drivers/gpu/drm/i915/i915_memcpy.c

   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
  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
  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  */
 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  */
 138 void i915_unaligned_memcpy_from_wc(void *dst, 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
 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 }