypercall.h>
12#include <asm/xen/hypervisor.h>
13
14#include "xen-ops.h"
15
16/*
17 * Force a proper event-channel callback from Xen after clearing the
18 * callback mask. We do this in a very simple manner, by making a call
19 * down into Xen. The pending flag will be checked by Xen on return.
20 */
21void xen_force_evtchn_callback(void)
22{
23	(void)HYPERVISOR_xen_version(0, NULL);
24}
25
26asmlinkage __visible unsigned long xen_save_fl(void)
27{
28	struct vcpu_info *vcpu;
29	unsigned long flags;
30
31	vcpu = this_cpu_read(xen_vcpu);
32
33	/* flag has opposite sense of mask */
34	flags = !vcpu->evtchn_upcall_mask;
35
36	/* convert to IF type flag
37	   -0 -> 0x00000000
38	   -1 -> 0xffffffff
39	*/
40	return (-flags) & X86_EFLAGS_IF;
41}
42PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl);
43
44__visible void xen_restore_fl(unsigned long flags)
45{
46	struct vcpu_info *vcpu;
47
48	/* convert from IF type flag */
49	flags = !(flags & X86_EFLAGS_IF);
50
51	/* See xen_irq_enable() for why preemption must be disabled. */
52	preempt_disable();
53	vcpu = this_cpu_read(xen_vcpu);
54	vcpu->evtchn_upcall_mask = flags;
55
56	if (flags == 0) {
57		barrier(); /* unmask then check (avoid races) */
58		if (unlikely(vcpu->evtchn_upcall_pending))
59			xen_force_evtchn_callback();
60		preempt_enable();
61	} else
62		preempt_enable_no_resched();
63}
64PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl);
65
66asmlinkage __visible void xen_irq_disable(void)
67{
68	/* There's a one instruction preempt window here.  We need to
69	   make sure we're don't switch CPUs between getting the vcpu
70	   pointer and updating the mask. */
71	preempt_disable();
72	this_cpu_read(xen_vcpu)->evtchn_upcall_mask = 1;
73	preempt_enable_no_resched();
74}
75PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable);
76
77asmlinkage __visible void xen_irq_enable(void)
78{
79	struct vcpu_info *vcpu;
80
81	/*
82	 * We may be preempted as soon as vcpu->evtchn_upcall_mask is
83	 * cleared, so disable preemption to ensure we check for
84	 * events on the VCPU we are still running on.
85	 */
86	preempt_disable();
87
88	vcpu = this_cpu_read(xen_vcpu);
89	vcpu->evtchn_upcall_mask = 0;
90
91	/* Doesn't matter if we get preempted here, because any
92	   pending event will get dealt with anyway. */
93
94	barrier(); /* unmask then check (avoid races) */
95	if (unlikely(vcpu->evtchn_upcall_pending))
96		xen_force_evtchn_callback();
97
98	preempt_enable();
99}
100PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable);
101
102static void xen_safe_halt(void)
103{
104	/* Blocking includes an implicit local_irq_enable(). */
105	if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
106		BUG();
107}
108
109static void xen_halt(void)
110{
111	if (irqs_disabled())
112		HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
113	else
114		xen_safe_halt();
115}
116
117static const struct pv_irq_ops xen_irq_ops __initconst = {
118	.save_fl = PV_CALLEE_SAVE(xen_save_fl),
119	.restore_fl = PV_CALLEE_SAVE(xen_restore_fl),
120	.irq_disable = PV_CALLEE_SAVE(xen_irq_disable),
121	.irq_enable = PV_CALLEE_SAVE(xen_irq_enable),
122
123	.safe_halt = xen_safe_halt,
124	.halt = xen_halt,
125#ifdef CONFIG_X86_64
126	.adjust_exception_frame = xen_adjust_exception_frame,
127#endif
128};
129
130void __init xen_init_irq_ops(void)
131{
132	/* For PVH we use default pv_irq_ops settings. */
133	if (!xen_feature(XENFEAT_hvm_callback_vector))
134		pv_irq_ops = xen_irq_ops;
135	x86_init.irqs.intr_init = xen_init_IRQ;
136}
137