1 // SPDX-License-Identifier: GPL-2.0-only
3 * Memory Encryption Support Common Code
5 * Copyright (C) 2016 Advanced Micro Devices, Inc.
7 * Author: Tom Lendacky <thomas.lendacky@amd.com>
10 #include <linux/dma-direct.h>
11 #include <linux/dma-mapping.h>
12 #include <linux/swiotlb.h>
13 #include <linux/cc_platform.h>
14 #include <linux/mem_encrypt.h>
15 #include <linux/virtio_anchor.h>
19 /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
20 bool force_dma_unencrypted(struct device *dev)
23 * For SEV, all DMA must be to unencrypted addresses.
25 if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
29 * For SME, all DMA must be to unencrypted addresses if the
30 * device does not support DMA to addresses that include the
33 if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
34 u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask));
35 u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask,
38 if (dma_dev_mask <= dma_enc_mask)
45 static void print_mem_encrypt_feature_info(void)
47 pr_info("Memory Encryption Features active: ");
51 pr_cont("Intel TDX\n");
56 /* Secure Memory Encryption */
57 if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
59 * SME is mutually exclusive with any of the SEV
66 /* Secure Encrypted Virtualization */
67 if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
70 /* Encrypted Register State */
71 if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
74 /* Secure Nested Paging */
75 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
88 /* Architecture __weak replacement functions */
89 void __init mem_encrypt_init(void)
91 if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT))
94 /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
95 swiotlb_update_mem_attributes();
97 print_mem_encrypt_feature_info();
100 void __init mem_encrypt_setup_arch(void)
102 phys_addr_t total_mem = memblock_phys_mem_size();
105 if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
109 * For SEV and TDX, all DMA has to occur via shared/unencrypted pages.
110 * Kernel uses SWIOTLB to make this happen without changing device
111 * drivers. However, depending on the workload being run, the
112 * default 64MB of SWIOTLB may not be enough and SWIOTLB may
113 * run out of buffers for DMA, resulting in I/O errors and/or
114 * performance degradation especially with high I/O workloads.
116 * Adjust the default size of SWIOTLB using a percentage of guest
117 * memory for SWIOTLB buffers. Also, as the SWIOTLB bounce buffer
118 * memory is allocated from low memory, ensure that the adjusted size
119 * is within the limits of low available memory.
121 * The percentage of guest memory used here for SWIOTLB buffers
122 * is more of an approximation of the static adjustment which
123 * 64MB for <1G, and ~128M to 256M for 1G-to-4G, i.e., the 6%
125 size = total_mem * 6 / 100;
126 size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G);
127 swiotlb_adjust_size(size);
129 /* Set restricted memory access for virtio. */
130 virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);