Re: [PATCH v3 04/34] KVM: x86: hyper-v: Handle HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX} calls gently

Sean Christopherson
2022-05-18T14:18:48Z

On Wed, May 18, 2022, Vitaly Kuznetsov wrote:
> Maxim Levitsky <mlevitsk@redhat.com> writes:
> > Or if using kfifo, then it can contain plain u64 items, which is even more natural.
> >
>
> In the next version I switch to fifo and get rid of 'flush_all' entries
> but instead of a boolean I use a 'magic' value of '-1' in GVA. This way
> we don't need to synchronize with the reader and add any special
> handling for the flag.

Isn't -1 theoretically possible? Or is wrapping not allowed? E.g. requesting a
flush for address=0xfffffffffffff000, count = 0xfff will yield -1 and doesn't
create any illegal addresses in the process.