[Mesa-dev] [PATCH] radeonsi: add missing initialization for userptr buffers

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

Fix the accounting for memory usage of userptr buffers, which has been wrong
forever (or at least for a long time).

Also initialize flags. Without this initialization, the sparse buffer flag
might end up being set, which leads to staging buffers being used unnecessarily
(and incorrectly) in transfers to or from userptr buffers.

This works around VM faults that occur with the radeon kernel module when
running piglit ./bin/amd_pinned_memory decrement-offset map-buffer -auto
(but it's actually also needed for correctness anyway, since the
GL_AMD_pinned_memory spec clarifies that staging buffers shouldn't be used).

Fixes: e077c5fe6579 ("gallium/radeon: transfers and invalidation for sparse buffers")
Reported-by: Michel Dänzer <michel.daenzer at amd.com>
--
So, those VM faults shouldn't happen anyway, even when the unnecessary transfers
occur. We do add the buffer to the buffer list, and amdgpu never showed VM faults,
so this suggests that there's still a bug in the radeon kernel module.
---
 src/gallium/drivers/radeon/r600_buffer_common.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/gallium/drivers/radeon/r600_buffer_common.c b/src/gallium/drivers/radeon/r600_buffer_common.c
index 0e93404..b2289e2 100644
--- a/src/gallium/drivers/radeon/r600_buffer_common.c
+++ b/src/gallium/drivers/radeon/r600_buffer_common.c
@@ -605,27 +605,31 @@ struct pipe_resource *r600_aligned_buffer_create(struct pipe_screen *screen,
 struct pipe_resource *
 r600_buffer_from_user_memory(struct pipe_screen *screen,
 			     const struct pipe_resource *templ,
 			     void *user_memory)
 {
 	struct r600_common_screen *rscreen = (struct r600_common_screen*)screen;
 	struct radeon_winsys *ws = rscreen->ws;
 	struct r600_resource *rbuffer = r600_alloc_buffer_struct(screen, templ);
 
 	rbuffer->domains = RADEON_DOMAIN_GTT;
+	rbuffer->flags = 0;
 	util_range_add(&rbuffer->valid_buffer_range, 0, templ->width0);
 
 	/* Convert a user pointer to a buffer. */
 	rbuffer->buf = ws->buffer_from_ptr(ws, user_memory, templ->width0);
 	if (!rbuffer->buf) {
 		FREE(rbuffer);
 		return NULL;
 	}
 
 	if (rscreen->info.has_virtual_memory)
 		rbuffer->gpu_address =
 			ws->buffer_get_virtual_address(rbuffer->buf);
 	else
 		rbuffer->gpu_address = 0;
 
+	rbuffer->vram_usage = 0;
+	rbuffer->gart_usage = templ->width0;
+
 	return &rbuffer->b.b;
 }
-- 
2.9.3