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Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -07001#include <linux/hardirq.h>
2
Thomas Gleixner66bcaf02009-08-20 09:59:09 +02003#include <asm/x86_init.h>
4
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -07005#include <xen/interface/xen.h>
6#include <xen/interface/sched.h>
7#include <xen/interface/vcpu.h>
8
9#include <asm/xen/hypercall.h>
10#include <asm/xen/hypervisor.h>
11
12#include "xen-ops.h"
13
14/*
15 * Force a proper event-channel callback from Xen after clearing the
16 * callback mask. We do this in a very simple manner, by making a call
17 * down into Xen. The pending flag will be checked by Xen on return.
18 */
19void xen_force_evtchn_callback(void)
20{
21 (void)HYPERVISOR_xen_version(0, NULL);
22}
23
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -070024static unsigned long xen_save_fl(void)
25{
26 struct vcpu_info *vcpu;
27 unsigned long flags;
28
Ingo Molnar6dbde352009-01-15 22:15:53 +090029 vcpu = percpu_read(xen_vcpu);
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -070030
31 /* flag has opposite sense of mask */
32 flags = !vcpu->evtchn_upcall_mask;
33
34 /* convert to IF type flag
35 -0 -> 0x00000000
36 -1 -> 0xffffffff
37 */
38 return (-flags) & X86_EFLAGS_IF;
39}
Jeremy Fitzhardingeecb93d12009-01-28 14:35:05 -080040PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl);
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -070041
42static void xen_restore_fl(unsigned long flags)
43{
44 struct vcpu_info *vcpu;
45
46 /* convert from IF type flag */
47 flags = !(flags & X86_EFLAGS_IF);
48
49 /* There's a one instruction preempt window here. We need to
50 make sure we're don't switch CPUs between getting the vcpu
51 pointer and updating the mask. */
52 preempt_disable();
Ingo Molnar6dbde352009-01-15 22:15:53 +090053 vcpu = percpu_read(xen_vcpu);
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -070054 vcpu->evtchn_upcall_mask = flags;
55 preempt_enable_no_resched();
56
57 /* Doesn't matter if we get preempted here, because any
58 pending event will get dealt with anyway. */
59
60 if (flags == 0) {
61 preempt_check_resched();
62 barrier(); /* unmask then check (avoid races) */
63 if (unlikely(vcpu->evtchn_upcall_pending))
64 xen_force_evtchn_callback();
65 }
66}
Jeremy Fitzhardingeecb93d12009-01-28 14:35:05 -080067PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl);
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -070068
69static void xen_irq_disable(void)
70{
71 /* There's a one instruction preempt window here. We need to
72 make sure we're don't switch CPUs between getting the vcpu
73 pointer and updating the mask. */
74 preempt_disable();
Ingo Molnar6dbde352009-01-15 22:15:53 +090075 percpu_read(xen_vcpu)->evtchn_upcall_mask = 1;
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -070076 preempt_enable_no_resched();
77}
Jeremy Fitzhardingeecb93d12009-01-28 14:35:05 -080078PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable);
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -070079
80static void xen_irq_enable(void)
81{
82 struct vcpu_info *vcpu;
83
84 /* We don't need to worry about being preempted here, since
85 either a) interrupts are disabled, so no preemption, or b)
86 the caller is confused and is trying to re-enable interrupts
87 on an indeterminate processor. */
88
Ingo Molnar6dbde352009-01-15 22:15:53 +090089 vcpu = percpu_read(xen_vcpu);
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -070090 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}
Jeremy Fitzhardingeecb93d12009-01-28 14:35:05 -080099PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable);
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -0700100
101static void xen_safe_halt(void)
102{
103 /* Blocking includes an implicit local_irq_enable(). */
104 if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
105 BUG();
106}
107
108static void xen_halt(void)
109{
110 if (irqs_disabled())
111 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
112 else
113 xen_safe_halt();
114}
115
Daniel Kiper251511a2011-05-04 20:16:07 +0200116static const struct pv_irq_ops xen_irq_ops __initconst = {
Jeremy Fitzhardingeecb93d12009-01-28 14:35:05 -0800117 .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
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -0700122 .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
Randy Dunlap7d81c3b2011-01-08 20:00:36 -0800129void __init xen_init_irq_ops(void)
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -0700130{
131 pv_irq_ops = xen_irq_ops;
Thomas Gleixner66bcaf02009-08-20 09:59:09 +0200132 x86_init.irqs.intr_init = xen_init_IRQ;
Jeremy Fitzhardinge0d1edf42008-07-28 11:53:57 -0700133}