drm/vmwgfx: Optimize memory footprint for DMA buffers.

Use VRAM whenever there is free space for DMA buffers,
but use system GMR memory if using VRAM would cause an eviction.

This significantly reduces the guest system memory usage for
VMs with a large amount of VRAM allocated.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index 2e92da567403..d69caf92ffe7 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -490,10 +490,29 @@ static int vmw_validate_single_buffer(struct vmw_private *dev_priv,
         if (vmw_dmabuf_gmr(bo) != SVGA_GMR_NULL)
                 return 0;
 
+        /**
+         * Put BO in VRAM, only if there is space.
+         */
+
+        ret = ttm_bo_validate(bo, &vmw_vram_sys_placement, true, false);
+        if (unlikely(ret == -ERESTARTSYS))
+                return ret;
+
+        /**
+         * Otherwise, set it up as GMR.
+         */
+
+        if (vmw_dmabuf_gmr(bo) != SVGA_GMR_NULL)
+                return 0;
+
         ret = vmw_gmr_bind(dev_priv, bo);
         if (likely(ret == 0 || ret == -ERESTARTSYS))
                 return ret;
 
+        /**
+         * If that failed, try VRAM again, this time evicting
+         * previous contents.
+         */
 
         ret = ttm_bo_validate(bo, &vmw_vram_placement, true, false);
         return ret;