[RFC PATCH v1 12/28] x86: DMA support for SEV memory encryption

@@ -173,8 +173,52 @@ void __init sme_early_init(void)
 	/* Update the protection map with memory encryption mask */
 	for (i = 0; i < ARRAY_SIZE(protection_map); i++)
 		protection_map[i] = __pgprot(pgprot_val(protection_map[i]) | sme_me_mask);
+
+	if (sev_active)
+		swiotlb_force = 1;
 }
 
+static void *sme_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		       gfp_t gfp, unsigned long attrs)
+{
+	void *vaddr;
+
+	vaddr = x86_swiotlb_alloc_coherent(dev, size, dma_handle, gfp, attrs);
+	if (!vaddr)
+		return NULL;
+
+	/* Clear the SME encryption bit for DMA use */
+	sme_set_mem_dec(vaddr, size);
+
+	/* Remove the encryption bit from the DMA address */
+	*dma_handle &= ~sme_me_mask;
+
+	return vaddr;
+}
+
+static void sme_free(struct device *dev, size_t size, void *vaddr,
+		     dma_addr_t dma_handle, unsigned long attrs)
+{
+	/* Set the SME encryption bit for re-use as encrypted */
+	sme_set_mem_enc(vaddr, size);
+
+	x86_swiotlb_free_coherent(dev, size, vaddr, dma_handle, attrs);
+}
+
+static struct dma_map_ops sme_dma_ops = {
+	.alloc                  = sme_alloc,
+	.free                   = sme_free,
+	.map_page               = swiotlb_map_page,
+	.unmap_page             = swiotlb_unmap_page,
+	.map_sg                 = swiotlb_map_sg_attrs,
+	.unmap_sg               = swiotlb_unmap_sg_attrs,
+	.sync_single_for_cpu    = swiotlb_sync_single_for_cpu,
+	.sync_single_for_device = swiotlb_sync_single_for_device,
+	.sync_sg_for_cpu        = swiotlb_sync_sg_for_cpu,
+	.sync_sg_for_device     = swiotlb_sync_sg_for_device,
+	.mapping_error          = swiotlb_dma_mapping_error,
+};
+
 /* Architecture __weak replacement functions */
 void __init mem_encrypt_init(void)
 {

@@ -184,6 +228,10 @@ void __init mem_encrypt_init(void)
 	/* Make SWIOTLB use an unencrypted DMA area */
 	swiotlb_clear_encryption();
 
+	/* Use SEV DMA operations if SEV is active */
+	if (sev_active)
+		dma_ops = &sme_dma_ops;
+
 	pr_info("memory encryption active\n");
 }
 

--