Re: [PATCH] misc: vmw_zerocopy: Add VMware zero-copy buffer sharing driver

[Greg KH]

On Sat, Jun 20, 2026 at 07:04:55AM +0200, Greg KH wrote:
> On Fri, Jun 19, 2026 at 11:27:10AM -0700, Rishi Chhibber wrote:
> > This driver implements a misc character device (/dev/vmw_zc) that allows
> > guest userspace applications to share pinned memory buffers with a
> > VMware hypervisor-side peer using the VMCI datagram interface.
> > 
> > The driver pins user pages via get_user_pages_fast(), transmits their
> > physical page frame numbers to the hypervisor peer over VMCI, and avoids
> > an intermediate copy between the guest workload VM and the hypervisor.
> > 
> > The hypervisor-side peer for this interface only speaks VMCI; there is no
> > virtio backend implemented on the VMware host for it. The closest
> > existing upstream transport, vsock (virtio-vsock), provides a socket
> > bytestream/datagram abstraction and does not expose a way to hand a set
> > of pinned guest page frame numbers to the host for true zero-copy
> > access; it would still require copying the payload through the socket.
> > This driver's purpose is specifically to pin guest pages and pass their
> > PFNs to the host so the payload is never copied. It also supports
> > bundling multiple buffers in a single request, which is required for the
> > all-or-none semantics of page-level zero-copy transfers.
> > 
> > Signed-off-by: Rishi Chhibber <rishi.chhibber@xxxxxxxxxxxx>
> > ---
> > Changes in v3:
> 
> There is no "v3" in the subject line :(

And, because of this, I will strongly recommend and almost require now,
for you to get another internal person that has experience doing kernel
development, to review and sign off on the next version of your patch.

The community shouldn't be forced to do basic review like this, that's
what your coworkers are for.

thanks,

greg k-h