passt/virtio.h, branch 2026_05_07.1afd4ed

vhost_user: Fix assorted minor cppcheck warnings

2026-03-28T13:35:39+00:00

This fixes a batch of minor incorrect format specifier and "could be const"
warnings in the vhost_user code.  For some very strange reason, cppcheck
doesn't catch these errors right now, but does after code rearrangements
we're making for the dynamic forwarding update stuff.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

virtio: Pass iovec arrays as separate parameters to vu_queue_pop()

2026-03-20T19:05:12+00:00

Currently vu_queue_pop() and vu_queue_map_desc() read the iovec arrays
(in_sg/out_sg) and their sizes (in_num/out_num) from the vu_virtq_element
struct.  This couples the iovec storage to the element, requiring callers
like vu_handle_tx() to pre-initialize the element fields before calling
vu_queue_pop().

Pass the iovec arrays and their maximum sizes as separate parameters
instead.  vu_queue_map_desc() now writes the actual descriptor count
and iovec pointers back into the element after mapping, rather than
using the element as both input and output.

This decouples the iovec storage from the element, which is a
prerequisite for multi-buffer support where a single frame can span
multiple virtqueue elements sharing a common iovec pool.

No functional change.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

virtio: Introduce VNET_HLEN macro for virtio net header length

2026-02-15T01:52:51+00:00

Replace all open-coded sizeof(struct virtio_net_hdr_mrg_rxbuf) with a
VNET_HLEN macro.

Signed-off-by: Laurent Vivier 
Signed-off-by: Stefano Brivio

vhost-user: Fix VHOST_USER_GET_QUEUE_NUM to return number of queues

2025-09-09T19:13:59+00:00

The vhost-user specification states that VHOST_USER_GET_QUEUE_NUM should
return the maximum number of queues supported by the back-end, not the
number of virtqueues. Since each queue pair consists of RX and TX
virtqueues, we need to divide VHOST_USER_MAX_QUEUES by 2 to get the
correct queue count.

Also rename VHOST_USER_MAX_QUEUES to VHOST_USER_MAX_VQS throughout the
codebase to better reflect that it represents the maximum number of
virtqueues, not queue pairs.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

packet: Refactor vhost-user memory region handling

2025-09-03T18:43:48+00:00

This patch refactors the handling of vhost-user memory regions by
introducing a new `struct vdev_memory` to encapsulate the regions
array and their count (`nregions`) within the main `vu_dev` structure.

This new `vdev_memory` structure is then passed to the packet pool by
re-using the existing `p->buf` field. A `p->buf_size` of 0 indicates
that `p->buf` holds a pointer to `struct vdev_memory` instead of a
regular packet buffer. A new helper, `get_vdev_memory()`, is added to
abstract this access pattern.

Previous implementation was using a marker at the end of the memory
regions array. We can now uses all the slots.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

style: Fix 'Return' comment style

2025-07-18T17:19:24+00:00

We always use imperative (no 'Returns:'), no tab after the ':' and
only one space, the first character is always lowercase.

This is fixed with:

 sed -i "s/Returns:/Return:/;s/Return:    /Return: /;s/Return:  */Return: /;s/Return: \([A-Z]\)/Return: \L\1/" *.[ch]

And manually updated to fix alignment of multiline comment and words
that must keep uppercase (like IPv4, TCP, UDP, Layer-4).

Signed-off-by: Laurent Vivier 
Signed-off-by: Stefano Brivio

virtio: Correct and align comment headers

2025-05-16T16:27:11+00:00

Standardize and fix issues in `virtio.c` and `virtio.h` comment headers.

Improvements include:
- Added `()` to function names in comment summaries.
- Added colons after parameter and enum member tags.
- Changed `/*` to `/**` for `virtq_avail_event()` comment.
- Fixed typos (e.g., "file"->"fill", "virqueue"->"virtqueue").
- Added missing `Return:` tag for `vu_queue_rewind()`.
- Corrected parameter names in `virtio.h` comments to match code.

Signed-off-by: Laurent Vivier 
Signed-off-by: Stefano Brivio

vhost_user: Don't export several functions

2025-03-07T01:21:24+00:00

vhost-user added several functions which are exposed in headers, but not
used outside the file where they're defined.  I can't tell if these are
really internal functions, or of they're logically supposed to be exported,
but we don't happen to have anything using them yet.

For the time being, just remove the exports.  We can add them back if we
need to.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

migrate: Skeleton of live migration logic

2025-02-12T18:47:07+00:00

Introduce facilities for guest migration on top of vhost-user
infrastructure.  Add migration facilities based on top of the current
vhost-user infrastructure, moving vu_migrate() and related functions
to migrate.c.

Versioned migration stages define function pointers to be called on
source or target, or data sections that need to be transferred.

The migration header consists of a magic number, a version number for the
encoding, and a "compat_version" which represents the oldest version which
is compatible with the current one.  We don't use it yet, but that allows
for the future possibility of backwards compatible protocol extensions.

Co-authored-by: David Gibson 
Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

vhost-user: add VHOST_USER_SET_DEVICE_STATE_FD command

2025-01-20T18:51:24+00:00

Set the file descriptor to use to transfer the
backend device state during migration.

Signed-off-by: Laurent Vivier 
[sbrivio: Fixed nits and coding style here and there]
Signed-off-by: Stefano Brivio