KVM: VMX: validate individual bits of guest MSR_IA32_FEATURE_CONTROL
KVM currently does not check the value written to guest
MSR_IA32_FEATURE_CONTROL, though bits corresponding to disabled features
may be set. This patch makes KVM to validate individual bits written to
guest MSR_IA32_FEATURE_CONTROL according to enabled features.
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ad66978..0a3ccb0 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -612,7 +612,13 @@
u32 guest_pkru;
u32 host_pkru;
+ /*
+ * Only bits masked by msr_ia32_feature_control_valid_bits can be set in
+ * msr_ia32_feature_control. FEATURE_CONTROL_LOCKED is always included
+ * in msr_ia32_feature_control_valid_bits.
+ */
u64 msr_ia32_feature_control;
+ u64 msr_ia32_feature_control_valid_bits;
};
enum segment_cache_field {
@@ -2929,6 +2935,14 @@
return 0;
}
+static inline bool vmx_feature_control_msr_valid(struct kvm_vcpu *vcpu,
+ uint64_t val)
+{
+ uint64_t valid_bits = to_vmx(vcpu)->msr_ia32_feature_control_valid_bits;
+
+ return !(val & ~valid_bits);
+}
+
/*
* Reads an msr value (of 'msr_index') into 'pdata'.
* Returns 0 on success, non-0 otherwise.
@@ -3062,7 +3076,7 @@
ret = kvm_set_msr_common(vcpu, msr_info);
break;
case MSR_IA32_FEATURE_CONTROL:
- if (!nested_vmx_allowed(vcpu) ||
+ if (!vmx_feature_control_msr_valid(vcpu, data) ||
(to_vmx(vcpu)->msr_ia32_feature_control &
FEATURE_CONTROL_LOCKED && !msr_info->host_initiated))
return 1;
@@ -9055,6 +9069,8 @@
goto free_vmcs;
}
+ vmx->msr_ia32_feature_control_valid_bits = FEATURE_CONTROL_LOCKED;
+
return &vmx->vcpu;
free_vmcs:
@@ -9202,6 +9218,13 @@
vmx->nested.nested_vmx_secondary_ctls_high &=
~SECONDARY_EXEC_PCOMMIT;
}
+
+ if (nested_vmx_allowed(vcpu))
+ to_vmx(vcpu)->msr_ia32_feature_control_valid_bits |=
+ FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
+ else
+ to_vmx(vcpu)->msr_ia32_feature_control_valid_bits &=
+ ~FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
}
static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)