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 #ifdef CONFIG_AS_MOVNTDQA
  39 static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len)
  40 {
  41         kernel_fpu_begin();
  42
  43         while (len >= 4) {
  44                 asm("movntdqa   (%0), %%xmm0\n"
  45                     "movntdqa 16(%0), %%xmm1\n"
  46                     "movntdqa 32(%0), %%xmm2\n"
  47                     "movntdqa 48(%0), %%xmm3\n"
  48                     "movaps %%xmm0,   (%1)\n"
  49                     "movaps %%xmm1, 16(%1)\n"
  50                     "movaps %%xmm2, 32(%1)\n"
  51                     "movaps %%xmm3, 48(%1)\n"
  52                     :: "r" (src), "r" (dst) : "memory");
  53                 src += 64;
  54                 dst += 64;
  55                 len -= 4;
  56         }
  57         while (len--) {
  58                 asm("movntdqa (%0), %%xmm0\n"
  59                     "movaps %%xmm0, (%1)\n"
  60                     :: "r" (src), "r" (dst) : "memory");
  61                 src += 16;
  62                 dst += 16;
  63         }
  64
  65         kernel_fpu_end();
  66 }
  67
  68 static void __memcpy_ntdqu(void *dst, const void *src, unsigned long len)
  69 {
  70         kernel_fpu_begin();
  71
  72         while (len >= 4) {
  73                 asm("movntdqa   (%0), %%xmm0\n"
  74                     "movntdqa 16(%0), %%xmm1\n"
  75                     "movntdqa 32(%0), %%xmm2\n"
  76                     "movntdqa 48(%0), %%xmm3\n"
  77                     "movups %%xmm0,   (%1)\n"
  78                     "movups %%xmm1, 16(%1)\n"
  79                     "movups %%xmm2, 32(%1)\n"
  80                     "movups %%xmm3, 48(%1)\n"
  81                     :: "r" (src), "r" (dst) : "memory");
  82                 src += 64;
  83                 dst += 64;
  84                 len -= 4;
  85         }
  86         while (len--) {
  87                 asm("movntdqa (%0), %%xmm0\n"
  88                     "movups %%xmm0, (%1)\n"
  89                     :: "r" (src), "r" (dst) : "memory");
  90                 src += 16;
  91                 dst += 16;
  92         }
  93
  94         kernel_fpu_end();
  95 }
  96 #else
  97 static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len) {}
  98 static void __memcpy_ntdqu(void *dst, const void *src, unsigned long len) {}
  99 #endif
 100
 101 /**
 102  * i915_memcpy_from_wc: perform an accelerated *aligned* read from WC
 103  * @dst: destination pointer
 104  * @src: source pointer
 105  * @len: how many bytes to copy
 106  *
 107  * i915_memcpy_from_wc copies @len bytes from @src to @dst using
 108  * non-temporal instructions where available. Note that all arguments
 109  * (@src, @dst) must be aligned to 16 bytes and @len must be a multiple
 110  * of 16.
 111  *
 112  * To test whether accelerated reads from WC are supported, use
 113  * i915_memcpy_from_wc(NULL, NULL, 0);
 114  *
 115  * Returns true if the copy was successful, false if the preconditions
 116  * are not met.
 117  */
 118 bool i915_memcpy_from_wc(void *dst, const void *src, unsigned long len)
 119 {
 120         if (unlikely(((unsigned long)dst | (unsigned long)src | len) & 15))
 121                 return false;
 122
 123         if (static_branch_likely(&has_movntdqa)) {
 124                 if (likely(len))
 125                         __memcpy_ntdqa(dst, src, len >> 4);
 126                 return true;
 127         }
 128
 129         return false;
 130 }
 131
 132 /**
 133  * i915_unaligned_memcpy_from_wc: perform a mostly accelerated read from WC
 134  * @dst: destination pointer
 135  * @src: source pointer
 136  * @len: how many bytes to copy
 137  *
 138  * Like i915_memcpy_from_wc(), the unaligned variant copies @len bytes from
 139  * @src to @dst using * non-temporal instructions where available, but
 140  * accepts that its arguments may not be aligned, but are valid for the
 141  * potential 16-byte read past the end.
 142  */
 143 void i915_unaligned_memcpy_from_wc(void *dst, void *src, unsigned long len)
 144 {
 145         unsigned long addr;
 146
 147         CI_BUG_ON(!i915_has_memcpy_from_wc());
 148
 149         addr = (unsigned long)src;
 150         if (!IS_ALIGNED(addr, 16)) {
 151                 unsigned long x = min(ALIGN(addr, 16) - addr, len);
 152
 153                 memcpy(dst, src, x);
 154
 155                 len -= x;
 156                 dst += x;
 157                 src += x;
 158         }
 159
 160         if (likely(len))
 161                 __memcpy_ntdqu(dst, src, DIV_ROUND_UP(len, 16));
 162 }
 163
 164 void i915_memcpy_init_early(struct drm_i915_private *dev_priv)
 165 {
 166         /*
 167          * Some hypervisors (e.g. KVM) don't support VEX-prefix instructions
 168          * emulation. So don't enable movntdqa in hypervisor guest.
 169          */
 170         if (static_cpu_has(X86_FEATURE_XMM4_1) &&
 171             !boot_cpu_has(X86_FEATURE_HYPERVISOR))
 172                 static_branch_enable(&has_movntdqa);
 173 }