Re: [PATCH RFC v3 0/6] Add Rust virtio bindings and sample device

On Tue, Jul 21, 2026 at 8:24 AM Manos Pitsidianakis
<[email protected]> wrote:
>
> Ping.
>
> I have a different version of the series WIP with a virtio-rng instead
> of virtio-rtc, based on
> https://lore.kernel.org/lkml/20260529-rust-hw_random-virtio-rng-v1-0-b3153dd90311@pitsidianak.is/
> (which needs a v2 also)
>
> But since this series hasn't gotten any feedback on the virtio part, I'd
> like to ask if there is any before respinning.
>
> Thanks!
>

I also think this will be a great addition, but I have very little
knowledge of Rust. Is it easy to implement the simplest virtio-net
driver using Rust, without CVQ or extra features, so I can test it and
hopefully build features on top? Would it help?

Thanks!

> On Sun, 10 May 2026 16:38, Manos Pitsidianakis <[email protected]> wrote:
> >Hi all, this RFC series adds Rust bindings for Virtio drivers
> >(frontends in virtio parlance).
> >
> >As a PoC, it also adds a sample virtio-rtc driver which performs
> >capability discovery through the virtqueue without registering any clock.
> >
> >Before I send a cleaned-up non-RFC I would like some initial feedback
> >(i.e. is it something the upstream wants?)
> >
> >This was tested with the rust-vmm vhost-device-rtc device backend that I
> >wrote[^0]:
> >
> >[^0]: https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-rtc
> >
> >Instructions:
> >
> >  Run the daemon in a separate terminal:
> >
> >  $ cargo run --bin vhost-device-rtc -- -s /tmp/rtc.sock
> >
> >  Then run the VM:
> >
> >  $ qemu-system-aarch64 \
> >    -machine type=virt,virtualization=off,acpi=on \
> >    -cpu host \
> >    -smp 8 \
> >    -accel kvm \
> >    -drive if=virtio,format=qcow2,file=./debian-13-nocloud-arm64-daily.qcow2 \
> >    -device virtio-net-pci,netdev=unet \
> >    -device virtio-scsi-pci \
> >    -serial mon:stdio \
> >    -m 8192 \
> >    -object memory-backend-memfd,id=mem,size=8G,share=on \
> >    -numa node,memdev=mem \
> >    -display none \
> >    -vga none \
> >    -kernel /path/to/linux/build/arch/arm64/boot/Image \
> >    -device vhost-user-test-device,chardev=rtc,id=rtc,virtio-id=17,num_vqs=2,vq_size=1024 \
> >    -chardev socket,path=/tmp/rtc.sock,id=rtc \
> >    ...
> >
> >  Example output:
> >    [    1.105238] rust_virtio_rtc: Probe Rust virtio driver sample.
> >    [    1.105645] rust_virtio_rtc: Found 1 vqs.
> >    [    1.136050] rust_virtio_rtc: process_requestq got buf 16 bytes
> >    [    1.136125] rust_virtio_rtc: Got response! Ok(RespCfg { head: ReqHead { msg_type: Le16(0), reserved: [0, 0, 0, 0, 0, 0] }, num_clocks: Le16(3), reserved: [0, 0, 0, 0, 0, 0] })
> >    [    1.136701] rust_virtio_rtc: Got response! Ok(RespClockCap { head: ReqHead { msg_type: Le16(0), reserved: [0, 0, 0, 0, 0, 0] }, clock_type: 3, leap_second_smearing: 0, flags: 0, reserved: [0, 0, 0, 0, 0] })
> >    [    1.136724] rust_virtio_rtc virtio0: cannot expose clock 0 (type 3, variant 0, flags 0) to userspace
> >    [    1.137259] rust_virtio_rtc: Got response! Ok(RespRead { head: ReqHead { msg_type: Le16(0), reserved: [0, 0, 0, 0, 0, 0] }, clock_reading: Le64(1777890485031060388) })
> >    [    1.137277] rust_virtio_rtc: #0 clock reading = 1777890485031060388
> >    [    1.137749] rust_virtio_rtc: Got response! Ok(RespClockCap { head: ReqHead { msg_type: Le16(0), reserved: [0, 0, 0, 0, 0, 0] }, clock_type: 1, leap_second_smearing: 0, flags: 0, reserved: [0, 0, 0, 0, 0] })
> >    [    1.137769] rust_virtio_rtc virtio0: cannot expose clock 1 (type 1, variant 0, flags 0) to userspace
> >    [    1.138247] rust_virtio_rtc: Got response! Ok(RespRead { head: ReqHead { msg_type: Le16(0), reserved: [0, 0, 0, 0, 0, 0] }, clock_reading: Le64(1777890485032086075) })
> >    [    1.138264] rust_virtio_rtc: #1 clock reading = 1777890485032086075
> >    [    1.138730] rust_virtio_rtc: Got response! Ok(RespClockCap { head: ReqHead { msg_type: Le16(0), reserved: [0, 0, 0, 0, 0, 0] }, clock_type: 2, leap_second_smearing: 0, flags: 0, reserved: [0, 0, 0, 0, 0] })
> >    [    1.138751] rust_virtio_rtc virtio0: cannot expose clock 2 (type 2, variant 0, flags 0) to userspace
> >    [    1.139253] rust_virtio_rtc: Got response! Ok(RespRead { head: ReqHead { msg_type: Le16(0), reserved: [0, 0, 0, 0, 0, 0] }, clock_reading: Le64(338567896865557) })
> >    [    1.139270] rust_virtio_rtc: #2 clock reading = 338567896865557
> >
> >Concerns - Notes - TODOs
> >========================
> >
> >- Virtqueue lifetimes don't neatly apply to Rust as expected, so a lot
> >  of times we have to go through unsafe pointer dereferences (though
> >  which are guaranteed by Virtio subsystem to be valid, for example when
> >  a callback is called with the vq argument). There's a potential for
> >  misuse and definitely could use better thinking.
> >- `struct virtio_device` is not reference-counted like other implemented
> >  device types in rust/kernel. Maybe we need to change C API first to
> >  make them reference counted, assuming this doesn't break anything?
> >- The sample driver obviously conflicts with the C implementation, so
> >  this would either need to move out of samples/ or figure out some way
> >  to handle this in kbuild.
> >- kernel::virtio module and its types need a few rustdoc examples that I
> >  will add in followup series
> >- Note that the registration of RTC clocks etc in the sample driver is
> >  not done, I'm putting it off until I receive some feedback first. The
> >  sample driver otherwise does send and receive data from the virtqueue
> >  as a PoC.
> >
> >PS: No LLMs used so any mistakes and goofs are solely written by me.
> >
> >Signed-off-by: Manos Pitsidianakis <[email protected]>
> >---
> >Changes in v3:
> >- Removed unused methods from virtio API
> >- Clean up how scattergather lists are added to virtqueues by using
> >  owned SGTables only, and make the API safe(r)
> >- Add RAII cleanup for find_vqs return value that calls del_vqs
> >- Reset device after remove callback
> >- Significantly clean up sample driver as a result of the other cleanups
> >- Link to v2: https://lore.kernel.org/r/[email protected]
> >
> >Changes in v2:
> >- Move helper ifdefs to helper file (thanks Alice)
> >- Changed CONFIG checks to IS_ENABLED to allow for CONFIG_VIRTIO=m
> >- Split all use imports to one item per line according to style guide
> >- Fixed wait_for_completion_interruptible*() rustdocs
> >- Use Jiffy type alias in wait_for_completion_interruptible_timeout()
> >- Pepper and salt #[inline]s wherever appropriate as per style guide
> >- Split probe() into probe() and init() to allow cleaning up if init
> >  fails
> >- Remove unnecessary Send and Sync unsafe impls for
> >  kernel::virtio::Device
> >- Remove unnecessary LeSize and BeSize
> >- Accept Option<_> for virtqueue callback when creating a VirtqueueInfo
> >- Made all vq buffer adding operations unsafe
> >- Use AtomicU16 instead of Cell<u16> for sample virtio driver
> >- Fix RespHead field types in sample virtio driver
> >- Fix response error checking in sample virtio driver
> >- Change some device contexts in method signatures
> >- Link to v1: https://lore.kernel.org/r/[email protected]
> >
> >---
> >Manos Pitsidianakis (6):
> >      rust/bindings: generate virtio bindings
> >      rust/helpers: add virtio.c
> >      rust/kernel/device: return parent at same context
> >      rust: add virtio module
> >      rust: impl interruptible waits for Completion
> >      samples/rust: Add sample virtio-rtc driver [WIP]
> >
> > MAINTAINERS                     |   9 +
> > rust/bindings/bindings_helper.h |   5 +
> > rust/helpers/helpers.c          |   1 +
> > rust/helpers/virtio.c           |  37 ++++
> > rust/kernel/device.rs           |   2 +-
> > rust/kernel/lib.rs              |   2 +
> > rust/kernel/sync/completion.rs  |  42 +++-
> > rust/kernel/virtio.rs           | 423 ++++++++++++++++++++++++++++++++++++++++
> > rust/kernel/virtio/utils.rs     |  57 ++++++
> > rust/kernel/virtio/virtqueue.rs | 314 +++++++++++++++++++++++++++++
> > samples/rust/Kconfig            |  15 ++
> > samples/rust/Makefile           |   1 +
> > samples/rust/rust_virtio_rtc.rs | 403 ++++++++++++++++++++++++++++++++++++++
> > 13 files changed, 1309 insertions(+), 2 deletions(-)
> >---
> >base-commit: 028ef9c96e96197026887c0f092424679298aae8
> >change-id: 20260504-rust-virtio-8523b01dfdc2
> >
> >Best regards,
> >--
> >Manos Pitsidianakis <[email protected]>
> >
>
>
> --
>
> foo
>