[Mesa-dev] [PATCH v2] nvc0: ensure that pushbuf keeps ref to old text/tls bos

[Ilia Mirkin]

If we free the bo, then the PTE may get deallocated immediately. We have
to make sure that the submission includes a ref to the old bo so that it
remains mapped for the duration of the command execution.

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
---

v1 -> v2:
  Ben pointed out that not deleting the BO is not enough -- we have to
  actually ref it to the pushbuf, otherwise it could still get kicked
  out of VRAM.

  I happened to notice that the TLS logic suffers from a similar issue,
  although in practice it doesn't matter since we never resize TLS.

 src/gallium/drivers/nouveau/nvc0/nvc0_screen.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c b/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
index 02562dd4eb2..cac4bb89271 100644
--- a/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
+++ b/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
@@ -741,6 +741,13 @@ nvc0_screen_resize_tls_area(struct nvc0_screen *screen,
                         NULL, &bo);
    if (ret)
       return ret;
+
+   /* Make sure that the pushbuf has acquired a reference to the old tls
+    * segment, as it may have commands that will reference it.
+    */
+   if (screen->tls)
+      PUSH_REFN(screen->base.pushbuf, screen->tls,
+                NV_VRAM_DOMAIN(&screen->base) | NOUVEAU_BO_RDWR);
    nouveau_bo_ref(NULL, &screen->tls);
    screen->tls = bo;
    return 0;
@@ -758,6 +765,12 @@ nvc0_screen_resize_text_area(struct nvc0_screen *screen, uint64_t size)
    if (ret)
       return ret;
 
+   /* Make sure that the pushbuf has acquired a reference to the old text
+    * segment, as it may have commands that will reference it.
+    */
+   if (screen->text)
+      PUSH_REFN(push, screen->text,
+                NV_VRAM_DOMAIN(&screen->base) | NOUVEAU_BO_RD);
    nouveau_bo_ref(NULL, &screen->text);
    screen->text = bo;
 
-- 
2.13.6