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