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_fb_helper.h> 16 #include <drm/drm_gem.h> 17 #include <drm/drm_prime.h> 18 #include <drm/drm_probe_helper.h> 19 20 #include <xen/balloon.h> 21 #include <xen/xen.h> 22 23 #include "xen_drm_front.h" 24 #include "xen_drm_front_gem.h" 25 26 struct xen_gem_object { 27 struct drm_gem_object base; 28 29 size_t num_pages; 30 struct page **pages; 31 32 /* set for buffers allocated by the backend */ 33 bool be_alloc; 34 35 /* this is for imported PRIME buffer */ 36 struct sg_table *sgt_imported; 37 }; 38 39 static inline struct xen_gem_object * 40 to_xen_gem_obj(struct drm_gem_object *gem_obj) 41 { 42 return container_of(gem_obj, struct xen_gem_object, base); 43 } 44 45 static int gem_alloc_pages_array(struct xen_gem_object *xen_obj, 46 size_t buf_size) 47 { 48 xen_obj->num_pages = DIV_ROUND_UP(buf_size, PAGE_SIZE); 49 xen_obj->pages = kvmalloc_array(xen_obj->num_pages, 50 sizeof(struct page *), GFP_KERNEL); 51 return !xen_obj->pages ? -ENOMEM : 0; 52 } 53 54 static void gem_free_pages_array(struct xen_gem_object *xen_obj) 55 { 56 kvfree(xen_obj->pages); 57 xen_obj->pages = NULL; 58 } 59 60 static struct xen_gem_object *gem_create_obj(struct drm_device *dev, 61 size_t size) 62 { 63 struct xen_gem_object *xen_obj; 64 int ret; 65 66 xen_obj = kzalloc(sizeof(*xen_obj), GFP_KERNEL); 67 if (!xen_obj) 68 return ERR_PTR(-ENOMEM); 69 70 ret = drm_gem_object_init(dev, &xen_obj->base, size); 71 if (ret < 0) { 72 kfree(xen_obj); 73 return ERR_PTR(ret); 74 } 75 76 return xen_obj; 77 } 78 79 static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size) 80 { 81 struct xen_drm_front_drm_info *drm_info = dev->dev_private; 82 struct xen_gem_object *xen_obj; 83 int ret; 84 85 size = round_up(size, PAGE_SIZE); 86 xen_obj = gem_create_obj(dev, size); 87 if (IS_ERR(xen_obj)) 88 return xen_obj; 89 90 if (drm_info->front_info->cfg.be_alloc) { 91 /* 92 * backend will allocate space for this buffer, so 93 * only allocate array of pointers to pages 94 */ 95 ret = gem_alloc_pages_array(xen_obj, size); 96 if (ret < 0) 97 goto fail; 98 99 /* 100 * allocate ballooned pages which will be used to map 101 * grant references provided by the backend 102 */ 103 ret = xen_alloc_unpopulated_pages(xen_obj->num_pages, 104 xen_obj->pages); 105 if (ret < 0) { 106 DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n", 107 xen_obj->num_pages, ret); 108 gem_free_pages_array(xen_obj); 109 goto fail; 110 } 111 112 xen_obj->be_alloc = true; 113 return xen_obj; 114 } 115 /* 116 * need to allocate backing pages now, so we can share those 117 * with the backend 118 */ 119 xen_obj->num_pages = DIV_ROUND_UP(size, PAGE_SIZE); 120 xen_obj->pages = drm_gem_get_pages(&xen_obj->base); 121 if (IS_ERR(xen_obj->pages)) { 122 ret = PTR_ERR(xen_obj->pages); 123 xen_obj->pages = NULL; 124 goto fail; 125 } 126 127 return xen_obj; 128 129 fail: 130 DRM_ERROR("Failed to allocate buffer with size %zu\n", size); 131 return ERR_PTR(ret); 132 } 133 134 struct drm_gem_object *xen_drm_front_gem_create(struct drm_device *dev, 135 size_t size) 136 { 137 struct xen_gem_object *xen_obj; 138 139 xen_obj = gem_create(dev, size); 140 if (IS_ERR(xen_obj)) 141 return ERR_CAST(xen_obj); 142 143 return &xen_obj->base; 144 } 145 146 void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object *gem_obj) 147 { 148 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 149 150 if (xen_obj->base.import_attach) { 151 drm_prime_gem_destroy(&xen_obj->base, xen_obj->sgt_imported); 152 gem_free_pages_array(xen_obj); 153 } else { 154 if (xen_obj->pages) { 155 if (xen_obj->be_alloc) { 156 xen_free_unpopulated_pages(xen_obj->num_pages, 157 xen_obj->pages); 158 gem_free_pages_array(xen_obj); 159 } else { 160 drm_gem_put_pages(&xen_obj->base, 161 xen_obj->pages, true, false); 162 } 163 } 164 } 165 drm_gem_object_release(gem_obj); 166 kfree(xen_obj); 167 } 168 169 struct page **xen_drm_front_gem_get_pages(struct drm_gem_object *gem_obj) 170 { 171 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 172 173 return xen_obj->pages; 174 } 175 176 struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj) 177 { 178 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 179 180 if (!xen_obj->pages) 181 return ERR_PTR(-ENOMEM); 182 183 return drm_prime_pages_to_sg(xen_obj->pages, xen_obj->num_pages); 184 } 185 186 struct drm_gem_object * 187 xen_drm_front_gem_import_sg_table(struct drm_device *dev, 188 struct dma_buf_attachment *attach, 189 struct sg_table *sgt) 190 { 191 struct xen_drm_front_drm_info *drm_info = dev->dev_private; 192 struct xen_gem_object *xen_obj; 193 size_t size; 194 int ret; 195 196 size = attach->dmabuf->size; 197 xen_obj = gem_create_obj(dev, size); 198 if (IS_ERR(xen_obj)) 199 return ERR_CAST(xen_obj); 200 201 ret = gem_alloc_pages_array(xen_obj, size); 202 if (ret < 0) 203 return ERR_PTR(ret); 204 205 xen_obj->sgt_imported = sgt; 206 207 ret = drm_prime_sg_to_page_addr_arrays(sgt, xen_obj->pages, 208 NULL, xen_obj->num_pages); 209 if (ret < 0) 210 return ERR_PTR(ret); 211 212 ret = xen_drm_front_dbuf_create(drm_info->front_info, 213 xen_drm_front_dbuf_to_cookie(&xen_obj->base), 214 0, 0, 0, size, sgt->sgl->offset, 215 xen_obj->pages); 216 if (ret < 0) 217 return ERR_PTR(ret); 218 219 DRM_DEBUG("Imported buffer of size %zu with nents %u\n", 220 size, sgt->nents); 221 222 return &xen_obj->base; 223 } 224 225 static int gem_mmap_obj(struct xen_gem_object *xen_obj, 226 struct vm_area_struct *vma) 227 { 228 int ret; 229 230 /* 231 * clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the 232 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map 233 * the whole buffer. 234 */ 235 vma->vm_flags &= ~VM_PFNMAP; 236 vma->vm_flags |= VM_MIXEDMAP; 237 vma->vm_pgoff = 0; 238 /* 239 * According to Xen on ARM ABI (xen/include/public/arch-arm.h): 240 * all memory which is shared with other entities in the system 241 * (including the hypervisor and other guests) must reside in memory 242 * which is mapped as Normal Inner Write-Back Outer Write-Back 243 * Inner-Shareable. 244 */ 245 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 246 247 /* 248 * vm_operations_struct.fault handler will be called if CPU access 249 * to VM is here. For GPUs this isn't the case, because CPU 250 * doesn't touch the memory. Insert pages now, so both CPU and GPU are 251 * happy. 252 * FIXME: as we insert all the pages now then no .fault handler must 253 * be called, so don't provide one 254 */ 255 ret = vm_map_pages(vma, xen_obj->pages, xen_obj->num_pages); 256 if (ret < 0) 257 DRM_ERROR("Failed to map pages into vma: %d\n", ret); 258 259 return ret; 260 } 261 262 int xen_drm_front_gem_mmap(struct file *filp, struct vm_area_struct *vma) 263 { 264 struct xen_gem_object *xen_obj; 265 struct drm_gem_object *gem_obj; 266 int ret; 267 268 ret = drm_gem_mmap(filp, vma); 269 if (ret < 0) 270 return ret; 271 272 gem_obj = vma->vm_private_data; 273 xen_obj = to_xen_gem_obj(gem_obj); 274 return gem_mmap_obj(xen_obj, vma); 275 } 276 277 void *xen_drm_front_gem_prime_vmap(struct drm_gem_object *gem_obj) 278 { 279 struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj); 280 281 if (!xen_obj->pages) 282 return NULL; 283 284 /* Please see comment in gem_mmap_obj on mapping and attributes. */ 285 return vmap(xen_obj->pages, xen_obj->num_pages, 286 VM_MAP, PAGE_KERNEL); 287 } 288 289 void xen_drm_front_gem_prime_vunmap(struct drm_gem_object *gem_obj, 290 void *vaddr) 291 { 292 vunmap(vaddr); 293 } 294 295 int xen_drm_front_gem_prime_mmap(struct drm_gem_object *gem_obj, 296 struct vm_area_struct *vma) 297 { 298 struct xen_gem_object *xen_obj; 299 int ret; 300 301 ret = drm_gem_mmap_obj(gem_obj, gem_obj->size, vma); 302 if (ret < 0) 303 return ret; 304 305 xen_obj = to_xen_gem_obj(gem_obj); 306 return gem_mmap_obj(xen_obj, vma); 307 } 308