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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Confidential Computing Platform Capability checks
- *
- * Copyright (C) 2021 Advanced Micro Devices, Inc.
- *
- * Author: Tom Lendacky <thomas.lendacky@amd.com>
- */
- #include <linux/export.h>
- #include <linux/cc_platform.h>
- #include <linux/mem_encrypt.h>
- #include <asm/processor.h>
- static bool __maybe_unused intel_cc_platform_has(enum cc_attr attr)
- {
- #ifdef CONFIG_INTEL_TDX_GUEST
- return false;
- #else
- return false;
- #endif
- }
- /*
- * SME and SEV are very similar but they are not the same, so there are
- * times that the kernel will need to distinguish between SME and SEV. The
- * cc_platform_has() function is used for this. When a distinction isn't
- * needed, the CC_ATTR_MEM_ENCRYPT attribute can be used.
- *
- * The trampoline code is a good example for this requirement. Before
- * paging is activated, SME will access all memory as decrypted, but SEV
- * will access all memory as encrypted. So, when APs are being brought
- * up under SME the trampoline area cannot be encrypted, whereas under SEV
- * the trampoline area must be encrypted.
- */
- static bool amd_cc_platform_has(enum cc_attr attr)
- {
- #ifdef CONFIG_AMD_MEM_ENCRYPT
- switch (attr) {
- case CC_ATTR_MEM_ENCRYPT:
- return sme_me_mask;
- case CC_ATTR_HOST_MEM_ENCRYPT:
- return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED);
- case CC_ATTR_GUEST_MEM_ENCRYPT:
- return sev_status & MSR_AMD64_SEV_ENABLED;
- case CC_ATTR_GUEST_STATE_ENCRYPT:
- return sev_status & MSR_AMD64_SEV_ES_ENABLED;
- default:
- return false;
- }
- #else
- return false;
- #endif
- }
- bool cc_platform_has(enum cc_attr attr)
- {
- if (sme_me_mask)
- return amd_cc_platform_has(attr);
- return false;
- }
- EXPORT_SYMBOL_GPL(cc_platform_has);
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