1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Memory Encryption Support Common Code |
4 | * |
5 | * Copyright (C) 2016 Advanced Micro Devices, Inc. |
6 | * |
7 | * Author: Tom Lendacky <thomas.lendacky@amd.com> |
8 | */ |
9 | |
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> |
16 | |
17 | #include <asm/sev.h> |
18 | |
19 | /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */ |
20 | bool force_dma_unencrypted(struct device *dev) |
21 | { |
22 | /* |
23 | * For SEV, all DMA must be to unencrypted addresses. |
24 | */ |
25 | if (cc_platform_has(attr: CC_ATTR_GUEST_MEM_ENCRYPT)) |
26 | return true; |
27 | |
28 | /* |
29 | * For SME, all DMA must be to unencrypted addresses if the |
30 | * device does not support DMA to addresses that include the |
31 | * encryption mask. |
32 | */ |
33 | if (cc_platform_has(attr: 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, |
36 | dev->bus_dma_limit); |
37 | |
38 | if (dma_dev_mask <= dma_enc_mask) |
39 | return true; |
40 | } |
41 | |
42 | return false; |
43 | } |
44 | |
45 | static void print_mem_encrypt_feature_info(void) |
46 | { |
47 | pr_info("Memory Encryption Features active: " ); |
48 | |
49 | switch (cc_vendor) { |
50 | case CC_VENDOR_INTEL: |
51 | pr_cont("Intel TDX\n" ); |
52 | break; |
53 | case CC_VENDOR_AMD: |
54 | pr_cont("AMD" ); |
55 | |
56 | /* Secure Memory Encryption */ |
57 | if (cc_platform_has(attr: CC_ATTR_HOST_MEM_ENCRYPT)) { |
58 | /* |
59 | * SME is mutually exclusive with any of the SEV |
60 | * features below. |
61 | */ |
62 | pr_cont(" SME\n" ); |
63 | return; |
64 | } |
65 | |
66 | /* Secure Encrypted Virtualization */ |
67 | if (cc_platform_has(attr: CC_ATTR_GUEST_MEM_ENCRYPT)) |
68 | pr_cont(" SEV" ); |
69 | |
70 | /* Encrypted Register State */ |
71 | if (cc_platform_has(attr: CC_ATTR_GUEST_STATE_ENCRYPT)) |
72 | pr_cont(" SEV-ES" ); |
73 | |
74 | /* Secure Nested Paging */ |
75 | if (cc_platform_has(attr: CC_ATTR_GUEST_SEV_SNP)) |
76 | pr_cont(" SEV-SNP" ); |
77 | |
78 | pr_cont("\n" ); |
79 | |
80 | sev_show_status(); |
81 | |
82 | break; |
83 | default: |
84 | pr_cont("Unknown\n" ); |
85 | } |
86 | } |
87 | |
88 | /* Architecture __weak replacement functions */ |
89 | void __init mem_encrypt_init(void) |
90 | { |
91 | if (!cc_platform_has(attr: CC_ATTR_MEM_ENCRYPT)) |
92 | return; |
93 | |
94 | /* Call into SWIOTLB to update the SWIOTLB DMA buffers */ |
95 | swiotlb_update_mem_attributes(); |
96 | |
97 | print_mem_encrypt_feature_info(); |
98 | } |
99 | |
100 | void __init mem_encrypt_setup_arch(void) |
101 | { |
102 | phys_addr_t total_mem = memblock_phys_mem_size(); |
103 | unsigned long size; |
104 | |
105 | if (!cc_platform_has(attr: CC_ATTR_GUEST_MEM_ENCRYPT)) |
106 | return; |
107 | |
108 | /* |
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. |
115 | * |
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. |
120 | * |
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% |
124 | */ |
125 | size = total_mem * 6 / 100; |
126 | size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G); |
127 | swiotlb_adjust_size(size); |
128 | |
129 | /* Set restricted memory access for virtio. */ |
130 | virtio_set_mem_acc_cb(func: virtio_require_restricted_mem_acc); |
131 | } |
132 | |