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 <linux/string.h>
 27#include <linux/cpufeature.h>
 28#include <linux/bug.h>
 29#include <linux/build_bug.h>
 30#include <asm/fpu/api.h>
 31
 32#include "i915_memcpy.h"
 33
 34#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 35#define CI_BUG_ON(expr) BUG_ON(expr)
 36#else
 37#define CI_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
 38#endif
 39
 40static DEFINE_STATIC_KEY_FALSE(has_movntdqa);
 41
 42static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len)
 43{
 44	kernel_fpu_begin();
 45
 46	while (len >= 4) {
 47		asm("movntdqa   (%0), %%xmm0\n"
 48		    "movntdqa 16(%0), %%xmm1\n"
 49		    "movntdqa 32(%0), %%xmm2\n"
 50		    "movntdqa 48(%0), %%xmm3\n"
 51		    "movaps %%xmm0,   (%1)\n"
 52		    "movaps %%xmm1, 16(%1)\n"
 53		    "movaps %%xmm2, 32(%1)\n"
 54		    "movaps %%xmm3, 48(%1)\n"
 55		    :: "r" (src), "r" (dst) : "memory");
 56		src += 64;
 57		dst += 64;
 58		len -= 4;
 59	}
 60	while (len--) {
 61		asm("movntdqa (%0), %%xmm0\n"
 62		    "movaps %%xmm0, (%1)\n"
 63		    :: "r" (src), "r" (dst) : "memory");
 64		src += 16;
 65		dst += 16;
 66	}
 67
 68	kernel_fpu_end();
 69}
 70
 71static void __memcpy_ntdqu(void *dst, const void *src, unsigned long len)
 72{
 73	kernel_fpu_begin();
 74
 75	while (len >= 4) {
 76		asm("movntdqa   (%0), %%xmm0\n"
 77		    "movntdqa 16(%0), %%xmm1\n"
 78		    "movntdqa 32(%0), %%xmm2\n"
 79		    "movntdqa 48(%0), %%xmm3\n"
 80		    "movups %%xmm0,   (%1)\n"
 81		    "movups %%xmm1, 16(%1)\n"
 82		    "movups %%xmm2, 32(%1)\n"
 83		    "movups %%xmm3, 48(%1)\n"
 84		    :: "r" (src), "r" (dst) : "memory");
 85		src += 64;
 86		dst += 64;
 87		len -= 4;
 88	}
 89	while (len--) {
 90		asm("movntdqa (%0), %%xmm0\n"
 91		    "movups %%xmm0, (%1)\n"
 92		    :: "r" (src), "r" (dst) : "memory");
 93		src += 16;
 94		dst += 16;
 95	}
 96
 97	kernel_fpu_end();
 98}
 99
100/**
101 * i915_memcpy_from_wc: perform an accelerated *aligned* read from WC
102 * @dst: destination pointer
103 * @src: source pointer
104 * @len: how many bytes to copy
105 *
106 * i915_memcpy_from_wc copies @len bytes from @src to @dst using
107 * non-temporal instructions where available. Note that all arguments
108 * (@src, @dst) must be aligned to 16 bytes and @len must be a multiple
109 * of 16.
110 *
111 * To test whether accelerated reads from WC are supported, use
112 * i915_memcpy_from_wc(NULL, NULL, 0);
113 *
114 * Returns true if the copy was successful, false if the preconditions
115 * are not met.
116 */
117bool i915_memcpy_from_wc(void *dst, const void *src, unsigned long len)
118{
119	if (unlikely(((unsigned long)dst | (unsigned long)src | len) & 15))
120		return false;
121
122	if (static_branch_likely(&has_movntdqa)) {
123		if (likely(len))
124			__memcpy_ntdqa(dst, src, len >> 4);
125		return true;
126	}
127
128	return false;
129}
130
131/**
132 * i915_unaligned_memcpy_from_wc: perform a mostly accelerated read from WC
133 * @dst: destination pointer
134 * @src: source pointer
135 * @len: how many bytes to copy
136 *
137 * Like i915_memcpy_from_wc(), the unaligned variant copies @len bytes from
138 * @src to @dst using * non-temporal instructions where available, but
139 * accepts that its arguments may not be aligned, but are valid for the
140 * potential 16-byte read past the end.
141 */
142void i915_unaligned_memcpy_from_wc(void *dst, const void *src, unsigned long len)
143{
144	unsigned long addr;
145
146	CI_BUG_ON(!i915_has_memcpy_from_wc());
147
148	addr = (unsigned long)src;
149	if (!IS_ALIGNED(addr, 16)) {
150		unsigned long x = min(ALIGN(addr, 16) - addr, len);
151
152		memcpy(dst, src, x);
153
154		len -= x;
155		dst += x;
156		src += x;
157	}
158
159	if (likely(len))
160		__memcpy_ntdqu(dst, src, DIV_ROUND_UP(len, 16));
161}
162
163void i915_memcpy_init_early(struct drm_i915_private *dev_priv)
164{
165	/*
166	 * Some hypervisors (e.g. KVM) don't support VEX-prefix instructions
167	 * emulation. So don't enable movntdqa in hypervisor guest.
168	 */
169	if (static_cpu_has(X86_FEATURE_XMM4_1) &&
170	    !boot_cpu_has(X86_FEATURE_HYPERVISOR))
171		static_branch_enable(&has_movntdqa);
172}