drm/amdgpu: Fail to load on RAVEN if SME is active

Due to hardware bugs, scatter/gather display on raven requires
a 1:1 IOMMU mapping, however, SME (System Memory Encryption)
requires an indirect IOMMU mapping because the encryption bit
is beyond the DMA mask of the chip.  As such, the two are
incompatible.
Acked-by: NJoerg Roedel <jroedel@suse.de>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Acked-by: NFelix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

@@ -1101,6 +1101,16 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
 		return -ENODEV;
 	}
 
+	/* Due to hardware bugs, S/G Display on raven requires a 1:1 IOMMU mapping,
+	 * however, SME requires an indirect IOMMU mapping because the encryption
+	 * bit is beyond the DMA mask of the chip.
+	 */
+	if (mem_encrypt_active() && ((flags & AMD_ASIC_MASK) == CHIP_RAVEN)) {
+		dev_info(&pdev->dev,
+			 "SME is not compatible with RAVEN\n");
+		return -ENOTSUPP;
+	}
+
 #ifdef CONFIG_DRM_AMDGPU_SI
 	if (!amdgpu_si_support) {
 		switch (flags & AMD_ASIC_MASK) {