Re: ioregionfd with io_uring IORING_OP_URING_CMD

[Stefan Hajnoczi]

On Tue, 7 Jun 2022 at 14:32, Elena <elena.ufimtseva@oracle.com> wrote:
> On Mon, Jun 06, 2022 at 03:57:47PM +0100, Stefan Hajnoczi wrote:
> > The downside is it requires more code than general purpose I/O. In
> > addition to ->uring_cmd(), it's also worth implementing struct
> > file_operations read/write/poll so traditional file I/O syscalls work
> > for simple applications that don't want to use io_uring.
> >
> > It's possible to add ->uring_cmd() later but as a userspace developer I
> > would prefer the ->uring_cmd() approach, so I'm not sure it's worth
> > committing to the existing userspace-provided file approach?
>
> Makes total sense. I am going to start working on this and will
> come back with more questions.

Good to hear!

Userspace needs a way to create these fds. I think a new
ioctl(KVM_CREATE_IOREGIONFD) is needed. Then the fd can be passed back
to KVM_SET_IOREGION.

Stefan