1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Confidential Computing Platform Capability checks 4 * 5 * Copyright (C) 2021 Advanced Micro Devices, Inc. 6 * 7 * Author: Tom Lendacky <thomas.lendacky@amd.com> 8 */ 9 10 #include <linux/export.h> 11 #include <linux/cc_platform.h> 12 13 #include <asm/coco.h> 14 #include <asm/processor.h> 15 16 static enum cc_vendor vendor __ro_after_init; 17 static u64 cc_mask __ro_after_init; 18 19 static bool intel_cc_platform_has(enum cc_attr attr) 20 { 21 switch (attr) { 22 case CC_ATTR_GUEST_UNROLL_STRING_IO: 23 case CC_ATTR_HOTPLUG_DISABLED: 24 case CC_ATTR_GUEST_MEM_ENCRYPT: 25 case CC_ATTR_MEM_ENCRYPT: 26 return true; 27 default: 28 return false; 29 } 30 } 31 32 /* 33 * SME and SEV are very similar but they are not the same, so there are 34 * times that the kernel will need to distinguish between SME and SEV. The 35 * cc_platform_has() function is used for this. When a distinction isn't 36 * needed, the CC_ATTR_MEM_ENCRYPT attribute can be used. 37 * 38 * The trampoline code is a good example for this requirement. Before 39 * paging is activated, SME will access all memory as decrypted, but SEV 40 * will access all memory as encrypted. So, when APs are being brought 41 * up under SME the trampoline area cannot be encrypted, whereas under SEV 42 * the trampoline area must be encrypted. 43 */ 44 static bool amd_cc_platform_has(enum cc_attr attr) 45 { 46 #ifdef CONFIG_AMD_MEM_ENCRYPT 47 switch (attr) { 48 case CC_ATTR_MEM_ENCRYPT: 49 return sme_me_mask; 50 51 case CC_ATTR_HOST_MEM_ENCRYPT: 52 return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED); 53 54 case CC_ATTR_GUEST_MEM_ENCRYPT: 55 return sev_status & MSR_AMD64_SEV_ENABLED; 56 57 case CC_ATTR_GUEST_STATE_ENCRYPT: 58 return sev_status & MSR_AMD64_SEV_ES_ENABLED; 59 60 /* 61 * With SEV, the rep string I/O instructions need to be unrolled 62 * but SEV-ES supports them through the #VC handler. 63 */ 64 case CC_ATTR_GUEST_UNROLL_STRING_IO: 65 return (sev_status & MSR_AMD64_SEV_ENABLED) && 66 !(sev_status & MSR_AMD64_SEV_ES_ENABLED); 67 68 case CC_ATTR_GUEST_SEV_SNP: 69 return sev_status & MSR_AMD64_SEV_SNP_ENABLED; 70 71 default: 72 return false; 73 } 74 #else 75 return false; 76 #endif 77 } 78 79 static bool hyperv_cc_platform_has(enum cc_attr attr) 80 { 81 return attr == CC_ATTR_GUEST_MEM_ENCRYPT; 82 } 83 84 bool cc_platform_has(enum cc_attr attr) 85 { 86 switch (vendor) { 87 case CC_VENDOR_AMD: 88 return amd_cc_platform_has(attr); 89 case CC_VENDOR_INTEL: 90 return intel_cc_platform_has(attr); 91 case CC_VENDOR_HYPERV: 92 return hyperv_cc_platform_has(attr); 93 default: 94 return false; 95 } 96 } 97 EXPORT_SYMBOL_GPL(cc_platform_has); 98 99 u64 cc_mkenc(u64 val) 100 { 101 /* 102 * Both AMD and Intel use a bit in the page table to indicate 103 * encryption status of the page. 104 * 105 * - for AMD, bit *set* means the page is encrypted 106 * - for Intel *clear* means encrypted. 107 */ 108 switch (vendor) { 109 case CC_VENDOR_AMD: 110 return val | cc_mask; 111 case CC_VENDOR_INTEL: 112 return val & ~cc_mask; 113 default: 114 return val; 115 } 116 } 117 118 u64 cc_mkdec(u64 val) 119 { 120 /* See comment in cc_mkenc() */ 121 switch (vendor) { 122 case CC_VENDOR_AMD: 123 return val & ~cc_mask; 124 case CC_VENDOR_INTEL: 125 return val | cc_mask; 126 default: 127 return val; 128 } 129 } 130 EXPORT_SYMBOL_GPL(cc_mkdec); 131 132 __init void cc_set_vendor(enum cc_vendor v) 133 { 134 vendor = v; 135 } 136 137 __init void cc_set_mask(u64 mask) 138 { 139 cc_mask = mask; 140 } 141