1 // SPDX-License-Identifier: GPL-2.0 OR MIT 2 3 /* 4 * Xen para-virtual DRM device 5 * 6 * Copyright (C) 2016-2018 EPAM Systems Inc. 7 * 8 * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> 9 */ 10 11 #include <linux/dma-buf.h> 12 #include <linux/scatterlist.h> 13 #include <linux/shmem_fs.h> 14 15 #include <drm/drm_gem.h> 16 #include <drm/drm_prime.h> 17 #include <drm/drm_probe_helper.h> 18 19 #include <xen/balloon.h> 20 #include <xen/xen.h> 21 22 #include "xen_drm_front.h" 23 #include "xen_drm_front_gem.h" 24 25 struct xen_gem_object { 26 struct drm_gem_object base; 27 28 size_t num_pages; 29 struct page **pages; 30 31 /* set for buffers allocated by the backend */ 32 bool be_alloc; 33 34 /* this is for imported PRIME buffer */ 35 struct sg_table *sgt_imported; 36 }; 37 38 static inline struct xen_gem_object * 39 to_xen_gem_obj(struct drm_gem_object *gem_obj) 40 { 41 return container_of(gem_obj, struct xen_gem_object, base); 42 } 43 44 static int gem_alloc_pages_array(struct xen_gem_object *xen_obj, 45 size_t buf_size) 46 { 47 xen_obj->num_pages = DIV_ROUND_UP(buf_size, PAGE_SIZE); 48 xen_obj->pages = kvmalloc_array(xen_obj->num_pages, 49 sizeof(struct page *), GFP_KERNEL); 50 return !xen_obj->pages ? -ENOMEM : 0; 51 } 52 53 static void gem_free_pages_array(struct xen_gem_object *xen_obj) 54 { 55 kvfree(xen_obj->pages); 56 xen_obj->pages = NULL; 57 } 58 59 static int xen_drm_front_gem_object_mmap(struct drm_gem_object *gem_obj, 60 struct vm_area_struct *vma) 61 { 62 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 63 int ret; 64 65 vma->vm_ops = gem_obj->funcs->vm_ops; 66 67 /* 68 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the 69 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map 70 * the whole buffer. 71 */ 72 vm_flags_mod(vma, VM_MIXEDMAP | VM_DONTEXPAND, VM_PFNMAP); 73 vma->vm_pgoff = 0; 74 75 /* 76 * According to Xen on ARM ABI (xen/include/public/arch-arm.h): 77 * all memory which is shared with other entities in the system 78 * (including the hypervisor and other guests) must reside in memory 79 * which is mapped as Normal Inner Write-Back Outer Write-Back 80 * Inner-Shareable. 81 */ 82 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 83 84 /* 85 * vm_operations_struct.fault handler will be called if CPU access 86 * to VM is here. For GPUs this isn't the case, because CPU doesn't 87 * touch the memory. Insert pages now, so both CPU and GPU are happy. 88 * 89 * FIXME: as we insert all the pages now then no .fault handler must 90 * be called, so don't provide one 91 */ 92 ret = vm_map_pages(vma, xen_obj->pages, xen_obj->num_pages); 93 if (ret < 0) 94 DRM_ERROR("Failed to map pages into vma: %d\n", ret); 95 96 return ret; 97 } 98 99 static const struct vm_operations_struct xen_drm_drv_vm_ops = { 100 .open = drm_gem_vm_open, 101 .close = drm_gem_vm_close, 102 }; 103 104 static const struct drm_gem_object_funcs xen_drm_front_gem_object_funcs = { 105 .free = xen_drm_front_gem_object_free, 106 .get_sg_table = xen_drm_front_gem_get_sg_table, 107 .vmap = xen_drm_front_gem_prime_vmap, 108 .vunmap = xen_drm_front_gem_prime_vunmap, 109 .mmap = xen_drm_front_gem_object_mmap, 110 .vm_ops = &xen_drm_drv_vm_ops, 111 }; 112 113 static struct xen_gem_object *gem_create_obj(struct drm_device *dev, 114 size_t size) 115 { 116 struct xen_gem_object *xen_obj; 117 int ret; 118 119 xen_obj = kzalloc(sizeof(*xen_obj), GFP_KERNEL); 120 if (!xen_obj) 121 return ERR_PTR(-ENOMEM); 122 123 xen_obj->base.funcs = &xen_drm_front_gem_object_funcs; 124 125 ret = drm_gem_object_init(dev, &xen_obj->base, size); 126 if (ret < 0) { 127 kfree(xen_obj); 128 return ERR_PTR(ret); 129 } 130 131 return xen_obj; 132 } 133 134 static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size) 135 { 136 struct xen_drm_front_drm_info *drm_info = dev->dev_private; 137 struct xen_gem_object *xen_obj; 138 int ret; 139 140 size = round_up(size, PAGE_SIZE); 141 xen_obj = gem_create_obj(dev, size); 142 if (IS_ERR(xen_obj)) 143 return xen_obj; 144 145 if (drm_info->front_info->cfg.be_alloc) { 146 /* 147 * backend will allocate space for this buffer, so 148 * only allocate array of pointers to pages 149 */ 150 ret = gem_alloc_pages_array(xen_obj, size); 151 if (ret < 0) 152 goto fail; 153 154 /* 155 * allocate ballooned pages which will be used to map 156 * grant references provided by the backend 157 */ 158 ret = xen_alloc_unpopulated_pages(xen_obj->num_pages, 159 xen_obj->pages); 160 if (ret < 0) { 161 DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n", 162 xen_obj->num_pages, ret); 163 gem_free_pages_array(xen_obj); 164 goto fail; 165 } 166 167 xen_obj->be_alloc = true; 168 return xen_obj; 169 } 170 /* 171 * need to allocate backing pages now, so we can share those 172 * with the backend 173 */ 174 xen_obj->num_pages = DIV_ROUND_UP(size, PAGE_SIZE); 175 xen_obj->pages = drm_gem_get_pages(&xen_obj->base); 176 if (IS_ERR(xen_obj->pages)) { 177 ret = PTR_ERR(xen_obj->pages); 178 xen_obj->pages = NULL; 179 goto fail; 180 } 181 182 return xen_obj; 183 184 fail: 185 DRM_ERROR("Failed to allocate buffer with size %zu\n", size); 186 return ERR_PTR(ret); 187 } 188 189 struct drm_gem_object *xen_drm_front_gem_create(struct drm_device *dev, 190 size_t size) 191 { 192 struct xen_gem_object *xen_obj; 193 194 xen_obj = gem_create(dev, size); 195 if (IS_ERR(xen_obj)) 196 return ERR_CAST(xen_obj); 197 198 return &xen_obj->base; 199 } 200 201 void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object *gem_obj) 202 { 203 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 204 205 if (xen_obj->base.import_attach) { 206 drm_prime_gem_destroy(&xen_obj->base, xen_obj->sgt_imported); 207 gem_free_pages_array(xen_obj); 208 } else { 209 if (xen_obj->pages) { 210 if (xen_obj->be_alloc) { 211 xen_free_unpopulated_pages(xen_obj->num_pages, 212 xen_obj->pages); 213 gem_free_pages_array(xen_obj); 214 } else { 215 drm_gem_put_pages(&xen_obj->base, 216 xen_obj->pages, true, false); 217 } 218 } 219 } 220 drm_gem_object_release(gem_obj); 221 kfree(xen_obj); 222 } 223 224 struct page **xen_drm_front_gem_get_pages(struct drm_gem_object *gem_obj) 225 { 226 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 227 228 return xen_obj->pages; 229 } 230 231 struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj) 232 { 233 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 234 235 if (!xen_obj->pages) 236 return ERR_PTR(-ENOMEM); 237 238 return drm_prime_pages_to_sg(gem_obj->dev, 239 xen_obj->pages, xen_obj->num_pages); 240 } 241 242 struct drm_gem_object * 243 xen_drm_front_gem_import_sg_table(struct drm_device *dev, 244 struct dma_buf_attachment *attach, 245 struct sg_table *sgt) 246 { 247 struct xen_drm_front_drm_info *drm_info = dev->dev_private; 248 struct xen_gem_object *xen_obj; 249 size_t size; 250 int ret; 251 252 size = attach->dmabuf->size; 253 xen_obj = gem_create_obj(dev, size); 254 if (IS_ERR(xen_obj)) 255 return ERR_CAST(xen_obj); 256 257 ret = gem_alloc_pages_array(xen_obj, size); 258 if (ret < 0) 259 return ERR_PTR(ret); 260 261 xen_obj->sgt_imported = sgt; 262 263 ret = drm_prime_sg_to_page_array(sgt, xen_obj->pages, 264 xen_obj->num_pages); 265 if (ret < 0) 266 return ERR_PTR(ret); 267 268 ret = xen_drm_front_dbuf_create(drm_info->front_info, 269 xen_drm_front_dbuf_to_cookie(&xen_obj->base), 270 0, 0, 0, size, sgt->sgl->offset, 271 xen_obj->pages); 272 if (ret < 0) 273 return ERR_PTR(ret); 274 275 DRM_DEBUG("Imported buffer of size %zu with nents %u\n", 276 size, sgt->orig_nents); 277 278 return &xen_obj->base; 279 } 280 281 int xen_drm_front_gem_prime_vmap(struct drm_gem_object *gem_obj, 282 struct iosys_map *map) 283 { 284 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 285 void *vaddr; 286 287 if (!xen_obj->pages) 288 return -ENOMEM; 289 290 /* Please see comment in gem_mmap_obj on mapping and attributes. */ 291 vaddr = vmap(xen_obj->pages, xen_obj->num_pages, 292 VM_MAP, PAGE_KERNEL); 293 if (!vaddr) 294 return -ENOMEM; 295 iosys_map_set_vaddr(map, vaddr); 296 297 return 0; 298 } 299 300 void xen_drm_front_gem_prime_vunmap(struct drm_gem_object *gem_obj, 301 struct iosys_map *map) 302 { 303 vunmap(map->vaddr); 304 } 305