From 37e4c997dadf713d5b9cb88a801eb38d61a2aefc Mon Sep 17 00:00:00 2001 From: Haozhong Zhang Date: Wed, 22 Jun 2016 14:59:55 +0800 Subject: [PATCH] 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 Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index ad66978281c1..0a3ccb073bb4 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -612,7 +612,13 @@ struct vcpu_vmx { 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 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata) 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 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 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 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) goto free_vmcs; } + vmx->msr_ia32_feature_control_valid_bits = FEATURE_CONTROL_LOCKED; + return &vmx->vcpu; free_vmcs: @@ -9202,6 +9218,13 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu) 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)