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