Re: [PATCH RFC v3 2/6] rust/helpers: add virtio.c

[Manos Pitsidianakis <manos@pitsidianak.is>]

On Thu, 21 May 2026 12:03, Eugenio Perez Martin <eperezma@redhat.com> wrote:
>On Sun, May 10, 2026 at 3:38 PM Manos Pitsidianakis
><manos@pitsidianak.is> wrote:
>>
>> Some internal kernel virtio API functions are inline macros, so define
>> their symbols in a helper file.
>>
>> Signed-off-by: Manos Pitsidianakis <manos@pitsidianak.is>
>> ---
>>  MAINTAINERS            |  6 ++++++
>>  rust/helpers/helpers.c |  1 +
>>  rust/helpers/virtio.c  | 37 +++++++++++++++++++++++++++++++++++++
>>  3 files changed, 44 insertions(+)
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index d1cc0e12fe1f004da89b1aa339116908f642e894..48c9c666d90b5a256ab6fae1f42508b789a0ce50 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -27930,6 +27930,12 @@ F:     include/uapi/linux/virtio_*.h
>>  F:     net/vmw_vsock/virtio*
>>  F:     tools/virtio/
>>
>> +VIRTIO CORE API BINDINGS [RUST]
>> +M:     Manos Pitsidianakis <manos@pitsidianak.is>
>> +L:     virtualization@lists.linux.dev
>> +S:     Maintained
>> +F:     rust/helpers/virtio.c
>> +
>>  VIRTIO CRYPTO DRIVER
>>  M:     Gonglei <arei.gonglei@huawei.com>
>>  L:     virtualization@lists.linux.dev
>> diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
>> index a3c42e51f00a0990bea81ebce6e99bb397ce7533..5dc0d2f2ee6bd2ae8e6abfe4baa247c1963967f6 100644
>> --- a/rust/helpers/helpers.c
>> +++ b/rust/helpers/helpers.c
>> @@ -61,6 +61,7 @@
>>  #include "time.c"
>>  #include "uaccess.c"
>>  #include "usb.c"
>> +#include "virtio.c"
>>  #include "vmalloc.c"
>>  #include "wait.c"
>>  #include "workqueue.c"
>> diff --git a/rust/helpers/virtio.c b/rust/helpers/virtio.c
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..46aeeb063158823e66477777b3cd4bd1525df330
>> --- /dev/null
>> +++ b/rust/helpers/virtio.c
>> @@ -0,0 +1,37 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +#ifdef CONFIG_VIRTIO
>> +#include <linux/virtio_config.h>
>> +
>> +__rust_helper bool
>> +rust_helper_virtio_has_feature(const struct virtio_device *vdev,
>> +                              unsigned int fbit)
>> +{
>> +       return virtio_has_feature(vdev, fbit);
>> +}
>> +__rust_helper void rust_helper_virtio_get_features(struct virtio_device *vdev,
>> +                                                  u64 *features_out)
>> +{
>> +       return virtio_get_features(vdev, features_out);
>
>As a suggestion, perhaps an API that allows getting feature bits > 64,
>like VIRTIO_NET_F_GUEST_UDP_TUNNEL_GSO (65) or VIRTIO_NET_F_IPSEC (70)
>could save the need to add more functions in the future.

Yes, this will be needed indeed. I think however that as long as no 
driver that uses features exists, this would be dead code so we should 
not include it until it's needed.

I plan on dropping these helper bindings that have no user in my patches 
in the next revisions.

>
>> +}
>> +
>> +__rust_helper int rust_helper_virtio_find_vqs(struct virtio_device *vdev,
>> +                                             unsigned int nvqs,
>> +                                             struct virtqueue *vqs[],
>> +                                             struct virtqueue_info vqs_info[],
>> +                                             struct irq_affinity *desc)
>> +{
>> +       return virtio_find_vqs(vdev, nvqs, vqs, vqs_info, desc);
>> +}
>> +
>> +__rust_helper void rust_helper_virtio_device_ready(struct virtio_device *dev)
>> +{
>> +       return virtio_device_ready(dev);
>> +}
>> +
>> +__rust_helper bool
>> +rust_helper_virtio_is_little_endian(struct virtio_device *vdev)
>> +{
>> +       return virtio_is_little_endian(vdev);
>> +}
>> +#endif /* CONFIG_VIRTIO */
>>
>> --
>> 2.47.3
>>
>