linux-toradex.git/include/linux/virtio_config.h, branch v6.18-rc2

virtio: introduce map ops in virtio core

2025-10-01T11:24:43+00:00

This patch introduces map operations for virtio device. Virtio used to
use DMA API which is not necessarily the case since some devices
doesn't do DMA. Instead of using tricks and abusing DMA API, let's
simply abstract the current mapping logic into a virtio specific
mapping operations. For the device or transport that doesn't do DMA,
they can implement their own mapping logic without the need to trick
DMA core. In this case the mapping metadata is opaque to the virtio
core that will be passed back to the transport or device specific map
operations. For other devices, DMA API will still be used, so map
token will still be the dma device to minimize the changeset and
performance impact.

The mapping operations are abstracted as a independent structure
instead of reusing virtio_config_ops. This allows the transport can
simply reuse the structure for lower layers like vDPA.

A set of new mapping helpers were introduced for the device that want
to do mapping by themselves.

Signed-off-by: Jason Wang 
Message-Id: <20250821064641.5025-7-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin 
Tested-by: Lei Yang 
Reviewed-by: Eugenio Pérez

virtio_config: clarify output parameters

2025-09-21T21:44:20+00:00

This was ambiguous enough for a broken patch (206cc44588f7 ("virtio:
reject shm region if length is zero")) to make it into the kernel, so
make it clearer.

Link: https://lore.kernel.org/r/20250816071600-mutt-send-email-mst@kernel.org/
Signed-off-by: Alyssa Ross 
Message-Id: <20250829150944.233505-1-hi@alyssa.is>
Signed-off-by: Michael S. Tsirkin

Revert "virtio: reject shm region if length is zero"

2025-08-26T07:38:10+00:00

The commit 206cc44588f7 ("virtio: reject shm region if length is zero")
breaks the Virtio-gpu `host_visible` feature.

As you can see in the snippet below, host_visible_region is zero because
of the `kzalloc`.  It's using the `vm_get_shm_region`
(drivers/virtio/virtio_mmio.c:536) to read the `addr` and `len` from
qemu/crosvm.

```
drivers/gpu/drm/virtio/virtgpu_kms.c
132         vgdev = drmm_kzalloc(dev, sizeof(struct virtio_gpu_device), GFP_KERNEL);
[...]
177         if (virtio_get_shm_region(vgdev->vdev, &vgdev->host_visible_region,
178                                   VIRTIO_GPU_SHM_ID_HOST_VISIBLE)) {
```
Now it always fails.

To fix, revert the offending commit.

Fixes: 206cc44588f7 ("virtio: reject shm region if length is zero")
Signed-off-by: Igor Torrente 
Message-Id: <20250807124145.81816-1-igor.torrente@collabora.com>
Signed-off-by: Michael S. Tsirkin

virtio: introduce extended features

2025-07-08T16:04:58+00:00

The virtio specifications allows for up to 128 bits for the
device features. Soon we are going to use some of the 'extended'
bits features (above 64) for the virtio_net driver.

Introduce extended features as a fixed size array of u64. To minimize
the diffstat allows legacy driver to access the low 64 bits via a
transparent union.

Introduce an extended get_extended_features configuration callback
that devices supporting the extended features range must implement in
place of the traditional one.

Note that legacy and transport features don't need any change, as
they are always in the low 64 bit range.

Acked-by: Jason Wang 
Signed-off-by: Paolo Abeni

virtio: reject shm region if length is zero

2025-05-28T07:19:03+00:00

Prevent usage of shared memory regions where the length is zero,
as such configurations are not valid and may lead to unexpected behavior.

Signed-off-by: Sami Uddin 
Message-Id: <20250511222153.2332-1-sami.md.ko@gmail.com>
Signed-off-by: Michael S. Tsirkin

virtio: create admin queues alongside other virtqueues

2024-07-17T09:43:21+00:00

Admin virtqueue is just another virtqueue nothing that special about it.
The current implementation treats it somehow separate though in terms
of creation and deletion. Unify the admin virtqueue creation and
deletion flows to be aligned with the rest of virtqueues, creating
it from vp_find_vqs_*() helpers. Let the admin virtqueue to be deleted
by vp_del_vqs() as the rest.

Call vp_find_one_vq_msix() with slow_path argument being "true" to make
sure that in case of limited interrupt vectors the config vector is used
for admin queue.

Signed-off-by: Jiri Pirko 
Message-Id: <20240716113552.80599-10-jiri@resnulli.us>
Signed-off-by: Michael S. Tsirkin

virtio: rename virtio_find_vqs_info() to virtio_find_vqs()

2024-07-17T09:20:58+00:00

Since the original virtio_find_vqs() is no longer present, rename
virtio_find_vqs_info() back to virtio_find_vqs().

Signed-off-by: Jiri Pirko 
Message-Id: <20240708074814.1739223-20-jiri@resnulli.us>
Signed-off-by: Michael S. Tsirkin

virtio: remove unused virtio_find_vqs() and virtio_find_vqs_ctx() helpers

2024-07-17T09:20:58+00:00

All callers of virtio_find_vqs() and virtio_find_vqs_ctx() were
converted to use virtio_find_vqs_info(). Remove no longer used helpers.

Signed-off-by: Jiri Pirko 
Message-Id: <20240708074814.1739223-19-jiri@resnulli.us>
Signed-off-by: Michael S. Tsirkin

virtio: rename find_vqs_info() op to find_vqs()

2024-07-17T09:20:57+00:00

Since the original find_vqs() is no longer present, rename
find_vqs_info() back to find_vqs().

Signed-off-by: Jiri Pirko 
Message-Id: <20240708074814.1739223-10-jiri@resnulli.us>
Signed-off-by: Michael S. Tsirkin

virtio: remove the original find_vqs() op

2024-07-17T09:20:57+00:00

As it is no longer used, remove it.

Signed-off-by: Jiri Pirko 
Message-Id: <20240708074814.1739223-9-jiri@resnulli.us>
Signed-off-by: Michael S. Tsirkin