1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/tboot.h> 3 4 #include <asm/cpufeature.h> 5 #include <asm/msr-index.h> 6 #include <asm/processor.h> 7 #include <asm/vmx.h> 8 #include "cpu.h" 9 10 #undef pr_fmt 11 #define pr_fmt(fmt) "x86/cpu: " fmt 12 13 #ifdef CONFIG_X86_VMX_FEATURE_NAMES 14 enum vmx_feature_leafs { 15 MISC_FEATURES = 0, 16 PRIMARY_CTLS, 17 SECONDARY_CTLS, 18 NR_VMX_FEATURE_WORDS, 19 }; 20 21 #define VMX_F(x) BIT(VMX_FEATURE_##x & 0x1f) 22 23 static void init_vmx_capabilities(struct cpuinfo_x86 *c) 24 { 25 u32 supported, funcs, ept, vpid, ign; 26 27 BUILD_BUG_ON(NVMXINTS != NR_VMX_FEATURE_WORDS); 28 29 /* 30 * The high bits contain the allowed-1 settings, i.e. features that can 31 * be turned on. The low bits contain the allowed-0 settings, i.e. 32 * features that can be turned off. Ignore the allowed-0 settings, 33 * if a feature can be turned on then it's supported. 34 * 35 * Use raw rdmsr() for primary processor controls and pin controls MSRs 36 * as they exist on any CPU that supports VMX, i.e. we want the WARN if 37 * the RDMSR faults. 38 */ 39 rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, ign, supported); 40 c->vmx_capability[PRIMARY_CTLS] = supported; 41 42 rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS2, &ign, &supported); 43 c->vmx_capability[SECONDARY_CTLS] = supported; 44 45 rdmsr(MSR_IA32_VMX_PINBASED_CTLS, ign, supported); 46 rdmsr_safe(MSR_IA32_VMX_VMFUNC, &ign, &funcs); 47 48 /* 49 * Except for EPT+VPID, which enumerates support for both in a single 50 * MSR, low for EPT, high for VPID. 51 */ 52 rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP, &ept, &vpid); 53 54 /* Pin, EPT, VPID and VM-Func are merged into a single word. */ 55 WARN_ON_ONCE(supported >> 16); 56 WARN_ON_ONCE(funcs >> 4); 57 c->vmx_capability[MISC_FEATURES] = (supported & 0xffff) | 58 ((vpid & 0x1) << 16) | 59 ((funcs & 0xf) << 28); 60 61 /* EPT bits are full on scattered and must be manually handled. */ 62 if (ept & VMX_EPT_EXECUTE_ONLY_BIT) 63 c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_EXECUTE_ONLY); 64 if (ept & VMX_EPT_AD_BIT) 65 c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_AD); 66 if (ept & VMX_EPT_1GB_PAGE_BIT) 67 c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_1GB); 68 69 /* Synthetic APIC features that are aggregates of multiple features. */ 70 if ((c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) && 71 (c->vmx_capability[SECONDARY_CTLS] & VMX_F(VIRT_APIC_ACCESSES))) 72 c->vmx_capability[MISC_FEATURES] |= VMX_F(FLEXPRIORITY); 73 74 if ((c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) && 75 (c->vmx_capability[SECONDARY_CTLS] & VMX_F(APIC_REGISTER_VIRT)) && 76 (c->vmx_capability[SECONDARY_CTLS] & VMX_F(VIRT_INTR_DELIVERY)) && 77 (c->vmx_capability[MISC_FEATURES] & VMX_F(POSTED_INTR))) 78 c->vmx_capability[MISC_FEATURES] |= VMX_F(APICV); 79 80 /* Set the synthetic cpufeatures to preserve /proc/cpuinfo's ABI. */ 81 if (c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) 82 set_cpu_cap(c, X86_FEATURE_TPR_SHADOW); 83 if (c->vmx_capability[MISC_FEATURES] & VMX_F(FLEXPRIORITY)) 84 set_cpu_cap(c, X86_FEATURE_FLEXPRIORITY); 85 if (c->vmx_capability[MISC_FEATURES] & VMX_F(VIRTUAL_NMIS)) 86 set_cpu_cap(c, X86_FEATURE_VNMI); 87 if (c->vmx_capability[SECONDARY_CTLS] & VMX_F(EPT)) 88 set_cpu_cap(c, X86_FEATURE_EPT); 89 if (c->vmx_capability[MISC_FEATURES] & VMX_F(EPT_AD)) 90 set_cpu_cap(c, X86_FEATURE_EPT_AD); 91 if (c->vmx_capability[MISC_FEATURES] & VMX_F(VPID)) 92 set_cpu_cap(c, X86_FEATURE_VPID); 93 } 94 #endif /* CONFIG_X86_VMX_FEATURE_NAMES */ 95 96 void init_ia32_feat_ctl(struct cpuinfo_x86 *c) 97 { 98 bool tboot = tboot_enabled(); 99 u64 msr; 100 101 if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) { 102 clear_cpu_cap(c, X86_FEATURE_VMX); 103 return; 104 } 105 106 if (msr & FEAT_CTL_LOCKED) 107 goto update_caps; 108 109 /* 110 * Ignore whatever value BIOS left in the MSR to avoid enabling random 111 * features or faulting on the WRMSR. 112 */ 113 msr = FEAT_CTL_LOCKED; 114 115 /* 116 * Enable VMX if and only if the kernel may do VMXON at some point, 117 * i.e. KVM is enabled, to avoid unnecessarily adding an attack vector 118 * for the kernel, e.g. using VMX to hide malicious code. 119 */ 120 if (cpu_has(c, X86_FEATURE_VMX) && IS_ENABLED(CONFIG_KVM_INTEL)) { 121 msr |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX; 122 123 if (tboot) 124 msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX; 125 } 126 127 wrmsrl(MSR_IA32_FEAT_CTL, msr); 128 129 update_caps: 130 set_cpu_cap(c, X86_FEATURE_MSR_IA32_FEAT_CTL); 131 132 if (!cpu_has(c, X86_FEATURE_VMX)) 133 return; 134 135 if ( (tboot && !(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX)) || 136 (!tboot && !(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX))) { 137 if (IS_ENABLED(CONFIG_KVM_INTEL)) 138 pr_err_once("VMX (%s TXT) disabled by BIOS\n", 139 tboot ? "inside" : "outside"); 140 clear_cpu_cap(c, X86_FEATURE_VMX); 141 } else { 142 #ifdef CONFIG_X86_VMX_FEATURE_NAMES 143 init_vmx_capabilities(c); 144 #endif 145 } 146 } 147