From 71bb23c707c141b176bc084179ca5ee58d5fd26a Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 22 Jun 2017 14:46:17 +0100 Subject: drm/vgem: Pin our pages for dmabuf exports When the caller maps their dmabuf and we return an sg_table, the caller doesn't expect the pages beneath that sg_table to vanish on a whim (i.e. under mempressure). The contract is that the pages are pinned for the duration of the mapping (from dma_buf_map_attachment() to dma_buf_unmap_attachment). To comply, we need to introduce our own vgem_object.pages_pin_count and elevate it across the mapping. However, the drm_prime interface we use calls drv->prime_pin on dma_buf_attach and drv->prime_unpin on dma_buf_detach, which while that does cover the mapping is much broader than is desired -- but it will do for now. v2: also hold the pin across prime_vmap/vunmap Reported-by: Tomi Sarvela Testcase: igt/gem_concurrent_blit/*swap*vgem* Fixes: 5ba6c9ff961a ("drm/vgem: Fix mmaping") Signed-off-by: Chris Wilson Cc: Tomi Sarvela Cc: Laura Abbott Cc: Sean Paul Cc: Matthew Auld Cc: Daniel Vetter Cc: # needs a backport Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20170622134617.17912-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/vgem/vgem_drv.c | 81 ++++++++++++++++++++++++++++++----------- drivers/gpu/drm/vgem/vgem_drv.h | 4 ++ 2 files changed, 64 insertions(+), 21 deletions(-) (limited to 'drivers/gpu/drm/vgem') diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index 18f401b442c2..c938af8c40cf 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -52,6 +52,7 @@ static void vgem_gem_free_object(struct drm_gem_object *obj) struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj); kvfree(vgem_obj->pages); + mutex_destroy(&vgem_obj->pages_lock); if (obj->import_attach) drm_prime_gem_destroy(obj, vgem_obj->table); @@ -76,11 +77,15 @@ static int vgem_gem_fault(struct vm_fault *vmf) if (page_offset > num_pages) return VM_FAULT_SIGBUS; + ret = -ENOENT; + mutex_lock(&obj->pages_lock); if (obj->pages) { get_page(obj->pages[page_offset]); vmf->page = obj->pages[page_offset]; ret = 0; - } else { + } + mutex_unlock(&obj->pages_lock); + if (ret) { struct page *page; page = shmem_read_mapping_page( @@ -161,6 +166,8 @@ static struct drm_vgem_gem_object *__vgem_gem_create(struct drm_device *dev, return ERR_PTR(ret); } + mutex_init(&obj->pages_lock); + return obj; } @@ -274,37 +281,66 @@ static const struct file_operations vgem_driver_fops = { .release = drm_release, }; +static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo) +{ + mutex_lock(&bo->pages_lock); + if (bo->pages_pin_count++ == 0) { + struct page **pages; + + pages = drm_gem_get_pages(&bo->base); + if (IS_ERR(pages)) { + bo->pages_pin_count--; + mutex_unlock(&bo->pages_lock); + return pages; + } + + bo->pages = pages; + } + mutex_unlock(&bo->pages_lock); + + return bo->pages; +} + +static void vgem_unpin_pages(struct drm_vgem_gem_object *bo) +{ + mutex_lock(&bo->pages_lock); + if (--bo->pages_pin_count == 0) { + drm_gem_put_pages(&bo->base, bo->pages, true, true); + bo->pages = NULL; + } + mutex_unlock(&bo->pages_lock); +} + static int vgem_prime_pin(struct drm_gem_object *obj) { + struct drm_vgem_gem_object *bo = to_vgem_bo(obj); long n_pages = obj->size >> PAGE_SHIFT; struct page **pages; - /* Flush the object from the CPU cache so that importers can rely - * on coherent indirect access via the exported dma-address. - */ - pages = drm_gem_get_pages(obj); + pages = vgem_pin_pages(bo); if (IS_ERR(pages)) return PTR_ERR(pages); + /* Flush the object from the CPU cache so that importers can rely + * on coherent indirect access via the exported dma-address. + */ drm_clflush_pages(pages, n_pages); - drm_gem_put_pages(obj, pages, true, false); return 0; } -static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object *obj) +static void vgem_prime_unpin(struct drm_gem_object *obj) { - struct sg_table *st; - struct page **pages; + struct drm_vgem_gem_object *bo = to_vgem_bo(obj); - pages = drm_gem_get_pages(obj); - if (IS_ERR(pages)) - return ERR_CAST(pages); + vgem_unpin_pages(bo); +} - st = drm_prime_pages_to_sg(pages, obj->size >> PAGE_SHIFT); - drm_gem_put_pages(obj, pages, false, false); +static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object *obj) +{ + struct drm_vgem_gem_object *bo = to_vgem_bo(obj); - return st; + return drm_prime_pages_to_sg(bo->pages, bo->base.size >> PAGE_SHIFT); } static struct drm_gem_object* vgem_prime_import(struct drm_device *dev, @@ -333,6 +369,8 @@ static struct drm_gem_object *vgem_prime_import_sg_table(struct drm_device *dev, __vgem_gem_destroy(obj); return ERR_PTR(-ENOMEM); } + + obj->pages_pin_count++; /* perma-pinned */ drm_prime_sg_to_page_addr_arrays(obj->table, obj->pages, NULL, npages); return &obj->base; @@ -340,23 +378,23 @@ static struct drm_gem_object *vgem_prime_import_sg_table(struct drm_device *dev, static void *vgem_prime_vmap(struct drm_gem_object *obj) { + struct drm_vgem_gem_object *bo = to_vgem_bo(obj); long n_pages = obj->size >> PAGE_SHIFT; struct page **pages; - void *addr; - pages = drm_gem_get_pages(obj); + pages = vgem_pin_pages(bo); if (IS_ERR(pages)) return NULL; - addr = vmap(pages, n_pages, 0, pgprot_writecombine(PAGE_KERNEL)); - drm_gem_put_pages(obj, pages, false, false); - - return addr; + return vmap(pages, n_pages, 0, pgprot_writecombine(PAGE_KERNEL)); } static void vgem_prime_vunmap(struct drm_gem_object *obj, void *vaddr) { + struct drm_vgem_gem_object *bo = to_vgem_bo(obj); + vunmap(vaddr); + vgem_unpin_pages(bo); } static int vgem_prime_mmap(struct drm_gem_object *obj, @@ -409,6 +447,7 @@ static struct drm_driver vgem_driver = { .prime_handle_to_fd = drm_gem_prime_handle_to_fd, .prime_fd_to_handle = drm_gem_prime_fd_to_handle, .gem_prime_pin = vgem_prime_pin, + .gem_prime_unpin = vgem_prime_unpin, .gem_prime_import = vgem_prime_import, .gem_prime_export = drm_gem_prime_export, .gem_prime_import_sg_table = vgem_prime_import_sg_table, diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h index 1aae01419112..5c8f6d619ff3 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.h +++ b/drivers/gpu/drm/vgem/vgem_drv.h @@ -43,7 +43,11 @@ struct vgem_file { #define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base) struct drm_vgem_gem_object { struct drm_gem_object base; + struct page **pages; + unsigned int pages_pin_count; + struct mutex pages_lock; + struct sg_table *table; }; -- cgit