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>

4 files changed, 30 insertions, 1 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
index 37a81925b158..825ebe3d89d5 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
@@ -48,6 +48,15 @@ struct ttm_placement vmw_vram_placement = {
         .busy_placement = &vram_placement_flags
 };
 
+struct ttm_placement vmw_vram_sys_placement = {
+        .fpfn = 0,
+        .lpfn = 0,
+        .num_placement = 1,
+        .placement = &vram_placement_flags,
+        .num_busy_placement = 1,
+        .busy_placement = &sys_placement_flags
+};
+
 struct ttm_placement vmw_vram_ne_placement = {
         .fpfn = 0,
         .lpfn = 0,
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 7532b9b47eec..50529a7f06fb 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -404,6 +404,7 @@ extern int vmw_mmap(struct file *filp, struct vm_area_struct *vma);
 
 extern struct ttm_placement vmw_vram_placement;
 extern struct ttm_placement vmw_vram_ne_placement;
+extern struct ttm_placement vmw_vram_sys_placement;
 extern struct ttm_placement vmw_sys_placement;
 extern struct ttm_bo_driver vmw_bo_driver;
 extern int vmw_dma_quiescent(struct drm_device *dev);
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;
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index e0878077e8aa..e01db120efff 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -872,7 +872,7 @@ int vmw_dmabuf_alloc_ioctl(struct drm_device *dev, void *data,
         }
 
         ret = vmw_dmabuf_init(dev_priv, &vmw_user_bo->dma, req->size,
-                              &vmw_vram_placement, true,
+                              &vmw_vram_sys_placement, true,
                               &vmw_user_dmabuf_destroy);
         if (unlikely(ret != 0))
                 return ret;