On Thu, Aug 01, 2019 at 01:44:58PM +0100, Chris Wilson wrote:
> commit 7e9e5ead55be ("drm/vgem: fix cache synchronization on arm/arm64")
> broke all of the !llc i915-vgem coherency tests in CI, and left the HW
> very, very unhappy (which is even more scary).
>
> Fixes: 7e9e5ead55be ("drm/vgem: fix cache synchronization on arm/arm64")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Acked-by: Sean Paul <sean@xxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: Rob Clark <robdclark@xxxxxxxxxxxx>
> Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/vgem/vgem_drv.c | 130 ++++++++++++--------------------
> 1 file changed, 47 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index b98689fb0d5d..5bd60ded3d81 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -54,16 +54,10 @@ static struct vgem_device {
> struct platform_device *platform;
> } *vgem_device;
>
> -static void sync_and_unpin(struct drm_vgem_gem_object *bo);
> -static struct page **pin_and_sync(struct drm_vgem_gem_object *bo);
> -
> static void vgem_gem_free_object(struct drm_gem_object *obj)
> {
> struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
>
> - if (!obj->import_attach)
> - sync_and_unpin(vgem_obj);
> -
> kvfree(vgem_obj->pages);
> mutex_destroy(&vgem_obj->pages_lock);
>
> @@ -91,15 +85,40 @@ static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
> return VM_FAULT_SIGBUS;
>
> mutex_lock(&obj->pages_lock);
> - if (!obj->pages)
> - pin_and_sync(obj);
> if (obj->pages) {
> get_page(obj->pages[page_offset]);
> vmf->page = obj->pages[page_offset];
> ret = 0;
> }
> mutex_unlock(&obj->pages_lock);
> + if (ret) {
> + struct page *page;
> +
> + page = shmem_read_mapping_page(
> + file_inode(obj->base.filp)->i_mapping,
> + page_offset);
> + if (!IS_ERR(page)) {
> + vmf->page = page;
> + ret = 0;
> + } else switch (PTR_ERR(page)) {
> + case -ENOSPC:
> + case -ENOMEM:
> + ret = VM_FAULT_OOM;
> + break;
> + case -EBUSY:
> + ret = VM_FAULT_RETRY;
> + break;
> + case -EFAULT:
> + case -EINVAL:
> + ret = VM_FAULT_SIGBUS;
> + break;
> + default:
> + WARN_ON(PTR_ERR(page));
> + ret = VM_FAULT_SIGBUS;
> + break;
> + }
>
> + }
> return ret;
> }
>
> @@ -265,93 +284,32 @@ static const struct file_operations vgem_driver_fops = {
> .release = drm_release,
> };
>
> -/* Called under pages_lock, except in free path (where it can't race): */
> -static void sync_and_unpin(struct drm_vgem_gem_object *bo)
> -{
> - struct drm_device *dev = bo->base.dev;
> -
> - if (bo->table) {
> - dma_sync_sg_for_cpu(dev->dev, bo->table->sgl,
> - bo->table->nents, DMA_BIDIRECTIONAL);
> - sg_free_table(bo->table);
> - kfree(bo->table);
> - bo->table = NULL;
> - }
> -
> - if (bo->pages) {
> - drm_gem_put_pages(&bo->base, bo->pages, true, true);
> - bo->pages = NULL;
> - }
> -}
> -
> -static struct page **pin_and_sync(struct drm_vgem_gem_object *bo)
> -{
> - struct drm_device *dev = bo->base.dev;
> - int npages = bo->base.size >> PAGE_SHIFT;
> - struct page **pages;
> - struct sg_table *sgt;
> -
> - WARN_ON(!mutex_is_locked(&bo->pages_lock));
> -
> - pages = drm_gem_get_pages(&bo->base);
> - if (IS_ERR(pages)) {
> - bo->pages_pin_count--;
> - mutex_unlock(&bo->pages_lock);
> - return pages;
> - }
> -
> - sgt = drm_prime_pages_to_sg(pages, npages);
> - if (IS_ERR(sgt)) {
> - dev_err(dev->dev,
> - "failed to allocate sgt: %ld\n",
> - PTR_ERR(bo->table));
> - drm_gem_put_pages(&bo->base, pages, false, false);
> - mutex_unlock(&bo->pages_lock);
> - return ERR_CAST(bo->table);
> - }
> -
> - /*
> - * Flush the object from the CPU cache so that importers
> - * can rely on coherent indirect access via the exported
> - * dma-address.
> - */
> - dma_sync_sg_for_device(dev->dev, sgt->sgl,
> - sgt->nents, DMA_BIDIRECTIONAL);
> -
> - bo->pages = pages;
> - bo->table = sgt;
> -
> - return pages;
> -}
> -
> static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> {
> - struct page **pages;
> -
> mutex_lock(&bo->pages_lock);
> - if (bo->pages_pin_count++ == 0 && !bo->pages) {
> - pages = pin_and_sync(bo);
> - } else {
> - WARN_ON(!bo->pages);
> - pages = bo->pages;
> + 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 pages;
> + return bo->pages;
> }
>
> static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> {
> - /*
> - * We shouldn't hit this for imported bo's.. in the import
> - * case we don't own the scatter-table
> - */
> - WARN_ON(bo->base.import_attach);
> -
> mutex_lock(&bo->pages_lock);
> if (--bo->pages_pin_count == 0) {
> - WARN_ON(!bo->table);
> - sync_and_unpin(bo);
> + drm_gem_put_pages(&bo->base, bo->pages, true, true);
> + bo->pages = NULL;
> }
> mutex_unlock(&bo->pages_lock);
> }
> @@ -359,12 +317,18 @@ static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> 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;
>
> 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);
> +
> return 0;
> }
>
> --
> 2.23.0.rc0
>
> _______________________________________________
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Sean Paul, Software Engineer, Google / Chromium OS
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