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Date: Mon, 2 Mar 2020 15:56:56 -0800 From: Sean Christopherson <sean.j.christopherson@...el.com> To: Paolo Bonzini <pbonzini@...hat.com> Cc: Sean Christopherson <sean.j.christopherson@...el.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Wanpeng Li <wanpengli@...cent.com>, Jim Mattson <jmattson@...gle.com>, Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com> Subject: [PATCH v2 53/66] KVM: x86: Do kvm_cpuid_array capacity checks in terminal functions 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 <vkuznets@...hat.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com> --- 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); -- 2.24.1
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