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 return false; 22 } 23 24 /* 25 * SME and SEV are very similar but they are not the same, so there are 26 * times that the kernel will need to distinguish between SME and SEV. The 27 * cc_platform_has() function is used for this. When a distinction isn't 28 * needed, the CC_ATTR_MEM_ENCRYPT attribute can be used. 29 * 30 * The trampoline code is a good example for this requirement. Before 31 * paging is activated, SME will access all memory as decrypted, but SEV 32 * will access all memory as encrypted. So, when APs are being brought 33 * up under SME the trampoline area cannot be encrypted, whereas under SEV 34 * the trampoline area must be encrypted. 35 */ 36 static bool amd_cc_platform_has(enum cc_attr attr) 37 { 38 #ifdef CONFIG_AMD_MEM_ENCRYPT 39 switch (attr) { 40 case CC_ATTR_MEM_ENCRYPT: 41 return sme_me_mask; 42 43 case CC_ATTR_HOST_MEM_ENCRYPT: 44 return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED); 45 46 case CC_ATTR_GUEST_MEM_ENCRYPT: 47 return sev_status & MSR_AMD64_SEV_ENABLED; 48 49 case CC_ATTR_GUEST_STATE_ENCRYPT: 50 return sev_status & MSR_AMD64_SEV_ES_ENABLED; 51 52 /* 53 * With SEV, the rep string I/O instructions need to be unrolled 54 * but SEV-ES supports them through the #VC handler. 55 */ 56 case CC_ATTR_GUEST_UNROLL_STRING_IO: 57 return (sev_status & MSR_AMD64_SEV_ENABLED) && 58 !(sev_status & MSR_AMD64_SEV_ES_ENABLED); 59 60 default: 61 return false; 62 } 63 #else 64 return false; 65 #endif 66 } 67 68 static bool hyperv_cc_platform_has(enum cc_attr attr) 69 { 70 return attr == CC_ATTR_GUEST_MEM_ENCRYPT; 71 } 72 73 bool cc_platform_has(enum cc_attr attr) 74 { 75 switch (vendor) { 76 case CC_VENDOR_AMD: 77 return amd_cc_platform_has(attr); 78 case CC_VENDOR_INTEL: 79 return intel_cc_platform_has(attr); 80 case CC_VENDOR_HYPERV: 81 return hyperv_cc_platform_has(attr); 82 default: 83 return false; 84 } 85 } 86 EXPORT_SYMBOL_GPL(cc_platform_has); 87 88 u64 cc_mkenc(u64 val) 89 { 90 switch (vendor) { 91 case CC_VENDOR_AMD: 92 return val | cc_mask; 93 default: 94 return val; 95 } 96 } 97 98 u64 cc_mkdec(u64 val) 99 { 100 switch (vendor) { 101 case CC_VENDOR_AMD: 102 return val & ~cc_mask; 103 default: 104 return val; 105 } 106 } 107 EXPORT_SYMBOL_GPL(cc_mkdec); 108 109 __init void cc_set_vendor(enum cc_vendor v) 110 { 111 vendor = v; 112 } 113 114 __init void cc_set_mask(u64 mask) 115 { 116 cc_mask = mask; 117 } 118