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

[Greg KH]

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 :(