On Mon, Oct 21, 2019 at 4:50 PM Daniel Vetter <daniel.vetter@xxxxxxxx> wrote:
>
> We can't copy_*_user while holding reservations, that will (soon even
> for nouveau) lead to deadlocks. And it breaks the cross-driver
> contract around dma_resv.
>
> Fix this by adding a slowpath for when we need relocations, and by
> pushing the writeback of the new presumed offsets to the very end.
>
> Aside from "it compiles" entirely untested unfortunately.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> Cc: Ilia Mirkin <imirkin@xxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
> Cc: nouveau@xxxxxxxxxxxxxxxxxxxxx
Ping for review/testing/ack, I'd really like to get this in.
-Daniel
> ---
> drivers/gpu/drm/nouveau/nouveau_gem.c | 57 ++++++++++++++++++---------
> 1 file changed, 38 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
> index 1324c19f4e5c..05ec8edd6a8b 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_gem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
> @@ -484,12 +484,9 @@ validate_init(struct nouveau_channel *chan, struct drm_file *file_priv,
>
> static int
> validate_list(struct nouveau_channel *chan, struct nouveau_cli *cli,
> - struct list_head *list, struct drm_nouveau_gem_pushbuf_bo *pbbo,
> - uint64_t user_pbbo_ptr)
> + struct list_head *list, struct drm_nouveau_gem_pushbuf_bo *pbbo)
> {
> struct nouveau_drm *drm = chan->drm;
> - struct drm_nouveau_gem_pushbuf_bo __user *upbbo =
> - (void __force __user *)(uintptr_t)user_pbbo_ptr;
> struct nouveau_bo *nvbo;
> int ret, relocs = 0;
>
> @@ -533,10 +530,6 @@ validate_list(struct nouveau_channel *chan, struct nouveau_cli *cli,
> b->presumed.offset = nvbo->bo.offset;
> b->presumed.valid = 0;
> relocs++;
> -
> - if (copy_to_user(&upbbo[nvbo->pbbo_index].presumed,
> - &b->presumed, sizeof(b->presumed)))
> - return -EFAULT;
> }
> }
>
> @@ -547,8 +540,8 @@ static int
> nouveau_gem_pushbuf_validate(struct nouveau_channel *chan,
> struct drm_file *file_priv,
> struct drm_nouveau_gem_pushbuf_bo *pbbo,
> - uint64_t user_buffers, int nr_buffers,
> - struct validate_op *op, int *apply_relocs)
> + int nr_buffers,
> + struct validate_op *op, bool *apply_relocs)
> {
> struct nouveau_cli *cli = nouveau_cli(file_priv);
> int ret;
> @@ -565,7 +558,7 @@ nouveau_gem_pushbuf_validate(struct nouveau_channel *chan,
> return ret;
> }
>
> - ret = validate_list(chan, cli, &op->list, pbbo, user_buffers);
> + ret = validate_list(chan, cli, &op->list, pbbo);
> if (unlikely(ret < 0)) {
> if (ret != -ERESTARTSYS)
> NV_PRINTK(err, cli, "validating bo list\n");
> @@ -605,16 +598,12 @@ u_memcpya(uint64_t user, unsigned nmemb, unsigned size)
> static int
> nouveau_gem_pushbuf_reloc_apply(struct nouveau_cli *cli,
> struct drm_nouveau_gem_pushbuf *req,
> + struct drm_nouveau_gem_pushbuf_reloc *reloc,
> struct drm_nouveau_gem_pushbuf_bo *bo)
> {
> - struct drm_nouveau_gem_pushbuf_reloc *reloc = NULL;
> int ret = 0;
> unsigned i;
>
> - reloc = u_memcpya(req->relocs, req->nr_relocs, sizeof(*reloc));
> - if (IS_ERR(reloc))
> - return PTR_ERR(reloc);
> -
> for (i = 0; i < req->nr_relocs; i++) {
> struct drm_nouveau_gem_pushbuf_reloc *r = &reloc[i];
> struct drm_nouveau_gem_pushbuf_bo *b;
> @@ -693,11 +682,13 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data,
> struct nouveau_drm *drm = nouveau_drm(dev);
> struct drm_nouveau_gem_pushbuf *req = data;
> struct drm_nouveau_gem_pushbuf_push *push;
> + struct drm_nouveau_gem_pushbuf_reloc *reloc = NULL;
> struct drm_nouveau_gem_pushbuf_bo *bo;
> struct nouveau_channel *chan = NULL;
> struct validate_op op;
> struct nouveau_fence *fence = NULL;
> - int i, j, ret = 0, do_reloc = 0;
> + int i, j, ret = 0;
> + bool do_reloc = false;
>
> if (unlikely(!abi16))
> return -ENOMEM;
> @@ -755,7 +746,8 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data,
> }
>
> /* Validate buffer list */
> - ret = nouveau_gem_pushbuf_validate(chan, file_priv, bo, req->buffers,
> +revalidate:
> + ret = nouveau_gem_pushbuf_validate(chan, file_priv, bo,
> req->nr_buffers, &op, &do_reloc);
> if (ret) {
> if (ret != -ERESTARTSYS)
> @@ -765,7 +757,18 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data,
>
> /* Apply any relocations that are required */
> if (do_reloc) {
> - ret = nouveau_gem_pushbuf_reloc_apply(cli, req, bo);
> + if (!reloc) {
> + validate_fini(&op, chan, NULL, bo);
> + reloc = u_memcpya(req->relocs, req->nr_relocs, sizeof(*reloc));
> + if (IS_ERR(reloc)) {
> + ret = PTR_ERR(reloc);
> + goto out_prevalid;
> + }
> +
> + goto revalidate;
> + }
> +
> + ret = nouveau_gem_pushbuf_reloc_apply(cli, req, reloc, bo);
> if (ret) {
> NV_PRINTK(err, cli, "reloc apply: %d\n", ret);
> goto out;
> @@ -851,6 +854,22 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data,
> validate_fini(&op, chan, fence, bo);
> nouveau_fence_unref(&fence);
>
> + if (do_reloc) {
> + struct drm_nouveau_gem_pushbuf_bo __user *upbbo =
> + u64_to_user_ptr(req->buffers);
> +
> + for (i = 0; i < req->nr_buffers; i++) {
> + if (bo[i].presumed.valid)
> + continue;
> +
> + if (copy_to_user(&upbbo[i].presumed, &bo[i].presumed,
> + sizeof(bo[i].presumed))) {
> + ret = -EFAULT;
> + break;
> + }
> + }
> + u_free(reloc);
> + }
> out_prevalid:
> u_free(bo);
> u_free(push);
> --
> 2.23.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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