From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.nessuent.net (mail.nessuent.net [188.245.177.90]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C0C63397343 for ; Wed, 22 Jul 2026 09:04:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=188.245.177.90 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784711090; cv=none; b=ucNrsvAeCe6+LhDFqOCKWpXvzt9ARKF7L4qhHWspR/D4yYKrwpJ/vZAV9zU6TTkXremqECI2v8fm4Gj+BxP1/7NmaOBWEkuWx8OvdY2yX6sEt/3N+97H74jmzGb/QumgDImnDt+ppuURxKIHFH57/wN5xfTSclBIBPhZWTAPQLg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784711090; c=relaxed/simple; bh=nLONFvR+hxddFQZ/FVj8V6OR3cXh5kdwnHjhpOXWcvA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:Message-ID: MIME-Version:Content-Type; b=PH0wZ2RQ0y+qOrK7v8Oh3/16aMrRfFAIGI02v+ylGEwt04xAhWE/QDrbac+hHwtcRHyhO8BMCCBZdSCUl0E3B1E/kebERANVg6dwqUuYYd6VvFqhsyYbn5blhkXAbpGrgivCLepFkBkdbYUO4T0h/Q36Gi8hqG5y3rF4ol1EJbs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=pitsidianak.is; spf=pass smtp.mailfrom=pitsidianak.is; dkim=pass (4096-bit key) header.d=pitsidianak.is header.i=@pitsidianak.is header.b=sz9NSR/i; arc=none smtp.client-ip=188.245.177.90 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=pitsidianak.is Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pitsidianak.is Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=pitsidianak.is header.i=@pitsidianak.is header.b="sz9NSR/i" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=pitsidianak.is; s=mailSelector; t=1784711078; bh=nLONFvR+hxddFQZ/FVj8V6OR3cXh5kdwnHjhpOXWcvA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From:Subject; b=sz9NSR/i+NOilUL0upXbf1ZeMum/0hNILnqoQICHbxSyD8FZID9bLsEUmbHCxYIRi 79RKfQZwo8DtkIcawo2akDduhkXuDvUnPpEK6SPSlyJNr9ZeTv+KQRW9Xr30/rll++ lS79qEp3gg6qLiHslV92FLWovie83D7nRM8/CN6GJfJg+t4ZCz+OmhVUP8YAFh9vSm YEuXdOn0X6O0rfk3yqfY7MVdv2NIgjf94TcUbRXrAFkEdWYF18gPrLs1u9Ufjamr0e pWrozlj5YjU/bUIOfb69ov0qZCTn/67iphEvdd4foX0pnZbSZ8NIOTswpwX/rClRO+ b3odD/2uXCyD8TbZoOKrSx3Kf8xucAVYpyzwmf7XYjdcaTB4HUEfNBusS3Un7i6G3w ndJogMUYpFOowTx7mkL95kMNEUvg0s1LGq7TIh4gH+ECyQAJbz4XsQqar6LpFi3h7/ 5FDkaqHk0ZZX8LNekBsm112kiegRLjnAod4AGvZWxJWl0ZkSt33BH3rG2JcAlSdI0k R6UVJ4ZW/h6jReIBtqA0P3VKwFKcWAsmQP8onOsXCxU47p5sAJ+QcFXHj9zJe7G9Yj walefsGfJeyy4vcU2BjNosn+NX4hw8EFJtfMt89YhZ/OTgg/8jmWPXEfFOlOMfoB9R 52tiMLSeGBlqr0JRmxqM5/Tc= Date: Wed, 22 Jul 2026 11:55:57 +0300 From: Manos Pitsidianakis To: Eugenio Perez Martin Cc: "Michael S. Tsirkin" , Manos Pitsidianakis , Peter Hilber , Stefano Garzarella , Stefan Hajnoczi , Viresh Kumar , Miguel Ojeda , Boqun Feng , Gary Guo , Bj=?UTF-8?B?w7Zybg==?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , rust-for-linux@vger.kernel.org, Jason Wang , Xuan Zhuo , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC v3 0/6] Add Rust virtio bindings and sample device User-Agent: meli/0.8.13 References: <20260510-rust-virtio-v3-0-1427f14d67e1@pitsidianak.is> In-Reply-To: Message-ID: Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=utf-8; format=flowed Hi Eugenio, On Wed, 22 Jul 2026 11:49, Eugenio Perez Martin wrote: >On Tue, Jul 21, 2026 at 8:24 AM Manos Pitsidianakis > 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? 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... (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 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 >> >--- >> >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/20260509-rust-virtio-v2-0-c1e30ec2bd21@pitsidianak.is >> > >> >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 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/20260505-rust-virtio-v1-0-9563383909e4@pitsidianak.is >> > >> >--- >> >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 >> >