Re: [PATCH 09/19] kvm: x86: Prepare reallocation check

Paolo Bonzini
2021-12-14T10:16:23Z

On 12/14/21 08:06, Tian, Kevin wrote:
>> - if (dynamic_enabled & ~guest_fpu->user_perm) != 0, then this is a
>> userspace error and you can #GP the guest without any issue. Userspace
>> is buggy
>
> Is it a general guideline that an error caused by emulation itself (e.g.
> due to no memory) can be reflected into the guest as #GP, even
> when from guest p.o.v there is nothing wrong with its setting?

No memory is a tricky one, if possible it should propagate -ENOMEM up to
KVM_RUN or KVM_SET_MSR. But it's basically an impossible case anyway,
because even with 8K TILEDATA we're within the limit of
PAGE_ALLOC_COSTLY_ORDER.

So, since it's not easy to do it right now, we can look at it later.

Paolo