[Nouveau] Small patch for nv50_vbo.c

[Ilia Mirkin]

This isn't meant to fix applications, it's meant to limit the range of
access to the buffer, for robustness/etc reasons. One would have to
look very carefully, as all this logic is rather tricky.

On Mon, Oct 19, 2020 at 4:07 AM Andrew Randrianasulu
<randrianasulu at gmail.com> wrote:
>
> Hi all!
>
> I saw TODO comment in nv50_vbo.c and decided to look at similar file, nvc0_vbo.c. I copied those two lines into nv50 with slight name change (nvc0->nv50) and apparently it doesn't fix any OpenGL app I have, but does not broke them further (I have compute pacthes currently applied, so some breakage expected).
>
> diff --git a/src/gallium/drivers/nouveau/nv50/nv50_vbo.c b/src/gallium/drivers/nouveau/nv50/nv50_vbo.c
> index 8d1c8c7665b..29b63a525aa 100644
> --- a/src/gallium/drivers/nouveau/nv50/nv50_vbo.c
> +++ b/src/gallium/drivers/nouveau/nv50/nv50_vbo.c
> @@ -189,8 +189,12 @@ nv50_user_vbuf_range(struct nv50_context *nv50, unsigned vbi,
>     assert(vbi < PIPE_MAX_ATTRIBS);
>     if (unlikely(nv50->vertex->instance_bufs & (1 << vbi))) {
>        /* TODO: use min and max instance divisor to get a proper range */
> -      *base = 0;
> -      *size = nv50->vtxbuf[vbi].buffer.resource->width0;
> +      const uint32_t div = nv50->vertex->min_instance_div[vbi];
> +      *base = nv50->instance_off * nv50->vtxbuf[vbi].stride;
> +      *size = (nv50->instance_max / div) * nv50->vtxbuf[vbi].stride +
> +         nv50->vertex->vb_access_size[vbi];
> +//      *base = 0;
> +//      *size = nv50->vtxbuf[vbi].buffer.resource->width0;
>     } else {
>        /* NOTE: if there are user buffers, we *must* have index bounds */
>        assert(nv50->vb_elt_limit != ~0);
>
> Does this look correct?
>
>
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