On Wed, Jul 22, 2026 at 11:04 AM Manos Pitsidianakis <[email protected]> wrote: > > Hi Eugenio, > > On Wed, 22 Jul 2026 11:49, Eugenio Perez Martin <[email protected]> wrote: > >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-b3153dd90...@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? > > I think so, however it would not be upstreamable right away since (I > think) there are no netdev Rust bindings and abstractions yet. I will > take a look when I have the time... >
How about starting even smaller? Just with the virtio-ring processing that all virtio drivers share. > (This is something I am also interested in because I'm working on a > different kind of network device) > > You can definitely play with the sample driver included in this series > however! > > Manos > > > > > >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]> > >> > >
