Fix read/write to IA32_FEATURE_CONTROL MSR in nested environment.
This patch simulate this MSR in nested_vmx and the default value is
0x0. BIOS should set it to 0x5 before VMXON. After setting the lock
bit, write to it will cause #GP(0).
Signed-off-by: Arthur Chunqi Li <yzt...@gmail.com>
---
arch/x86/kvm/vmx.c | 25 +++++++++++++++++++++----
arch/x86/kvm/x86.c | 3 ++-
2 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 260a919..5e3d44e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -373,6 +373,7 @@ struct nested_vmx {
* we must keep them pinned while L2 runs.
*/
struct page *apic_access_page;
+ u64 msr_ia32_feature_control;
};
#define POSTED_INTR_ON 0
@@ -2277,8 +2278,11 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32
msr_index, u64 *pdata)
switch (msr_index) {
case MSR_IA32_FEATURE_CONTROL:
- *pdata = 0;
- break;
+ if (nested_vmx_allowed(vcpu)){
+ *pdata = to_vmx(vcpu)->nested.msr_ia32_feature_control;
+ break;
+ }
+ return 0;
case MSR_IA32_VMX_BASIC:
/*
* This MSR reports some information about VMX support. We
@@ -2356,9 +2360,13 @@ static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32
msr_index, u64 data)
if (!nested_vmx_allowed(vcpu))
return 0;
- if (msr_index == MSR_IA32_FEATURE_CONTROL)
- /* TODO: the right thing. */
+ if (msr_index == MSR_IA32_FEATURE_CONTROL){
+ if (to_vmx(vcpu)->nested.msr_ia32_feature_control
+ & FEATURE_CONTROL_LOCKED)
+ return 0;
+ to_vmx(vcpu)->nested.msr_ia32_feature_control = data;
return 1;
+ }
/*
* No need to treat VMX capability MSRs specially: If we don't handle
* them, handle_wrmsr will #GP(0), which is correct (they are readonly)
@@ -5595,6 +5603,15 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
skip_emulated_instruction(vcpu);
return 1;
}
+
+#define VMXON_NEEDED_FEATURES \
+ (FEATURE_CONTROL_LOCKED | FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX)
+ if ((vmx->nested.msr_ia32_feature_control & VMXON_NEEDED_FEATURES)
+ != VMXON_NEEDED_FEATURES) {
+ kvm_inject_gp(vcpu, 0);
+ return 1;
+ }
+
if (enable_shadow_vmcs) {
shadow_vmcs = alloc_vmcs();
if (!shadow_vmcs)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e8ba99c..2d4eb8e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -850,7 +850,8 @@ static u32 msrs_to_save[] = {
#ifdef CONFIG_X86_64
MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
#endif
- MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA
+ MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
+ MSR_IA32_FEATURE_CONTROL
};
static unsigned num_msrs_to_save;
--
1.7.9.5
--
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