diff options
Diffstat (limited to 'drivers/gpu/drm/i915/gem/i915_gem_shmem.c')
| -rw-r--r-- | drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 571 |
1 files changed, 571 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c new file mode 100644 index 000000000000..19d9ecdb2894 --- /dev/null +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -0,0 +1,571 @@ +/* + * SPDX-License-Identifier: MIT + * + * Copyright © 2014-2016 Intel Corporation + */ + +#include <linux/pagevec.h> +#include <linux/swap.h> + +#include "i915_drv.h" +#include "i915_gem_object.h" +#include "i915_scatterlist.h" + +/* + * Move pages to appropriate lru and release the pagevec, decrementing the + * ref count of those pages. + */ +static void check_release_pagevec(struct pagevec *pvec) +{ + check_move_unevictable_pages(pvec); + __pagevec_release(pvec); + cond_resched(); +} + +static int shmem_get_pages(struct drm_i915_gem_object *obj) +{ + struct drm_i915_private *i915 = to_i915(obj->base.dev); + const unsigned long page_count = obj->base.size / PAGE_SIZE; + unsigned long i; + struct address_space *mapping; + struct sg_table *st; + struct scatterlist *sg; + struct sgt_iter sgt_iter; + struct page *page; + unsigned long last_pfn = 0; /* suppress gcc warning */ + unsigned int max_segment = i915_sg_segment_size(); + unsigned int sg_page_sizes; + struct pagevec pvec; + gfp_t noreclaim; + int ret; + + /* + * Assert that the object is not currently in any GPU domain. As it + * wasn't in the GTT, there shouldn't be any way it could have been in + * a GPU cache + */ + GEM_BUG_ON(obj->read_domains & I915_GEM_GPU_DOMAINS); + GEM_BUG_ON(obj->write_domain & I915_GEM_GPU_DOMAINS); + + /* + * If there's no chance of allocating enough pages for the whole + * object, bail early. + */ + if (page_count > totalram_pages()) + return -ENOMEM; + + st = kmalloc(sizeof(*st), GFP_KERNEL); + if (!st) + return -ENOMEM; + +rebuild_st: + if (sg_alloc_table(st, page_count, GFP_KERNEL)) { + kfree(st); + return -ENOMEM; + } + + /* + * Get the list of pages out of our struct file. They'll be pinned + * at this point until we release them. + * + * Fail silently without starting the shrinker + */ + mapping = obj->base.filp->f_mapping; + mapping_set_unevictable(mapping); + noreclaim = mapping_gfp_constraint(mapping, ~__GFP_RECLAIM); + noreclaim |= __GFP_NORETRY | __GFP_NOWARN; + + sg = st->sgl; + st->nents = 0; + sg_page_sizes = 0; + for (i = 0; i < page_count; i++) { + const unsigned int shrink[] = { + I915_SHRINK_BOUND | I915_SHRINK_UNBOUND, + 0, + }, *s = shrink; + gfp_t gfp = noreclaim; + + do { + cond_resched(); + page = shmem_read_mapping_page_gfp(mapping, i, gfp); + if (!IS_ERR(page)) + break; + + if (!*s) { + ret = PTR_ERR(page); + goto err_sg; + } + + i915_gem_shrink(i915, 2 * page_count, NULL, *s++); + + /* + * We've tried hard to allocate the memory by reaping + * our own buffer, now let the real VM do its job and + * go down in flames if truly OOM. + * + * However, since graphics tend to be disposable, + * defer the oom here by reporting the ENOMEM back + * to userspace. + */ + if (!*s) { + /* reclaim and warn, but no oom */ + gfp = mapping_gfp_mask(mapping); + + /* + * Our bo are always dirty and so we require + * kswapd to reclaim our pages (direct reclaim + * does not effectively begin pageout of our + * buffers on its own). However, direct reclaim + * only waits for kswapd when under allocation + * congestion. So as a result __GFP_RECLAIM is + * unreliable and fails to actually reclaim our + * dirty pages -- unless you try over and over + * again with !__GFP_NORETRY. However, we still + * want to fail this allocation rather than + * trigger the out-of-memory killer and for + * this we want __GFP_RETRY_MAYFAIL. + */ + gfp |= __GFP_RETRY_MAYFAIL; + } + } while (1); + + if (!i || + sg->length >= max_segment || + page_to_pfn(page) != last_pfn + 1) { + if (i) { + sg_page_sizes |= sg->length; + sg = sg_next(sg); + } + st->nents++; + sg_set_page(sg, page, PAGE_SIZE, 0); + } else { + sg->length += PAGE_SIZE; + } + last_pfn = page_to_pfn(page); + + /* Check that the i965g/gm workaround works. */ + WARN_ON((gfp & __GFP_DMA32) && (last_pfn >= 0x00100000UL)); + } + if (sg) { /* loop terminated early; short sg table */ + sg_page_sizes |= sg->length; + sg_mark_end(sg); + } + + /* Trim unused sg entries to avoid wasting memory. */ + i915_sg_trim(st); + + ret = i915_gem_gtt_prepare_pages(obj, st); + if (ret) { + /* + * DMA remapping failed? One possible cause is that + * it could not reserve enough large entries, asking + * for PAGE_SIZE chunks instead may be helpful. + */ + if (max_segment > PAGE_SIZE) { + for_each_sgt_page(page, sgt_iter, st) + put_page(page); + sg_free_table(st); + + max_segment = PAGE_SIZE; + goto rebuild_st; + } else { + dev_warn(&i915->drm.pdev->dev, + "Failed to DMA remap %lu pages\n", + page_count); + goto err_pages; + } + } + + if (i915_gem_object_needs_bit17_swizzle(obj)) + i915_gem_object_do_bit_17_swizzle(obj, st); + + __i915_gem_object_set_pages(obj, st, sg_page_sizes); + + return 0; + +err_sg: + sg_mark_end(sg); +err_pages: + mapping_clear_unevictable(mapping); + pagevec_init(&pvec); + for_each_sgt_page(page, sgt_iter, st) { + if (!pagevec_add(&pvec, page)) + check_release_pagevec(&pvec); + } + if (pagevec_count(&pvec)) + check_release_pagevec(&pvec); + sg_free_table(st); + kfree(st); + + /* + * shmemfs first checks if there is enough memory to allocate the page + * and reports ENOSPC should there be insufficient, along with the usual + * ENOMEM for a genuine allocation failure. + * + * We use ENOSPC in our driver to mean that we have run out of aperture + * space and so want to translate the error from shmemfs back to our + * usual understanding of ENOMEM. + */ + if (ret == -ENOSPC) + ret = -ENOMEM; + + return ret; +} + +static void +shmem_truncate(struct drm_i915_gem_object *obj) +{ + /* + * Our goal here is to return as much of the memory as + * is possible back to the system as we are called from OOM. + * To do this we must instruct the shmfs to drop all of its + * backing pages, *now*. + */ + shmem_truncate_range(file_inode(obj->base.filp), 0, (loff_t)-1); + obj->mm.madv = __I915_MADV_PURGED; + obj->mm.pages = ERR_PTR(-EFAULT); +} + +static void +shmem_writeback(struct drm_i915_gem_object *obj) +{ + struct address_space *mapping; + struct writeback_control wbc = { + .sync_mode = WB_SYNC_NONE, + .nr_to_write = SWAP_CLUSTER_MAX, + .range_start = 0, + .range_end = LLONG_MAX, + .for_reclaim = 1, + }; + unsigned long i; + + /* + * Leave mmapings intact (GTT will have been revoked on unbinding, + * leaving only CPU mmapings around) and add those pages to the LRU + * instead of invoking writeback so they are aged and paged out + * as normal. + */ + mapping = obj->base.filp->f_mapping; + + /* Begin writeback on each dirty page */ + for (i = 0; i < obj->base.size >> PAGE_SHIFT; i++) { + struct page *page; + + page = find_lock_entry(mapping, i); + if (!page || xa_is_value(page)) + continue; + + if (!page_mapped(page) && clear_page_dirty_for_io(page)) { + int ret; + + SetPageReclaim(page); + ret = mapping->a_ops->writepage(page, &wbc); + if (!PageWriteback(page)) + ClearPageReclaim(page); + if (!ret) + goto put; + } + unlock_page(page); +put: + put_page(page); + } +} + +void +__i915_gem_object_release_shmem(struct drm_i915_gem_object *obj, + struct sg_table *pages, + bool needs_clflush) +{ + GEM_BUG_ON(obj->mm.madv == __I915_MADV_PURGED); + + if (obj->mm.madv == I915_MADV_DONTNEED) + obj->mm.dirty = false; + + if (needs_clflush && + (obj->read_domains & I915_GEM_DOMAIN_CPU) == 0 && + !(obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ)) + drm_clflush_sg(pages); + + __start_cpu_write(obj); +} + +static void +shmem_put_pages(struct drm_i915_gem_object *obj, struct sg_table *pages) +{ + struct sgt_iter sgt_iter; + struct pagevec pvec; + struct page *page; + + __i915_gem_object_release_shmem(obj, pages, true); + + i915_gem_gtt_finish_pages(obj, pages); + + if (i915_gem_object_needs_bit17_swizzle(obj)) + i915_gem_object_save_bit_17_swizzle(obj, pages); + + mapping_clear_unevictable(file_inode(obj->base.filp)->i_mapping); + + pagevec_init(&pvec); + for_each_sgt_page(page, sgt_iter, pages) { + if (obj->mm.dirty) + set_page_dirty(page); + + if (obj->mm.madv == I915_MADV_WILLNEED) + mark_page_accessed(page); + + if (!pagevec_add(&pvec, page)) + check_release_pagevec(&pvec); + } + if (pagevec_count(&pvec)) + check_release_pagevec(&pvec); + obj->mm.dirty = false; + + sg_free_table(pages); + kfree(pages); +} + +static int +shmem_pwrite(struct drm_i915_gem_object *obj, + const struct drm_i915_gem_pwrite *arg) +{ + struct address_space *mapping = obj->base.filp->f_mapping; + char __user *user_data = u64_to_user_ptr(arg->data_ptr); + u64 remain, offset; + unsigned int pg; + + /* Caller already validated user args */ + GEM_BUG_ON(!access_ok(user_data, arg->size)); + + /* + * Before we instantiate/pin the backing store for our use, we + * can prepopulate the shmemfs filp efficiently using a write into + * the pagecache. We avoid the penalty of instantiating all the + * pages, important if the user is just writing to a few and never + * uses the object on the GPU, and using a direct write into shmemfs + * allows it to avoid the cost of retrieving a page (either swapin + * or clearing-before-use) before it is overwritten. + */ + if (i915_gem_object_has_pages(obj)) + return -ENODEV; + + if (obj->mm.madv != I915_MADV_WILLNEED) + return -EFAULT; + + /* + * Before the pages are instantiated the object is treated as being + * in the CPU domain. The pages will be clflushed as required before + * use, and we can freely write into the pages directly. If userspace + * races pwrite with any other operation; corruption will ensue - + * that is userspace's prerogative! + */ + + remain = arg->size; + offset = arg->offset; + pg = offset_in_page(offset); + + do { + unsigned int len, unwritten; + struct page *page; + void *data, *vaddr; + int err; + char c; + + len = PAGE_SIZE - pg; + if (len > remain) + len = remain; + + /* Prefault the user page to reduce potential recursion */ + err = __get_user(c, user_data); + if (err) + return err; + + err = __get_user(c, user_data + len - 1); + if (err) + return err; + + err = pagecache_write_begin(obj->base.filp, mapping, + offset, len, 0, + &page, &data); + if (err < 0) + return err; + + vaddr = kmap_atomic(page); + unwritten = __copy_from_user_inatomic(vaddr + pg, + user_data, + len); + kunmap_atomic(vaddr); + + err = pagecache_write_end(obj->base.filp, mapping, + offset, len, len - unwritten, + page, data); + if (err < 0) + return err; + + /* We don't handle -EFAULT, leave it to the caller to check */ + if (unwritten) + return -ENODEV; + + remain -= len; + user_data += len; + offset += len; + pg = 0; + } while (remain); + + return 0; +} + +const struct drm_i915_gem_object_ops i915_gem_shmem_ops = { + .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE | + I915_GEM_OBJECT_IS_SHRINKABLE, + + .get_pages = shmem_get_pages, + .put_pages = shmem_put_pages, + .truncate = shmem_truncate, + .writeback = shmem_writeback, + + .pwrite = shmem_pwrite, +}; + +static int create_shmem(struct drm_i915_private *i915, + struct drm_gem_object *obj, + size_t size) +{ + unsigned long flags = VM_NORESERVE; + struct file *filp; + + drm_gem_private_object_init(&i915->drm, obj, size); + + if (i915->mm.gemfs) + filp = shmem_file_setup_with_mnt(i915->mm.gemfs, "i915", size, + flags); + else + filp = shmem_file_setup("i915", size, flags); + if (IS_ERR(filp)) + return PTR_ERR(filp); + + obj->filp = filp; + return 0; +} + +struct drm_i915_gem_object * +i915_gem_object_create_shmem(struct drm_i915_private *i915, u64 size) +{ + struct drm_i915_gem_object *obj; + struct address_space *mapping; + unsigned int cache_level; + gfp_t mask; + int ret; + + /* There is a prevalence of the assumption that we fit the object's + * page count inside a 32bit _signed_ variable. Let's document this and + * catch if we ever need to fix it. In the meantime, if you do spot + * such a local variable, please consider fixing! + */ + if (size >> PAGE_SHIFT > INT_MAX) + return ERR_PTR(-E2BIG); + + if (overflows_type(size, obj->base.size)) + return ERR_PTR(-E2BIG); + + obj = i915_gem_object_alloc(); + if (!obj) + return ERR_PTR(-ENOMEM); + + ret = create_shmem(i915, &obj->base, size); + if (ret) + goto fail; + + mask = GFP_HIGHUSER | __GFP_RECLAIMABLE; + if (IS_I965GM(i915) || IS_I965G(i915)) { + /* 965gm cannot relocate objects above 4GiB. */ + mask &= ~__GFP_HIGHMEM; + mask |= __GFP_DMA32; + } + + mapping = obj->base.filp->f_mapping; + mapping_set_gfp_mask(mapping, mask); + GEM_BUG_ON(!(mapping_gfp_mask(mapping) & __GFP_RECLAIM)); + + i915_gem_object_init(obj, &i915_gem_shmem_ops); + + obj->write_domain = I915_GEM_DOMAIN_CPU; + obj->read_domains = I915_GEM_DOMAIN_CPU; + + if (HAS_LLC(i915)) + /* On some devices, we can have the GPU use the LLC (the CPU + * cache) for about a 10% performance improvement + * compared to uncached. Graphics requests other than + * display scanout are coherent with the CPU in + * accessing this cache. This means in this mode we + * don't need to clflush on the CPU side, and on the + * GPU side we only need to flush internal caches to + * get data visible to the CPU. + * + * However, we maintain the display planes as UC, and so + * need to rebind when first used as such. + */ + cache_level = I915_CACHE_LLC; + else + cache_level = I915_CACHE_NONE; + + i915_gem_object_set_cache_coherency(obj, cache_level); + + trace_i915_gem_object_create(obj); + + return obj; + +fail: + i915_gem_object_free(obj); + return ERR_PTR(ret); +} + +/* Allocate a new GEM object and fill it with the supplied data */ +struct drm_i915_gem_object * +i915_gem_object_create_shmem_from_data(struct drm_i915_private *dev_priv, + const void *data, size_t size) +{ + struct drm_i915_gem_object *obj; + struct file *file; + size_t offset; + int err; + + obj = i915_gem_object_create_shmem(dev_priv, round_up(size, PAGE_SIZE)); + if (IS_ERR(obj)) + return obj; + + GEM_BUG_ON(obj->write_domain != I915_GEM_DOMAIN_CPU); + + file = obj->base.filp; + offset = 0; + do { + unsigned int len = min_t(typeof(size), size, PAGE_SIZE); + struct page *page; + void *pgdata, *vaddr; + + err = pagecache_write_begin(file, file->f_mapping, + offset, len, 0, + &page, &pgdata); + if (err < 0) + goto fail; + + vaddr = kmap(page); + memcpy(vaddr, data, len); + kunmap(page); + + err = pagecache_write_end(file, file->f_mapping, + offset, len, len, + page, pgdata); + if (err < 0) + goto fail; + + size -= len; + data += len; + offset += len; + } while (size); + + return obj; + +fail: + i915_gem_object_put(obj); + return ERR_PTR(err); +} |