xref: /linux/tools/virtio/ringtest/main.h (revision 905e46acd3272d04566fec49afbd7ad9e2ed9ae3)
1 /*
2  * Copyright (C) 2016 Red Hat, Inc.
3  * Author: Michael S. Tsirkin <mst@redhat.com>
4  * This work is licensed under the terms of the GNU GPL, version 2.
5  *
6  * Common macros and functions for ring benchmarking.
7  */
8 #ifndef MAIN_H
9 #define MAIN_H
10 
11 #include <stdbool.h>
12 
13 extern int param;
14 
15 extern bool do_exit;
16 
17 #if defined(__x86_64__) || defined(__i386__)
18 #include "x86intrin.h"
19 
20 static inline void wait_cycles(unsigned long long cycles)
21 {
22 	unsigned long long t;
23 
24 	t = __rdtsc();
25 	while (__rdtsc() - t < cycles) {}
26 }
27 
28 #define VMEXIT_CYCLES 500
29 #define VMENTRY_CYCLES 500
30 
31 #elif defined(__s390x__)
32 static inline void wait_cycles(unsigned long long cycles)
33 {
34 	asm volatile("0: brctg %0,0b" : : "d" (cycles));
35 }
36 
37 /* tweak me */
38 #define VMEXIT_CYCLES 200
39 #define VMENTRY_CYCLES 200
40 
41 #else
42 static inline void wait_cycles(unsigned long long cycles)
43 {
44 	_Exit(5);
45 }
46 #define VMEXIT_CYCLES 0
47 #define VMENTRY_CYCLES 0
48 #endif
49 
50 static inline void vmexit(void)
51 {
52 	if (!do_exit)
53 		return;
54 
55 	wait_cycles(VMEXIT_CYCLES);
56 }
57 static inline void vmentry(void)
58 {
59 	if (!do_exit)
60 		return;
61 
62 	wait_cycles(VMENTRY_CYCLES);
63 }
64 
65 /* implemented by ring */
66 void alloc_ring(void);
67 /* guest side */
68 int add_inbuf(unsigned, void *, void *);
69 void *get_buf(unsigned *, void **);
70 void disable_call();
71 bool used_empty();
72 bool enable_call();
73 void kick_available();
74 /* host side */
75 void disable_kick();
76 bool avail_empty();
77 bool enable_kick();
78 bool use_buf(unsigned *, void **);
79 void call_used();
80 
81 /* implemented by main */
82 extern bool do_sleep;
83 void kick(void);
84 void wait_for_kick(void);
85 void call(void);
86 void wait_for_call(void);
87 
88 extern unsigned ring_size;
89 
90 /* Compiler barrier - similar to what Linux uses */
91 #define barrier() asm volatile("" ::: "memory")
92 
93 /* Is there a portable way to do this? */
94 #if defined(__x86_64__) || defined(__i386__)
95 #define cpu_relax() asm ("rep; nop" ::: "memory")
96 #elif defined(__s390x__)
97 #define cpu_relax() barrier()
98 #else
99 #define cpu_relax() assert(0)
100 #endif
101 
102 extern bool do_relax;
103 
104 static inline void busy_wait(void)
105 {
106 	if (do_relax)
107 		cpu_relax();
108 	else
109 		/* prevent compiler from removing busy loops */
110 		barrier();
111 }
112 
113 /*
114  * Not using __ATOMIC_SEQ_CST since gcc docs say they are only synchronized
115  * with other __ATOMIC_SEQ_CST calls.
116  */
117 #define smp_mb() __sync_synchronize()
118 
119 /*
120  * This abuses the atomic builtins for thread fences, and
121  * adds a compiler barrier.
122  */
123 #define smp_release() do { \
124     barrier(); \
125     __atomic_thread_fence(__ATOMIC_RELEASE); \
126 } while (0)
127 
128 #define smp_acquire() do { \
129     __atomic_thread_fence(__ATOMIC_ACQUIRE); \
130     barrier(); \
131 } while (0)
132 
133 #endif
134