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 #include <linux/mem_encrypt.h> 13 14 #include <asm/processor.h> 15 intel_cc_platform_has(enum cc_attr attr)16static bool __maybe_unused intel_cc_platform_has(enum cc_attr attr) 17 { 18 #ifdef CONFIG_INTEL_TDX_GUEST 19 return false; 20 #else 21 return false; 22 #endif 23 } 24 25 /* 26 * SME and SEV are very similar but they are not the same, so there are 27 * times that the kernel will need to distinguish between SME and SEV. The 28 * cc_platform_has() function is used for this. When a distinction isn't 29 * needed, the CC_ATTR_MEM_ENCRYPT attribute can be used. 30 * 31 * The trampoline code is a good example for this requirement. Before 32 * paging is activated, SME will access all memory as decrypted, but SEV 33 * will access all memory as encrypted. So, when APs are being brought 34 * up under SME the trampoline area cannot be encrypted, whereas under SEV 35 * the trampoline area must be encrypted. 36 */ amd_cc_platform_has(enum cc_attr attr)37static bool amd_cc_platform_has(enum cc_attr attr) 38 { 39 #ifdef CONFIG_AMD_MEM_ENCRYPT 40 switch (attr) { 41 case CC_ATTR_MEM_ENCRYPT: 42 return sme_me_mask; 43 44 case CC_ATTR_HOST_MEM_ENCRYPT: 45 return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED); 46 47 case CC_ATTR_GUEST_MEM_ENCRYPT: 48 return sev_status & MSR_AMD64_SEV_ENABLED; 49 50 case CC_ATTR_GUEST_STATE_ENCRYPT: 51 return sev_status & MSR_AMD64_SEV_ES_ENABLED; 52 53 default: 54 return false; 55 } 56 #else 57 return false; 58 #endif 59 } 60 61 cc_platform_has(enum cc_attr attr)62bool cc_platform_has(enum cc_attr attr) 63 { 64 if (sme_me_mask) 65 return amd_cc_platform_has(attr); 66 67 return false; 68 } 69 EXPORT_SYMBOL_GPL(cc_platform_has); 70