Commit | Line | Data |
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5ead97c8 JF |
1 | /* |
2 | * Xen hypercall batching. | |
3 | * | |
4 | * Xen allows multiple hypercalls to be issued at once, using the | |
5 | * multicall interface. This allows the cost of trapping into the | |
6 | * hypervisor to be amortized over several calls. | |
7 | * | |
8 | * This file implements a simple interface for multicalls. There's a | |
9 | * per-cpu buffer of outstanding multicalls. When you want to queue a | |
10 | * multicall for issuing, you can allocate a multicall slot for the | |
11 | * call and its arguments, along with storage for space which is | |
12 | * pointed to by the arguments (for passing pointers to structures, | |
13 | * etc). When the multicall is actually issued, all the space for the | |
14 | * commands and allocated memory is freed for reuse. | |
15 | * | |
16 | * Multicalls are flushed whenever any of the buffers get full, or | |
17 | * when explicitly requested. There's no way to get per-multicall | |
18 | * return results back. It will BUG if any of the multicalls fail. | |
19 | * | |
20 | * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007 | |
21 | */ | |
22 | #include <linux/percpu.h> | |
f120f13e | 23 | #include <linux/hardirq.h> |
994025ca | 24 | #include <linux/debugfs.h> |
5ead97c8 JF |
25 | |
26 | #include <asm/xen/hypercall.h> | |
27 | ||
28 | #include "multicalls.h" | |
994025ca JF |
29 | #include "debugfs.h" |
30 | ||
31 | #define MC_BATCH 32 | |
5ead97c8 | 32 | |
ffc78767 | 33 | #define MC_DEBUG 0 |
a122d623 | 34 | |
400d3494 | 35 | #define MC_ARGS (MC_BATCH * 16) |
5ead97c8 | 36 | |
994025ca | 37 | |
5ead97c8 | 38 | struct mc_buffer { |
2a6f6d09 | 39 | unsigned mcidx, argidx, cbidx; |
5ead97c8 | 40 | struct multicall_entry entries[MC_BATCH]; |
a122d623 JF |
41 | #if MC_DEBUG |
42 | struct multicall_entry debug[MC_BATCH]; | |
b93d51dc | 43 | void *caller[MC_BATCH]; |
a122d623 | 44 | #endif |
400d3494 | 45 | unsigned char args[MC_ARGS]; |
91e0c5f3 JF |
46 | struct callback { |
47 | void (*fn)(void *); | |
48 | void *data; | |
49 | } callbacks[MC_BATCH]; | |
5ead97c8 JF |
50 | }; |
51 | ||
52 | static DEFINE_PER_CPU(struct mc_buffer, mc_buffer); | |
53 | DEFINE_PER_CPU(unsigned long, xen_mc_irq_flags); | |
54 | ||
55 | void xen_mc_flush(void) | |
56 | { | |
89cbc767 | 57 | struct mc_buffer *b = this_cpu_ptr(&mc_buffer); |
eac303bf | 58 | struct multicall_entry *mc; |
5ead97c8 JF |
59 | int ret = 0; |
60 | unsigned long flags; | |
91e0c5f3 | 61 | int i; |
5ead97c8 | 62 | |
f120f13e JF |
63 | BUG_ON(preemptible()); |
64 | ||
5ead97c8 JF |
65 | /* Disable interrupts in case someone comes in and queues |
66 | something in the middle */ | |
67 | local_irq_save(flags); | |
68 | ||
c796f213 JF |
69 | trace_xen_mc_flush(b->mcidx, b->argidx, b->cbidx); |
70 | ||
eac303bf JF |
71 | switch (b->mcidx) { |
72 | case 0: | |
73 | /* no-op */ | |
74 | BUG_ON(b->argidx != 0); | |
75 | break; | |
76 | ||
77 | case 1: | |
78 | /* Singleton multicall - bypass multicall machinery | |
79 | and just do the call directly. */ | |
80 | mc = &b->entries[0]; | |
81 | ||
82 | mc->result = privcmd_call(mc->op, | |
83 | mc->args[0], mc->args[1], mc->args[2], | |
84 | mc->args[3], mc->args[4]); | |
85 | ret = mc->result < 0; | |
86 | break; | |
87 | ||
88 | default: | |
a122d623 JF |
89 | #if MC_DEBUG |
90 | memcpy(b->debug, b->entries, | |
91 | b->mcidx * sizeof(struct multicall_entry)); | |
92 | #endif | |
93 | ||
5ead97c8 JF |
94 | if (HYPERVISOR_multicall(b->entries, b->mcidx) != 0) |
95 | BUG(); | |
96 | for (i = 0; i < b->mcidx; i++) | |
97 | if (b->entries[i].result < 0) | |
98 | ret++; | |
a122d623 JF |
99 | |
100 | #if MC_DEBUG | |
101 | if (ret) { | |
102 | printk(KERN_ERR "%d multicall(s) failed: cpu %d\n", | |
103 | ret, smp_processor_id()); | |
8ba6c2b0 | 104 | dump_stack(); |
7ebed39f | 105 | for (i = 0; i < b->mcidx; i++) { |
b93d51dc | 106 | printk(KERN_DEBUG " call %2d/%d: op=%lu arg=[%lx] result=%ld\t%pF\n", |
a122d623 JF |
107 | i+1, b->mcidx, |
108 | b->debug[i].op, | |
109 | b->debug[i].args[0], | |
b93d51dc IC |
110 | b->entries[i].result, |
111 | b->caller[i]); | |
a122d623 JF |
112 | } |
113 | } | |
114 | #endif | |
eac303bf | 115 | } |
a122d623 | 116 | |
eac303bf JF |
117 | b->mcidx = 0; |
118 | b->argidx = 0; | |
5ead97c8 | 119 | |
7ebed39f | 120 | for (i = 0; i < b->cbidx; i++) { |
91e0c5f3 JF |
121 | struct callback *cb = &b->callbacks[i]; |
122 | ||
123 | (*cb->fn)(cb->data); | |
124 | } | |
125 | b->cbidx = 0; | |
126 | ||
c9960863 JF |
127 | local_irq_restore(flags); |
128 | ||
3d39e9d0 | 129 | WARN_ON(ret); |
5ead97c8 JF |
130 | } |
131 | ||
132 | struct multicall_space __xen_mc_entry(size_t args) | |
133 | { | |
89cbc767 | 134 | struct mc_buffer *b = this_cpu_ptr(&mc_buffer); |
5ead97c8 | 135 | struct multicall_space ret; |
400d3494 | 136 | unsigned argidx = roundup(b->argidx, sizeof(u64)); |
5ead97c8 | 137 | |
c796f213 JF |
138 | trace_xen_mc_entry_alloc(args); |
139 | ||
f120f13e | 140 | BUG_ON(preemptible()); |
f124c6ae | 141 | BUG_ON(b->argidx >= MC_ARGS); |
5ead97c8 | 142 | |
4a7b005d JF |
143 | if (unlikely(b->mcidx == MC_BATCH || |
144 | (argidx + args) >= MC_ARGS)) { | |
c796f213 JF |
145 | trace_xen_mc_flush_reason((b->mcidx == MC_BATCH) ? |
146 | XEN_MC_FL_BATCH : XEN_MC_FL_ARGS); | |
5ead97c8 | 147 | xen_mc_flush(); |
400d3494 JF |
148 | argidx = roundup(b->argidx, sizeof(u64)); |
149 | } | |
5ead97c8 JF |
150 | |
151 | ret.mc = &b->entries[b->mcidx]; | |
ffc78767 | 152 | #if MC_DEBUG |
b93d51dc IC |
153 | b->caller[b->mcidx] = __builtin_return_address(0); |
154 | #endif | |
5ead97c8 | 155 | b->mcidx++; |
400d3494 JF |
156 | ret.args = &b->args[argidx]; |
157 | b->argidx = argidx + args; | |
158 | ||
f124c6ae | 159 | BUG_ON(b->argidx >= MC_ARGS); |
400d3494 JF |
160 | return ret; |
161 | } | |
162 | ||
163 | struct multicall_space xen_mc_extend_args(unsigned long op, size_t size) | |
164 | { | |
89cbc767 | 165 | struct mc_buffer *b = this_cpu_ptr(&mc_buffer); |
400d3494 JF |
166 | struct multicall_space ret = { NULL, NULL }; |
167 | ||
168 | BUG_ON(preemptible()); | |
f124c6ae | 169 | BUG_ON(b->argidx >= MC_ARGS); |
400d3494 | 170 | |
c796f213 JF |
171 | if (unlikely(b->mcidx == 0 || |
172 | b->entries[b->mcidx - 1].op != op)) { | |
173 | trace_xen_mc_extend_args(op, size, XEN_MC_XE_BAD_OP); | |
174 | goto out; | |
175 | } | |
400d3494 | 176 | |
c796f213 JF |
177 | if (unlikely((b->argidx + size) >= MC_ARGS)) { |
178 | trace_xen_mc_extend_args(op, size, XEN_MC_XE_NO_SPACE); | |
179 | goto out; | |
180 | } | |
400d3494 JF |
181 | |
182 | ret.mc = &b->entries[b->mcidx - 1]; | |
5ead97c8 | 183 | ret.args = &b->args[b->argidx]; |
400d3494 | 184 | b->argidx += size; |
5ead97c8 | 185 | |
f124c6ae | 186 | BUG_ON(b->argidx >= MC_ARGS); |
c796f213 JF |
187 | |
188 | trace_xen_mc_extend_args(op, size, XEN_MC_XE_OK); | |
189 | out: | |
5ead97c8 JF |
190 | return ret; |
191 | } | |
91e0c5f3 JF |
192 | |
193 | void xen_mc_callback(void (*fn)(void *), void *data) | |
194 | { | |
89cbc767 | 195 | struct mc_buffer *b = this_cpu_ptr(&mc_buffer); |
91e0c5f3 JF |
196 | struct callback *cb; |
197 | ||
c796f213 JF |
198 | if (b->cbidx == MC_BATCH) { |
199 | trace_xen_mc_flush_reason(XEN_MC_FL_CALLBACK); | |
91e0c5f3 | 200 | xen_mc_flush(); |
c796f213 JF |
201 | } |
202 | ||
203 | trace_xen_mc_callback(fn, data); | |
91e0c5f3 JF |
204 | |
205 | cb = &b->callbacks[b->cbidx++]; | |
206 | cb->fn = fn; | |
207 | cb->data = data; | |
208 | } |