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