From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v2 2/3] KVM: VMX: validate individual bits of guest MSR_IA32_FEATURE_CONTROL Date: Thu, 16 Jun 2016 12:01:13 +0200 Message-ID: <088f9fcb-a648-05d4-530a-790cb084bd09@redhat.com> References: <20160616060531.30028-1-haozhong.zhang@intel.com> <20160616060531.30028-3-haozhong.zhang@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: rkrcmar@redhat.com, Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Gleb Natapov , Boris Petkov , Tony Luck , Andi Kleen , Ashok Raj To: Haozhong Zhang , kvm@vger.kernel.org Return-path: In-Reply-To: <20160616060531.30028-3-haozhong.zhang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 16/06/2016 08:05, Haozhong Zhang wrote: > +/* > + * FEATURE_CONTROL_LOCKED is added/removed automatically by > + * feature_control_valid_bits_add/del(), so it's not included here. > + */ > +#define FEATURE_CONTROL_MAX_VALID_BITS \ > + FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX > + > +static void feature_control_valid_bits_add(struct kvm_vcpu *vcpu, uint64_t bits) > +{ > + ASSERT(!(bits & ~FEATURE_CONTROL_MAX_VALID_BITS)); The KVM-specific ASSERT macro should go. You can use WARN_ON. However, I think FEATURE_CONTROL_LOCKED should always be writable. If you change that, it's simpler to just do |= and &= in the caller. > + to_vmx(vcpu)->msr_ia32_feature_control_valid_bits |= > + bits | FEATURE_CONTROL_LOCKED; > +} > + > +static void feature_control_valid_bits_del(struct kvm_vcpu *vcpu, uint64_t bits) > +{ > + uint64_t *valid_bits = > + &to_vmx(vcpu)->msr_ia32_feature_control_valid_bits; > + ASSERT(!(bits & ~FEATURE_CONTROL_MAX_VALID_BITS)); > + *valid_bits &= ~bits; > + if (!(*valid_bits & ~FEATURE_CONTROL_LOCKED)) > + *valid_bits = 0; > +} > + > #define VMCS12_OFFSET(x) offsetof(struct vmcs12, x) > #define FIELD(number, name) [number] = VMCS12_OFFSET(name) > #define FIELD64(number, name) [number] = VMCS12_OFFSET(name), \ > @@ -2864,6 +2897,14 @@ 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 valid_bits && !(val & ~valid_bits); > +} > /* > * Reads an msr value (of 'msr_index') into 'pdata'. > * Returns 0 on success, non-0 otherwise. > @@ -2906,7 +2947,7 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > msr_info->data = vmcs_read64(GUEST_BNDCFGS); > break; > case MSR_IA32_FEATURE_CONTROL: > - if (!nested_vmx_allowed(vcpu)) > + if (!vmx_feature_control_msr_valid(vcpu, 0)) You can remove this if completely in patch 1. It's okay to make the MSR always available. Thanks, Paolo > return 1; > msr_info->data = to_vmx(vcpu)->msr_ia32_feature_control; > break; > @@ -2999,7 +3040,7 @@ 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; > @@ -9095,6 +9136,13 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu) > vmx->nested.nested_vmx_secondary_ctls_high &= > ~SECONDARY_EXEC_PCOMMIT; > } > + > + if (nested_vmx_allowed(vcpu)) > + feature_control_valid_bits_add > + (vcpu, FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX); > + else > + feature_control_valid_bits_del > + (vcpu, FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX); > }