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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id 25sm98565wmg.30.2020.03.03.08.03.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Mar 2020 08:03:51 -0800 (PST) From: Vitaly Kuznetsov To: Sean Christopherson Cc: Paolo Bonzini , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li Subject: Re: [PATCH v2 53/66] KVM: x86: Do kvm_cpuid_array capacity checks in terminal functions In-Reply-To: <20200302235709.27467-54-sean.j.christopherson@intel.com> References: <20200302235709.27467-1-sean.j.christopherson@intel.com> <20200302235709.27467-54-sean.j.christopherson@intel.com> Date: Tue, 03 Mar 2020 17:03:50 +0100 Message-ID: <87d09tfms9.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sean Christopherson writes: > Perform the capacity checks on the userspace provided kvm_cpuid_array > in the lower __do_cpuid_func() and __do_cpuid_func_emulated(). > Pre-checking the array in do_cpuid_func() no longer adds value now that > __do_cpuid_func() has been trimmed down to size, i.e. doesn't invoke a > big pile of retpolined functions before doing anything useful. > > Note, __do_cpuid_func() already checks the array capacity via > do_host_cpuid(), "moving" the check to __do_cpuid_func() simply means > removing a WARN_ON(). > > Suggested-by: Vitaly Kuznetsov > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/cpuid.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index eebd7f613f67..f879fcbd6fb2 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -478,8 +478,12 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array, > > static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func) > { > - struct kvm_cpuid_entry2 *entry = &array->entries[array->nent]; > + struct kvm_cpuid_entry2 *entry; > > + if (array->nent >= array->maxnent) > + return -E2BIG; > + > + entry = &array->entries[array->nent]; > entry->function = func; > entry->index = 0; > entry->flags = 0; > @@ -516,7 +520,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) > r = -E2BIG; > > entry = do_host_cpuid(array, function, 0); > - if (WARN_ON(!entry)) > + if (!entry) > goto out; > > switch (function) { > @@ -787,9 +791,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) > static int do_cpuid_func(struct kvm_cpuid_array *array, u32 func, > unsigned int type) > { > - if (array->nent >= array->maxnent) > - return -E2BIG; > - > if (type == KVM_GET_EMULATED_CPUID) > return __do_cpuid_func_emulated(array, func); Reviewed-by: Vitaly Kuznetsov -- Vitaly