arch/x86/mm/mem_encrypt.c

   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
  16 /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
  17 bool force_dma_unencrypted(struct device *dev)
  18 {
  19         /*
  20          * For SEV, all DMA must be to unencrypted addresses.
  21          */
  22         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
  23                 return true;
  24
  25         /*
  26          * For SME, all DMA must be to unencrypted addresses if the
  27          * device does not support DMA to addresses that include the
  28          * encryption mask.
  29          */
  30         if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
  31                 u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask));
  32                 u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask,
  33                                                 dev->bus_dma_limit);
  34
  35                 if (dma_dev_mask <= dma_enc_mask)
  36                         return true;
  37         }
  38
  39         return false;
  40 }
  41
  42 static void print_mem_encrypt_feature_info(void)
  43 {
  44         pr_info("Memory Encryption Features active:");
  45
  46         if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {
  47                 pr_cont(" Intel TDX\n");
  48                 return;
  49         }
  50
  51         pr_cont(" AMD");
  52
  53         /* Secure Memory Encryption */
  54         if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
  55                 /*
  56                  * SME is mutually exclusive with any of the SEV
  57                  * features below.
  58                  */
  59                 pr_cont(" SME\n");
  60                 return;
  61         }
  62
  63         /* Secure Encrypted Virtualization */
  64         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
  65                 pr_cont(" SEV");
  66
  67         /* Encrypted Register State */
  68         if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
  69                 pr_cont(" SEV-ES");
  70
  71         /* Secure Nested Paging */
  72         if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
  73                 pr_cont(" SEV-SNP");
  74
  75         pr_cont("\n");
  76 }
  77
  78 /* Architecture __weak replacement functions */
  79 void __init mem_encrypt_init(void)
  80 {
  81         if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT))
  82                 return;
  83
  84         /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
  85         swiotlb_update_mem_attributes();
  86
  87         print_mem_encrypt_feature_info();
  88 }