RE: [PATCH v3 1/1] Documentation: hyperv: Update documentation for sending VMBus packets

[Michael Kelley]

From: Naman Jain <namjain@xxxxxxxxxxxxxxxxxxx> Sent: Tuesday, October 13, 2026 1:42 AM
> 
> On 10/13/2026 7:13 AM, Michael Kelley wrote:
> > The functions for sending VMBus packets have changed.
> > vmbus_sendpacket_mpb_desc() can target multiple ranges, and
> > vmbus_sendpacket_pagebuffer() has been removed. vmbus_sendpacket_getid()
> > has been added. Update the documentation accordingly.
> >
> > Fixes: 45a442fe369e ("Drivers: hv: vmbus: Remove vmbus_sendpacket_pagebuffer()")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
> > ---
> > Changes in v3:
> > * Fixed typo in the documentation text [Sashiko]
> >
> > Changes in v2:
> > * Add vmbus_sendpacket_getid() to the documentation. [Naman Jain]
> >
> >   Documentation/virt/hyperv/vmbus.rst | 17 +++++++++--------
> >   1 file changed, 9 insertions(+), 8 deletions(-)
> >
> > diff --git a/Documentation/virt/hyperv/vmbus.rst b/Documentation/virt/hyperv/vmbus.rst
> > index 654bb4849972..c546e821ce6b 100644
> > --- a/Documentation/virt/hyperv/vmbus.rst
> > +++ b/Documentation/virt/hyperv/vmbus.rst
> > @@ -141,14 +141,15 @@ Three functions exist to send VMBus channel messages:
> >
> >   1. vmbus_sendpacket():  Control-only messages and messages with
> >      embedded data -- no GPAs
> > -2. vmbus_sendpacket_pagebuffer(): Message with list of GPAs
> > -   identifying data to transfer.  An offset and length is
> > -   associated with each GPA so that multiple discontinuous areas
> > -   of guest memory can be targeted.
> > -3. vmbus_sendpacket_mpb_desc(): Message with list of GPAs
> > -   identifying data to transfer.  A single offset and length is
> > -   associated with a list of GPAs.  The GPAs must describe a
> > -   single logical area of guest memory to be targeted.
> > +2. vmbus_sendpacket_getid(): Similar to vmbus_sendpacket() but returns
> > +   a transaction ID that is matched against a reply from the Hyper-V
> > +   host. Useful when the struct completion (or other rendezvous data)
> > +   must reside on the caller's stack. By invalidating the transaction
> > +   ID before exiting the function due to a timeout or other error, a
> > +   late arriving interrupt is assured to not trash the stack.
> > +3. vmbus_sendpacket_mpb_desc(): Message with one or more data ranges
> > +   to target. Each range consists of a single offset and length plus
> > +   a list of GPAs that describe a logical area of guest memory.
> >
> >   Historically, Linux guests have trusted Hyper-V to send well-formed
> >   and valid messages, and Linux drivers for synthetic devices did not
> 
> We can retain the review tags for minor edits.
> 
> Reviewed-by: Naman Jain <namjain@xxxxxxxxxxxxxxxxxxx>

I just forgot to carry your previous R-b tag forward. :-(  Thanks for
doing it again.

Michael