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
|
From 8f8f17abbbabcff7ebf353b62bbcfb414f83d77e Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Wed, 25 Apr 2018 22:04:25 -0400
Subject: [PATCH 33/93] x86/KVM/VMX: Expose SPEC_CTRL Bit(2) to the guest
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
commit da39556f66f5cfe8f9c989206974f1cb16ca5d7c upstream
Expose the CPUID.7.EDX[31] bit to the guest, and also guard against various
combinations of SPEC_CTRL MSR values.
The handling of the MSR (to take into account the host value of SPEC_CTRL
Bit(2)) is taken care of in patch:
KVM/SVM/VMX/x86/spectre_v2: Support the combination of guest and host IBRS
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
[dwmw2: Handle 4.9 guest CPUID differences, rename
guest_cpu_has_ibrs() → guest_cpu_has_spec_ctrl()]
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/cpuid.c | 2 +-
arch/x86/kvm/cpuid.h | 4 ++--
arch/x86/kvm/svm.c | 4 ++--
arch/x86/kvm/vmx.c | 6 +++---
4 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index bcebe84..237e926 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -382,7 +382,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
/* cpuid 7.0.edx*/
const u32 kvm_cpuid_7_0_edx_x86_features =
- F(SPEC_CTRL) | F(ARCH_CAPABILITIES);
+ F(SPEC_CTRL) | F(RDS) | F(ARCH_CAPABILITIES);
/* all calls to cpuid_count() should be made on the same cpu */
get_cpu();
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 841e80d..39dd457 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -163,7 +163,7 @@ static inline bool guest_cpuid_has_ibpb(struct kvm_vcpu *vcpu)
return best && (best->edx & bit(X86_FEATURE_SPEC_CTRL));
}
-static inline bool guest_cpuid_has_ibrs(struct kvm_vcpu *vcpu)
+static inline bool guest_cpuid_has_spec_ctrl(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
@@ -171,7 +171,7 @@ static inline bool guest_cpuid_has_ibrs(struct kvm_vcpu *vcpu)
if (best && (best->ebx & bit(X86_FEATURE_IBRS)))
return true;
best = kvm_find_cpuid_entry(vcpu, 7, 0);
- return best && (best->edx & bit(X86_FEATURE_SPEC_CTRL));
+ return best && (best->edx & (bit(X86_FEATURE_SPEC_CTRL) | bit(X86_FEATURE_RDS)));
}
static inline bool guest_cpuid_has_arch_capabilities(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a07579f..43736dd 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3540,7 +3540,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
break;
case MSR_IA32_SPEC_CTRL:
if (!msr_info->host_initiated &&
- !guest_cpuid_has_ibrs(vcpu))
+ !guest_cpuid_has_spec_ctrl(vcpu))
return 1;
msr_info->data = svm->spec_ctrl;
@@ -3631,7 +3631,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
break;
case MSR_IA32_SPEC_CTRL:
if (!msr->host_initiated &&
- !guest_cpuid_has_ibrs(vcpu))
+ !guest_cpuid_has_spec_ctrl(vcpu))
return 1;
/* The STIBP bit doesn't fault even if it's not advertised */
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c386d13..3210add 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3017,7 +3017,7 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
break;
case MSR_IA32_SPEC_CTRL:
if (!msr_info->host_initiated &&
- !guest_cpuid_has_ibrs(vcpu))
+ !guest_cpuid_has_spec_ctrl(vcpu))
return 1;
msr_info->data = to_vmx(vcpu)->spec_ctrl;
@@ -3129,11 +3129,11 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
break;
case MSR_IA32_SPEC_CTRL:
if (!msr_info->host_initiated &&
- !guest_cpuid_has_ibrs(vcpu))
+ !guest_cpuid_has_spec_ctrl(vcpu))
return 1;
/* The STIBP bit doesn't fault even if it's not advertised */
- if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP))
+ if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_RDS))
return 1;
vmx->spec_ctrl = data;
--
2.7.4
|
