1 #include <linux/hardirq.h>
2
3 #include <xen/interface/xen.h>
4 #include <xen/interface/sched.h>
5 #include <xen/interface/vcpu.h>
6
7 #include <asm/xen/hypercall.h>
8 #include <asm/xen/hypervisor.h>
9
10 #include "xen-ops.h"
11
12 /*
13 * Force a proper event-channel callback from Xen after clearing the
14 * callback mask. We do this in a very simple manner, by making a call
15 * down into Xen. The pending flag will be checked by Xen on return.
16 */
xen_force_evtchn_callback(void)17 void xen_force_evtchn_callback(void)
18 {
19 (void)HYPERVISOR_xen_version(0, NULL);
20 }
21
__xen_init_IRQ(void)22 static void __init __xen_init_IRQ(void)
23 {
24 int i;
25
26 /* Create identity vector->irq map */
27 for(i = 0; i < NR_VECTORS; i++) {
28 int cpu;
29
30 for_each_possible_cpu(cpu)
31 per_cpu(vector_irq, cpu)[i] = i;
32 }
33
34 xen_init_IRQ();
35 }
36
xen_save_fl(void)37 static unsigned long xen_save_fl(void)
38 {
39 struct vcpu_info *vcpu;
40 unsigned long flags;
41
42 vcpu = x86_read_percpu(xen_vcpu);
43
44 /* flag has opposite sense of mask */
45 flags = !vcpu->evtchn_upcall_mask;
46
47 /* convert to IF type flag
48 -0 -> 0x00000000
49 -1 -> 0xffffffff
50 */
51 return (-flags) & X86_EFLAGS_IF;
52 }
53
xen_restore_fl(unsigned long flags)54 static void xen_restore_fl(unsigned long flags)
55 {
56 struct vcpu_info *vcpu;
57
58 /* convert from IF type flag */
59 flags = !(flags & X86_EFLAGS_IF);
60
61 /* There's a one instruction preempt window here. We need to
62 make sure we're don't switch CPUs between getting the vcpu
63 pointer and updating the mask. */
64 preempt_disable();
65 vcpu = x86_read_percpu(xen_vcpu);
66 vcpu->evtchn_upcall_mask = flags;
67 preempt_enable_no_resched();
68
69 /* Doesn't matter if we get preempted here, because any
70 pending event will get dealt with anyway. */
71
72 if (flags == 0) {
73 preempt_check_resched();
74 barrier(); /* unmask then check (avoid races) */
75 if (unlikely(vcpu->evtchn_upcall_pending))
76 xen_force_evtchn_callback();
77 }
78 }
79
xen_irq_disable(void)80 static void xen_irq_disable(void)
81 {
82 /* There's a one instruction preempt window here. We need to
83 make sure we're don't switch CPUs between getting the vcpu
84 pointer and updating the mask. */
85 preempt_disable();
86 x86_read_percpu(xen_vcpu)->evtchn_upcall_mask = 1;
87 preempt_enable_no_resched();
88 }
89
xen_irq_enable(void)90 static void xen_irq_enable(void)
91 {
92 struct vcpu_info *vcpu;
93
94 /* We don't need to worry about being preempted here, since
95 either a) interrupts are disabled, so no preemption, or b)
96 the caller is confused and is trying to re-enable interrupts
97 on an indeterminate processor. */
98
99 vcpu = x86_read_percpu(xen_vcpu);
100 vcpu->evtchn_upcall_mask = 0;
101
102 /* Doesn't matter if we get preempted here, because any
103 pending event will get dealt with anyway. */
104
105 barrier(); /* unmask then check (avoid races) */
106 if (unlikely(vcpu->evtchn_upcall_pending))
107 xen_force_evtchn_callback();
108 }
109
xen_safe_halt(void)110 static void xen_safe_halt(void)
111 {
112 /* Blocking includes an implicit local_irq_enable(). */
113 if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
114 BUG();
115 }
116
xen_halt(void)117 static void xen_halt(void)
118 {
119 if (irqs_disabled())
120 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
121 else
122 xen_safe_halt();
123 }
124
125 static const struct pv_irq_ops xen_irq_ops __initdata = {
126 .init_IRQ = __xen_init_IRQ,
127 .save_fl = xen_save_fl,
128 .restore_fl = xen_restore_fl,
129 .irq_disable = xen_irq_disable,
130 .irq_enable = xen_irq_enable,
131 .safe_halt = xen_safe_halt,
132 .halt = xen_halt,
133 #ifdef CONFIG_X86_64
134 .adjust_exception_frame = xen_adjust_exception_frame,
135 #endif
136 };
137
xen_init_irq_ops()138 void __init xen_init_irq_ops()
139 {
140 pv_irq_ops = xen_irq_ops;
141 }
142