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KVM: x86: Do kvm_cpuid_array capacity checks in terminal functions

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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@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2020-03-02 15:56:56 -08:00 committed by Paolo Bonzini
parent dd69cc2542
commit 7c7f954810
1 changed files with 6 additions and 5 deletions
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11
arch/x86/kvm/cpuid.c
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@ -473,8 +473,12 @@ 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;
@ -511,7 +515,7 @@ 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) {
@ -782,9 +786,6 @@ out:
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);