Re: [PATCH 01/61] KVM: x86: Return -E2BIG when KVM_GET_SUPPORTED_CPUID hits max entries

[Paolo Bonzini]

On 03/02/20 16:59, Sean Christopherson wrote:
> 
>> In particular, here the change is both the
>> return value and the fact that we don't do copy_to_user() anymore so I
>> think it's possible to meet a userspace which is going to get broken by
>> the change.
> Ugh, yeah, it would be possible.  Qemu (retries), CrosVM (hardcoded to
> 256 entries) and Firecracker (doesn't use the ioctl()) are all ok,
> hopefully all other VMMs used in production environments follow suit.
> 

Also: lkvm and selftests both hardcode the limit to 100.

Both would be broken by this change, but as long as the limit is < 100
now it is fine to change.

Paolo