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
 16static enum cc_vendor vendor __ro_after_init;
 17static u64 cc_mask __ro_after_init;
 18
 19static 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 */
 44static 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
 79static bool hyperv_cc_platform_has(enum cc_attr attr)
 80{
 81	return attr == CC_ATTR_GUEST_MEM_ENCRYPT;
 82}
 83
 84bool 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}
 97EXPORT_SYMBOL_GPL(cc_platform_has);
 98
 99u64 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
118u64 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}
130EXPORT_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}