svga: flush buffers when mapping for reading

With host-side buffer copies (via SVGA3D_vgpu10_BufferCopy()) we have
to make sure any pending map-write operations are completed before reading
if the buffer is dirty.  Otherwise the ReadbackSubResource operation could
get stale data from the host buffer.

This allows the piglit arb_copy_buffer-subdata-sync test to pass when
we start using the SVGA3D_vgpu10_BufferCopy command.

v2: check the sbuf->dirty flag in the outer conditional, per Charmaine.

Acked-by: Roland Scheidegger <[email protected]>
Reviewed-by: Charmaine Lee <[email protected]>

1 files changed, 24 insertions, 13 deletions

diff --git a/src/gallium/drivers/svga/svga_resource_buffer.c b/src/gallium/drivers/svga/svga_resource_buffer.c
index 9ecb97509c2..a92a5c11904 100644
--- a/src/gallium/drivers/svga/svga_resource_buffer.c
+++ b/src/gallium/drivers/svga/svga_resource_buffer.c
@@ -96,25 +96,36 @@ svga_buffer_transfer_map(struct pipe_context *pipe,
    transfer->box = *box;
 
    if ((usage & PIPE_TRANSFER_READ) && sbuf->dirty) {
-      /* Only need to test for vgpu10 since only vgpu10 features (streamout,
-       * buffer copy) can modify buffers on the device.
+      enum pipe_error ret;
+
+      /* Host-side buffers can only be dirtied with vgpu10 features
+       * (streamout and buffer copy).
        */
-      if (svga_have_vgpu10(svga)) {
-         enum pipe_error ret;
-         assert(sbuf->handle);
-         ret = SVGA3D_vgpu10_ReadbackSubResource(svga->swc, sbuf->handle, 0);
-         if (ret != PIPE_OK) {
-            svga_context_flush(svga, NULL);
-            ret = SVGA3D_vgpu10_ReadbackSubResource(svga->swc, sbuf->handle, 0);
-            assert(ret == PIPE_OK);
-         }
+      assert(svga_have_vgpu10(svga));
 
-         svga->hud.num_readbacks++;
+      if (!sbuf->user) {
+         (void) svga_buffer_handle(svga, resource);
+      }
 
+      if (sbuf->dma.pending > 0) {
+         svga_buffer_upload_flush(svga, sbuf);
          svga_context_finish(svga);
+      }
+
+      assert(sbuf->handle);
 
-         sbuf->dirty = FALSE;
+      ret = SVGA3D_vgpu10_ReadbackSubResource(svga->swc, sbuf->handle, 0);
+      if (ret != PIPE_OK) {
+         svga_context_flush(svga, NULL);
+         ret = SVGA3D_vgpu10_ReadbackSubResource(svga->swc, sbuf->handle, 0);
+         assert(ret == PIPE_OK);
       }
+
+      svga->hud.num_readbacks++;
+
+      svga_context_finish(svga);
+
+      sbuf->dirty = FALSE;
    }
 
    if (usage & PIPE_TRANSFER_WRITE) {