1/*
2 * Copyright © 2016 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 *
23 */
24
25#include <linux/kernel.h>
26#include <asm/fpu/api.h>
27
28#include "i915_memcpy.h"
29
30#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
31#define CI_BUG_ON(expr) BUG_ON(expr)
32#else
33#define CI_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
34#endif
35
36static DEFINE_STATIC_KEY_FALSE(has_movntdqa);
37
38static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len)
39{
40 kernel_fpu_begin();
41
42 while (len >= 4) {
43 asm("movntdqa (%0), %%xmm0\n"
44 "movntdqa 16(%0), %%xmm1\n"
45 "movntdqa 32(%0), %%xmm2\n"
46 "movntdqa 48(%0), %%xmm3\n"
47 "movaps %%xmm0, (%1)\n"
48 "movaps %%xmm1, 16(%1)\n"
49 "movaps %%xmm2, 32(%1)\n"
50 "movaps %%xmm3, 48(%1)\n"
51 :: "r" (src), "r" (dst) : "memory");
52 src += 64;
53 dst += 64;
54 len -= 4;
55 }
56 while (len--) {
57 asm("movntdqa (%0), %%xmm0\n"
58 "movaps %%xmm0, (%1)\n"
59 :: "r" (src), "r" (dst) : "memory");
60 src += 16;
61 dst += 16;
62 }
63
64 kernel_fpu_end();
65}
66
67static void __memcpy_ntdqu(void *dst, const void *src, unsigned long len)
68{
69 kernel_fpu_begin();
70
71 while (len >= 4) {
72 asm("movntdqa (%0), %%xmm0\n"
73 "movntdqa 16(%0), %%xmm1\n"
74 "movntdqa 32(%0), %%xmm2\n"
75 "movntdqa 48(%0), %%xmm3\n"
76 "movups %%xmm0, (%1)\n"
77 "movups %%xmm1, 16(%1)\n"
78 "movups %%xmm2, 32(%1)\n"
79 "movups %%xmm3, 48(%1)\n"
80 :: "r" (src), "r" (dst) : "memory");
81 src += 64;
82 dst += 64;
83 len -= 4;
84 }
85 while (len--) {
86 asm("movntdqa (%0), %%xmm0\n"
87 "movups %%xmm0, (%1)\n"
88 :: "r" (src), "r" (dst) : "memory");
89 src += 16;
90 dst += 16;
91 }
92
93 kernel_fpu_end();
94}
95
96/**
97 * i915_memcpy_from_wc: perform an accelerated *aligned* read from WC
98 * @dst: destination pointer
99 * @src: source pointer
100 * @len: how many bytes to copy
101 *
102 * i915_memcpy_from_wc copies @len bytes from @src to @dst using
103 * non-temporal instructions where available. Note that all arguments
104 * (@src, @dst) must be aligned to 16 bytes and @len must be a multiple
105 * of 16.
106 *
107 * To test whether accelerated reads from WC are supported, use
108 * i915_memcpy_from_wc(NULL, NULL, 0);
109 *
110 * Returns true if the copy was successful, false if the preconditions
111 * are not met.
112 */
113bool i915_memcpy_from_wc(void *dst, const void *src, unsigned long len)
114{
115 if (unlikely(((unsigned long)dst | (unsigned long)src | len) & 15))
116 return false;
117
118 if (static_branch_likely(&has_movntdqa)) {
119 if (likely(len))
120 __memcpy_ntdqa(dst, src, len: len >> 4);
121 return true;
122 }
123
124 return false;
125}
126
127/**
128 * i915_unaligned_memcpy_from_wc: perform a mostly accelerated read from WC
129 * @dst: destination pointer
130 * @src: source pointer
131 * @len: how many bytes to copy
132 *
133 * Like i915_memcpy_from_wc(), the unaligned variant copies @len bytes from
134 * @src to @dst using * non-temporal instructions where available, but
135 * accepts that its arguments may not be aligned, but are valid for the
136 * potential 16-byte read past the end.
137 */
138void i915_unaligned_memcpy_from_wc(void *dst, const void *src, unsigned long len)
139{
140 unsigned long addr;
141
142 CI_BUG_ON(!i915_has_memcpy_from_wc());
143
144 addr = (unsigned long)src;
145 if (!IS_ALIGNED(addr, 16)) {
146 unsigned long x = min(ALIGN(addr, 16) - addr, len);
147
148 memcpy(dst, src, x);
149
150 len -= x;
151 dst += x;
152 src += x;
153 }
154
155 if (likely(len))
156 __memcpy_ntdqu(dst, src, DIV_ROUND_UP(len, 16));
157}
158
159void i915_memcpy_init_early(struct drm_i915_private *dev_priv)
160{
161 /*
162 * Some hypervisors (e.g. KVM) don't support VEX-prefix instructions
163 * emulation. So don't enable movntdqa in hypervisor guest.
164 */
165 if (static_cpu_has(X86_FEATURE_XMM4_1) &&
166 !boot_cpu_has(X86_FEATURE_HYPERVISOR))
167 static_branch_enable(&has_movntdqa);
168}
169

source code of linux/drivers/gpu/drm/i915/i915_memcpy.c