[PATCH 6.6 088/122] drm/vmwgfx: Enable DMA mappings with SEV

Greg Kroah-Hartman
2024-04-15T14:38:25Z

From: Zack Rusin <zack.rusin@broadcom.com>

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 <zack.rusin@broadcom.com>
Reported-by: Ye Li <ye.li@broadcom.com>
Tested-by: Ye Li <ye.li@broadcom.com>
Fixes: 3b0d6458c705 ("drm/vmwgfx: Refuse DMA operation when SEV encryption is active")
Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.6+
Reviewed-by: Martin Krastev <martin.krastev@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240408022802.358641-1-zack.rusin@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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;