6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Zack Rusin <[email protected]>

commit 4c08f01934ab67d1d283d5cbaa52b923abcfe4cd upstream.

Enable DMA mappings in vmwgfx after TTM has been fixed in commit
3bf3710e3718 ("drm/ttm: Add a generic TTM memcpy move for page-based iomem")

This enables full guest-backed memory support and in particular allows
usage of screen targets as the presentation mechanism.

Signed-off-by: Zack Rusin <[email protected]>
Reported-by: Ye Li <[email protected]>
Tested-by: Ye Li <[email protected]>
Fixes: 3b0d6458c705 ("drm/vmwgfx: Refuse DMA operation when SEV encryption is 
active")
Cc: Broadcom internal kernel review list <[email protected]>
Cc: [email protected]
Cc: <[email protected]> # v6.6+
Reviewed-by: Martin Krastev <[email protected]>
Link: 
https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -666,11 +666,12 @@ static int vmw_dma_select_mode(struct vm
                [vmw_dma_map_populate] = "Caching DMA mappings.",
                [vmw_dma_map_bind] = "Giving up DMA mappings early."};
 
-       /* TTM currently doesn't fully support SEV encryption. */
-       if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
-               return -EINVAL;
-
-       if (vmw_force_coherent)
+       /*
+        * When running with SEV we always want dma mappings, because
+        * otherwise ttm tt pool pages will bounce through swiotlb running
+        * out of available space.
+        */
+       if (vmw_force_coherent || cc_platform_has(CC_ATTR_MEM_ENCRYPT))
                dev_priv->map_mode = vmw_dma_alloc_coherent;
        else if (vmw_restrict_iommu)
                dev_priv->map_mode = vmw_dma_map_bind;


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