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0d1edf46 JF |
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 | */ | |
17 | void xen_force_evtchn_callback(void) | |
18 | { | |
19 | (void)HYPERVISOR_xen_version(0, NULL); | |
20 | } | |
21 | ||
0d1edf46 JF |
22 | static unsigned long xen_save_fl(void) |
23 | { | |
24 | struct vcpu_info *vcpu; | |
25 | unsigned long flags; | |
26 | ||
6dbde353 | 27 | vcpu = percpu_read(xen_vcpu); |
0d1edf46 JF |
28 | |
29 | /* flag has opposite sense of mask */ | |
30 | flags = !vcpu->evtchn_upcall_mask; | |
31 | ||
32 | /* convert to IF type flag | |
33 | -0 -> 0x00000000 | |
34 | -1 -> 0xffffffff | |
35 | */ | |
36 | return (-flags) & X86_EFLAGS_IF; | |
37 | } | |
ecb93d1c | 38 | PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl); |
0d1edf46 JF |
39 | |
40 | static void xen_restore_fl(unsigned long flags) | |
41 | { | |
42 | struct vcpu_info *vcpu; | |
43 | ||
44 | /* convert from IF type flag */ | |
45 | flags = !(flags & X86_EFLAGS_IF); | |
46 | ||
47 | /* There's a one instruction preempt window here. We need to | |
48 | make sure we're don't switch CPUs between getting the vcpu | |
49 | pointer and updating the mask. */ | |
50 | preempt_disable(); | |
6dbde353 | 51 | vcpu = percpu_read(xen_vcpu); |
0d1edf46 JF |
52 | vcpu->evtchn_upcall_mask = flags; |
53 | preempt_enable_no_resched(); | |
54 | ||
55 | /* Doesn't matter if we get preempted here, because any | |
56 | pending event will get dealt with anyway. */ | |
57 | ||
58 | if (flags == 0) { | |
59 | preempt_check_resched(); | |
60 | barrier(); /* unmask then check (avoid races) */ | |
61 | if (unlikely(vcpu->evtchn_upcall_pending)) | |
62 | xen_force_evtchn_callback(); | |
63 | } | |
64 | } | |
ecb93d1c | 65 | PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl); |
0d1edf46 JF |
66 | |
67 | static 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(); | |
6dbde353 | 73 | percpu_read(xen_vcpu)->evtchn_upcall_mask = 1; |
0d1edf46 JF |
74 | preempt_enable_no_resched(); |
75 | } | |
ecb93d1c | 76 | PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable); |
0d1edf46 JF |
77 | |
78 | static void xen_irq_enable(void) | |
79 | { | |
80 | struct vcpu_info *vcpu; | |
81 | ||
82 | /* We don't need to worry about being preempted here, since | |
83 | either a) interrupts are disabled, so no preemption, or b) | |
84 | the caller is confused and is trying to re-enable interrupts | |
85 | on an indeterminate processor. */ | |
86 | ||
6dbde353 | 87 | vcpu = percpu_read(xen_vcpu); |
0d1edf46 JF |
88 | vcpu->evtchn_upcall_mask = 0; |
89 | ||
90 | /* Doesn't matter if we get preempted here, because any | |
91 | pending event will get dealt with anyway. */ | |
92 | ||
93 | barrier(); /* unmask then check (avoid races) */ | |
94 | if (unlikely(vcpu->evtchn_upcall_pending)) | |
95 | xen_force_evtchn_callback(); | |
96 | } | |
ecb93d1c | 97 | PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable); |
0d1edf46 JF |
98 | |
99 | static void xen_safe_halt(void) | |
100 | { | |
101 | /* Blocking includes an implicit local_irq_enable(). */ | |
102 | if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0) | |
103 | BUG(); | |
104 | } | |
105 | ||
106 | static void xen_halt(void) | |
107 | { | |
108 | if (irqs_disabled()) | |
109 | HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); | |
110 | else | |
111 | xen_safe_halt(); | |
112 | } | |
113 | ||
114 | static const struct pv_irq_ops xen_irq_ops __initdata = { | |
792dc4f6 | 115 | .init_IRQ = xen_init_IRQ, |
ecb93d1c JF |
116 | |
117 | .save_fl = PV_CALLEE_SAVE(xen_save_fl), | |
118 | .restore_fl = PV_CALLEE_SAVE(xen_restore_fl), | |
119 | .irq_disable = PV_CALLEE_SAVE(xen_irq_disable), | |
120 | .irq_enable = PV_CALLEE_SAVE(xen_irq_enable), | |
121 | ||
0d1edf46 JF |
122 | .safe_halt = xen_safe_halt, |
123 | .halt = xen_halt, | |
124 | #ifdef CONFIG_X86_64 | |
125 | .adjust_exception_frame = xen_adjust_exception_frame, | |
126 | #endif | |
127 | }; | |
128 | ||
129 | void __init xen_init_irq_ops() | |
130 | { | |
131 | pv_irq_ops = xen_irq_ops; | |
132 | } |