Re: [PATCH 2/2] KVM: x86: Use memcmp in kvm_cpuid_check_equal()

[Vitaly Kuznetsov]

Joe Perches <joe@xxxxxxxxxxx> writes:

> On Mon, 2022-01-24 at 11:36 +0100, Vitaly Kuznetsov wrote:
>> kvm_cpuid_check_equal() should also check .flags equality but instead
>> of adding it to the existing check, just switch to using memcmp() for
>> the whole 'struct kvm_cpuid_entry2'.
>
> Is the struct padding guaranteed to be identical ?
>

Well, yes (or we're all doomeed):
- 'struct kvm_cpuid_entry2' is part of KVM userspace ABI, it is supposed
to be stable.
- Here we compare structs which come from the same userspace during one
session (vCPU fd stays open), I can't imagine how structure layout can
change on-the-fly.

-- 
Vitaly