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 
36 static DEFINE_STATIC_KEY_FALSE(has_movntdqa);
37 
__memcpy_ntdqa(void * dst,const void * src,unsigned long len)38 static 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 
__memcpy_ntdqu(void * dst,const void * src,unsigned long len)67 static 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  */
i915_memcpy_from_wc(void * dst,const void * src,unsigned long len)113 bool 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 >> 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  */
i915_unaligned_memcpy_from_wc(void * dst,const void * src,unsigned long len)138 void 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 
i915_memcpy_init_early(struct drm_i915_private * dev_priv)159 void 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