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[2620:137:e000::1:20]) by mx.google.com with ESMTP id yk20-20020a17090770d400b009094a93d9b7si1108020ejb.990.2023.04.05.13.40.30; Wed, 05 Apr 2023 13:40:54 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@collabora.com header.s=mail header.b=a9wYqnLa; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=collabora.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234103AbjDEUPK (ORCPT + 99 others); Wed, 5 Apr 2023 16:15:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234629AbjDEUOw (ORCPT ); Wed, 5 Apr 2023 16:14:52 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54AC0659E; Wed, 5 Apr 2023 13:14:44 -0700 (PDT) Received: from localhost.localdomain (unknown [IPv6:2804:14d:72b4:8284:32a8:8167:f815:2895]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dwlsalmeida) by madras.collabora.co.uk (Postfix) with ESMTPSA id 6FD0466030CD; Wed, 5 Apr 2023 21:14:41 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1680725683; bh=+ue2dVx6Skg3DwA+K3zdBvxTsB3ZytSwgxl5p7gxtyU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a9wYqnLaAHqDClTunVyKZbBcPm1FTR8uC8G3YxalJLoY9odl34VM+LXC/h5G3Y2Uj FIJvu2tG2fJkoOuocT1Ue+Gn4GGglNwxXGqGR/49LNV37+2wk9uPlqUv1kaMqQIjlG MbrCfm1VCsupt/RUTCrP/ExAi/bJdYBpytxrdCRhUPbPvTKey0U+sUUvspuHUbnMaH p/c7gMTpfJsXu0+Ec91pP24XNh6cwzp6N+sq6nP7/rQiEfUssb0RZhNaj0rc17uGjE uNLjSAVsOFs1db3rlP2+vhf4uLakBC0PKKgZ8gpE+LNAWdA+y3+muQdu/KY8WRRzPk VZeYn0n2noTqA== From: Daniel Almeida To: wedsonaf@gmail.com, ojeda@kernel.org Cc: Daniel Almeida , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH v2 2/2] rust: virtio: add virtio support Date: Wed, 5 Apr 2023 17:14:16 -0300 Message-Id: <20230405201416.395840-3-daniel.almeida@collabora.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230405201416.395840-1-daniel.almeida@collabora.com> References: <20230405201416.395840-1-daniel.almeida@collabora.com> MIME-Version: 1.0 X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1762369286696377054?= X-GMAIL-MSGID: =?utf-8?q?1762370261213552283?= This patch adds virtIO support to the rust crate. This includes the capability to create a virtIO driver (through the module_virtio_driver macro and the respective Driver trait) as well as initial virtqueue support. A sample virtIO module is included for conveninence. Signed-off-by: Daniel Almeida --- rust/bindings/bindings_helper.h | 3 + rust/helpers.c | 25 +++ rust/kernel/lib.rs | 2 + rust/kernel/virtio.rs | 261 ++++++++++++++++++++++++++++++++ rust/kernel/virtio/virtqueue.rs | 126 +++++++++++++++ samples/rust/Kconfig | 10 ++ samples/rust/Makefile | 1 + samples/rust/rust_virtio.rs | 195 ++++++++++++++++++++++++ 8 files changed, 623 insertions(+) create mode 100644 rust/kernel/virtio.rs create mode 100644 rust/kernel/virtio/virtqueue.rs create mode 100644 samples/rust/rust_virtio.rs diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 048bae2197ac..001a492e0554 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -35,6 +35,9 @@ #include #include #include +#include +#include +#include /* `bindgen` gets confused at certain things. */ const gfp_t BINDINGS_GFP_KERNEL = GFP_KERNEL; diff --git a/rust/helpers.c b/rust/helpers.c index bf790f46c763..a80b0ab8ca64 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -39,6 +39,8 @@ #include #include #include +#include +#include __noreturn void rust_helper_BUG(void) { @@ -655,6 +657,29 @@ int rust_helper_fs_parse(struct fs_context *fc, } EXPORT_SYMBOL_GPL(rust_helper_fs_parse); +struct virtqueue *rust_helper_virtio_find_single_vq(struct virtio_device *vdev, + vq_callback_t *c, + const char *n) +{ + return virtio_find_single_vq(vdev, c, n); +} + +EXPORT_SYMBOL_GPL(rust_helper_virtio_find_single_vq); + +void rust_helper_virtio_del_vqs(struct virtio_device *vdev) +{ + vdev->config->del_vqs(vdev); +} + +EXPORT_SYMBOL_GPL(rust_helper_virtio_del_vqs); + +void rust_helper_virtio_device_ready(struct virtio_device *vdev) +{ + virtio_device_ready(vdev); +} + +EXPORT_SYMBOL_GPL(rust_helper_virtio_device_ready); + /* * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type * as the Rust `usize` type, so we can use it in contexts where Rust diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index b23be69919cc..5441b545c5f2 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -74,6 +74,8 @@ pub mod revocable; pub mod scatterlist; pub mod security; pub mod task; +#[cfg(CONFIG_VIRTIO)] +pub mod virtio; pub mod workqueue; pub mod linked_list; diff --git a/rust/kernel/virtio.rs b/rust/kernel/virtio.rs new file mode 100644 index 000000000000..a95a32605728 --- /dev/null +++ b/rust/kernel/virtio.rs @@ -0,0 +1,261 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Virtio abstractions +//! +//! C header: [`include/linux/virtio.h`](../../../../include/media/virtio.h) + +use crate::{ + device, driver, + error::{self, from_kernel_result}, + prelude::*, + str::CStr, + to_result, ForeignOwnable, ThisModule, +}; + +pub mod virtqueue; + +/// A VirtIO Device ID entry. Safe wrapper over `struct virtio_device_id`. +#[derive(Copy, Clone, Debug, PartialEq, PartialOrd)] +pub struct DeviceId { + /// The device ID in the virtIO protocol. + pub device: u32, + /// The vendor ID, usually set to VIRTIO_DEV_ANY_ID. + pub vendor: u32, +} + +// SAFETY: we ensure that `RawDeviceId::ZERO` is actually a zeroed out version of +// the raw device id. Offset is not needed, because there is no `data` pointer. +unsafe impl const crate::driver::RawDeviceId for DeviceId { + type RawType = bindings::virtio_device_id; + + const ZERO: Self::RawType = bindings::virtio_device_id { + device: 0, + vendor: 0, + }; + + fn to_rawid(&self, _offset: isize) -> Self::RawType { + bindings::virtio_device_id { + device: self.device, + vendor: self.vendor, + } + } +} + +/// Defines a VirtIO ID table consisting of [`DeviceId`] entries. +#[macro_export] +macro_rules! define_virtio_id_table { + ($data_type:ty, $($t:tt)*) => { + $crate::define_id_table!(ID_TABLE, $crate::virtio::DeviceId, $data_type, $($t)*); + }; +} + +/// A registration of a virtio driver. +pub type Registration = driver::Registration>; + +/// An adapter for the registration of virtio drivers. +pub struct Adapter(T); + +impl driver::DriverOps for Adapter { + type RegType = bindings::virtio_driver; + + unsafe fn register( + reg: *mut bindings::virtio_driver, + name: &'static CStr, + _module: &'static ThisModule, + ) -> Result { + // SAFETY: By the safety requirements of this function `reg` is non-null + // and valid. + let virtio_driver = unsafe { &mut *reg }; + + virtio_driver.driver.name = name.as_char_ptr(); + virtio_driver.probe = Some(Self::probe_callback); + virtio_driver.remove = Some(Self::remove_callback); + if let Some(t) = T::ID_TABLE { + virtio_driver.id_table = t.as_ref(); + } + + to_result(unsafe { bindings::register_virtio_driver(reg) }) + } + + unsafe fn unregister(reg: *mut bindings::virtio_driver) { + // SAFETY: By the safety requirements of this function `reg` was passed + // (and updated) by a previous successful call to + // `register_virtio_driver`. + unsafe { bindings::unregister_virtio_driver(reg) }; + } +} + +impl Adapter { + extern "C" fn probe_callback(virtio_device: *mut bindings::virtio_device) -> core::ffi::c_int { + from_kernel_result! { + // SAFETY: `virtio_device` is valid by the contract with the C code. + // `dev` is alive only for the duration of this call, so it is + // guaranteed to remain alive for the lifetime of `virtio_device`. + let mut dev = unsafe { Device::from_ptr(virtio_device) }; + if let Some(data) = T::probe(&mut dev)? { + // SAFETY: `virtio_device` is passed in by the kernel and + // assumed to be valid. + unsafe { (*virtio_device).priv_ = data.into_foreign() as _ } + } + + // Either `probe()` or `device_ready()` must pass Self::Data, as we + // assume `virtio_device.priv_` is set to a valid object throughout + // the code. + // SAFETY: `virtio_device` is passed in by the kernel and + // assumed to be valid. + if !(unsafe { *virtio_device }).priv_.is_null() { + Ok(0) + } else { + Err(EINVAL) + } + } + } + + // Note, this type is a wrapper over a kernel pointer, meaning that we + // cannot be sure that the pointee is actually going away when the wrapper + // is dropped. Thus, release resources here instead, since the kernel will + // call this when the actual pointee is to be removed. + extern "C" fn remove_callback(virtio_device: *mut bindings::virtio_device) { + // SAFETY: `virtio_device` is guaranteed to be a valid, non-null + // pointer. `priv_` was set on `probe()`. + let ptr = unsafe { (*virtio_device).priv_ }; + // SAFETY: + // - We allocated this pointer using `T::Data::into_foreign`, so it is + // safe to turn back into a `T::Data`. + // - The allocation happened in probe()`, no-one freed the memory and + // `remove` is the canonical kernel location to free driver data. So, + // it is OK to convert the pointer back to a Rust structure here. + let data = unsafe { T::Data::from_foreign(ptr) }; + T::remove(&data); + + // SAFETY: just a couple of FFI call with a valid pointer. + unsafe { + bindings::virtio_del_vqs(virtio_device); + bindings::virtio_reset_device(virtio_device); + } + ::device_remove(&data); + } +} + +/// A virtio driver. +pub trait Driver { + /// Data stored on device by driver in `virtio_device.priv` + type Data: ForeignOwnable + Send + Sync + driver::DeviceRemoval = (); + + /// The table of [`DeviceId`]s supported by the driver. + const ID_TABLE: Option> = None; + /// The virtio features offered. This depends on the specifics of the given + /// VirtIO protocol for the device and can be empty. + const FEATURES: &'static [i32] = &[]; + + /// VirtIO driver probe. + /// + /// Called when a new virtio device is added or discovered. + /// Implementers should attempt to initialize the device here. + fn probe(dev: &mut Device) -> Result>; + + /// VirtIO driver remove. + /// + /// Called when a virtio device is removed. + /// Implementers should prepare the device for complete removal here. + /// + /// In particular, implementers must ensure no buffers are left over in the + /// virtqueues in use by calling [`virtqueue::get_buf()`] until `None` is + /// returned. + fn remove(_data: &Self::Data) {} +} + +/// A VirtIO device. +/// +/// # Invariants +/// +/// The field `ptr` is non-null and valid for the lifetime of the object. +pub struct Device { + ptr: *mut bindings::virtio_device, +} + +impl Device { + /// Creates a new device from the given pointer. + /// + /// # Safety + /// + /// `ptr` must be non-null and valid. It must remain valid for the lifetime of the returned + /// instance. + pub unsafe fn from_ptr(ptr: *mut bindings::virtio_device) -> Self { + // INVARIANT: The safety requirements of the function ensure the lifetime invariant. + Self { ptr } + } + + /// Returns id of the VirtIO device. + pub fn id(&self) -> i32 { + // SAFETY: By the type invariants, we know that `self.ptr` is non-null and valid. + unsafe { (*self.ptr).id.device as _ } + } + + /// Returns the `Virtqueue` associated with `name`, if any. + pub fn find_virtqueue( + &self, + name: &CStr, + ) -> Result> { + let callback = if T::HAS_CALLBACK { + Some(virtqueue::Virtqueue::::vq_callback as _) + } else { + None + }; + + // SAFETY: ptr is valid due to the type invariant, callback points to a + // valid address and the pointer passed in is passed in by the kernel, + // so it is assumed to be valid. + let vq = unsafe { bindings::virtio_find_single_vq(self.ptr, callback, name.as_char_ptr()) }; + let vq = error::from_kernel_err_ptr(vq)?; + + // SAFETY: vq is checked with `from_kernel_err_ptr` + Ok(unsafe { virtqueue::Virtqueue::from_ptr(vq) }) + } + + /// Returns the Virtio Device's private data. + pub fn data(&self) -> ::Borrowed<'_> { + unsafe { ::borrow((*self.ptr).priv_) } + } + + /// Returns a pointer to the [`bindings::virtio_device`] associated with + /// this [`Device`]. + pub fn raw_device(&self) -> *mut bindings::virtio_device { + self.ptr + } + + /// Wrapper over the C-side `virtio_device_ready`. Enable virtqueue use in + /// the probe function. Drivers must call this to use virtqueues in the + /// probe function. + /// + /// `data` can be optionally be set through `device_ready()` instead of + /// `probe()`. + pub fn device_ready(&self, data: Option) { + if let Some(data) = data { + // SAFETY: `virtio_device` is passed in by the kernel and + // assumed to be valid. + unsafe { (*self.ptr).priv_ = data.into_foreign() as _ } + } + + // SAFETY: just a FFI call on a valid pointer. + unsafe { + bindings::virtio_device_ready(self.ptr); + } + } +} + +// SAFETY: The device returned by `raw_device` is the raw virtio device. +unsafe impl device::RawDevice for Device { + fn raw_device(&self) -> *mut bindings::device { + // SAFETY: By the type invariants, we know that `self.ptr` is non-null and valid. + unsafe { &mut (*self.ptr).dev } + } +} + +/// Declares a kernel module that exposes a single virtio driver. +#[macro_export] +macro_rules! module_virtio_driver { + ($($f:tt)*) => { + $crate::module_driver!(, $crate::virtio::Adapter, { $($f)* }); + }; +} diff --git a/rust/kernel/virtio/virtqueue.rs b/rust/kernel/virtio/virtqueue.rs new file mode 100644 index 000000000000..a735f3d997a9 --- /dev/null +++ b/rust/kernel/virtio/virtqueue.rs @@ -0,0 +1,126 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Virtqueue abstractions. +//! +//! C header: [`include/linux/virtio.h`](../../../../include/linux/virtio.h) + +use core::marker::PhantomData; + +use crate::error; +use crate::prelude::*; +use crate::scatterlist::Scatterlist; +use crate::virtio; +use crate::ForeignOwnable; + +/// The Virtqueue's operations. +#[vtable] +pub trait Operations: Sized { + /// Data passed into the callback. + type PrivateData: ForeignOwnable; + + /// The virtqueue callback. + fn callback(virtqueue: Virtqueue); +} + +/// A Virtqueue abstraction. +pub struct Virtqueue { + /// The underlying pointer. + ptr: *mut bindings::virtqueue, + /// A Phantom so T gets used. + phantom: PhantomData, +} + +impl Virtqueue { + /// # Safety + /// The caller must ensure that `ptr` is valid and remains valid for the lifetime of the + /// returned [`Virtqueue`] instance. + /// + /// Caller must ensure that get_buf() returns None before the Virtqueue is + /// dropped, so that ownership of the passed in T::PrivateData can be + /// retrieved. + pub unsafe fn from_ptr(ptr: *mut bindings::virtqueue) -> Self { + Self { + ptr, + phantom: PhantomData, + } + } + + /// A wrapper over the C side `virtqueue_add_sgs()`. Adds scatterlists to + /// the [`Virtqueue`] for processing. + pub fn add_sgs( + &mut self, + out_sgs: &mut [Scatterlist], + in_sgs: &mut [Scatterlist], + data: T::PrivateData, + gfp: u32, + ) -> Result { + let mut sgs = Vec::new(); + + let num_out = out_sgs.len(); + let num_in = in_sgs.len(); + + for s in out_sgs { + sgs.try_push(s.inner().get())?; + } + for s in in_sgs { + sgs.try_push(s.inner().get())?; + } + + // SAFETY: `self.ptr` is valid as per the type invariant. + let res = unsafe { + bindings::virtqueue_add_sgs( + self.ptr, + sgs.as_mut_ptr(), + num_out as u32, + num_in as u32, + data.into_foreign() as _, + gfp, + ) + }; + + error::to_result(res) + } + + /// A wrapper over the C side `virtqueue_kick()`. Notifies the VirtIO device + /// of activity in this [`Virtqueue`]. + pub fn kick(&mut self) -> Result { + let res = unsafe { bindings::virtqueue_kick(self.ptr) }; + error::to_result(res as i32) + } + + /// Returns the underlying [`virtio::Device`]. + pub fn virtio_device(&self) -> virtio::Device { + // SAFETY: The virtio framework places a pointer to the VirtIO device + // when creating the virtqueue + unsafe { virtio::Device::from_ptr((*self.ptr).vdev) } + } + + /// A wrapper over the C side `virtqueue_get_buf()`. Returns the next used + /// buffer, if any, alongside with the amount of data written. + pub fn get_buf(&mut self) -> Option<(T::PrivateData, u32)> { + let mut len = 0; + + let data = unsafe { + let buf = bindings::virtqueue_get_buf(self.ptr, &mut len as _); + + if buf.is_null() { + return None; + } + + // SAFETY: if there is a buffer token, it came from + // `into_foreign()` as called in `add_sgs()`. + ::from_foreign(buf) + }; + + Some((data, len)) + } + + pub(crate) unsafe extern "C" fn vq_callback(vq: *mut bindings::virtqueue) { + // SAFETY: the caller should guarantee that `vq` is valid for the lifetime + // of `Self`. + let virtqueue = unsafe { Self::from_ptr(vq) }; + T::callback(virtqueue); + } +} + +unsafe impl Send for Virtqueue {} diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig index 189c10ced6d4..0507c57170ec 100644 --- a/samples/rust/Kconfig +++ b/samples/rust/Kconfig @@ -163,4 +163,14 @@ config SAMPLE_RUST_SELFTESTS If unsure, say N. +config SAMPLE_RUST_VIRTIO + tristate "Virtio" + help + This option builds the Rust virtio module sample. + + To compile this as a module, choose M here: + the module will be called rust_minimal. + + If unsure, say N. + endif # SAMPLES_RUST diff --git a/samples/rust/Makefile b/samples/rust/Makefile index 420bcefeb082..24059795480f 100644 --- a/samples/rust/Makefile +++ b/samples/rust/Makefile @@ -15,5 +15,6 @@ obj-$(CONFIG_SAMPLE_RUST_NETFILTER) += rust_netfilter.o obj-$(CONFIG_SAMPLE_RUST_ECHO_SERVER) += rust_echo_server.o obj-$(CONFIG_SAMPLE_RUST_FS) += rust_fs.o obj-$(CONFIG_SAMPLE_RUST_SELFTESTS) += rust_selftests.o +obj-$(CONFIG_SAMPLE_RUST_VIRTIO) += rust_virtio.o subdir-$(CONFIG_SAMPLE_RUST_HOSTPROGS) += hostprogs diff --git a/samples/rust/rust_virtio.rs b/samples/rust/rust_virtio.rs new file mode 100644 index 000000000000..fddab8674909 --- /dev/null +++ b/samples/rust/rust_virtio.rs @@ -0,0 +1,195 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Rust virtio device driver sample. Retrieves a random number from the guest +//! using VirtIO Entropy. + +// impl_self_work_adapter!() does not compile otherwise. +#![allow(unreachable_code)] + +use kernel::bindings; +use kernel::module_virtio_driver; +use kernel::prelude::*; +use kernel::scatterlist; +use kernel::sync::smutex::Mutex; +use kernel::sync::Arc; +use kernel::sync::UniqueArc; +use kernel::virtio::virtqueue; +use kernel::virtio::virtqueue::Virtqueue; +use kernel::workqueue; +use kernel::Opaque; + +module_virtio_driver! { + type: Driver, + name: "rust_virtio", + license: "GPL", +} + +struct AckWork { + work: workqueue::Work, + raw_dev: *mut kernel::bindings::virtio_device, +} + +impl AckWork { + pub(crate) fn new(raw_dev: *mut kernel::bindings::virtio_device) -> Result> { + let work = UniqueArc::try_new(Self { + // SAFETY: init_work_item!() is called below + work: unsafe { workqueue::Work::new() }, + raw_dev, + })?; + + kernel::init_work_item!(&work); + + Ok(work.into()) + } +} + +kernel::impl_self_work_adapter!(AckWork, work, |w| { + // SAFETY: + // + // If the work still exists, the driver data still exists (as it is its + // sole owner). + // + // If the driver data still exisits, then the underlying kernel::Device + // is alive (as it holds a reference obtained from get_device()) + // + // If the contained struct device* is alive, the outermost struct + // virtio_device* is presumed alive and valid. + // + // Other virtio drivers (in C) just use container_of here as they embed + // the work struct in their driver struct itself. + let virtio_dev = unsafe { kernel::virtio::Device::from_ptr(w.raw_dev) }; + let virtio_device_data = virtio_dev.data::(); + + let mut vq = virtio_device_data.vq.lock(); + + if let Some(resp) = vq.get_buf() { + pr_crit!("Retrieving response, host wrote {} bytes", resp.1); + // SAFETY: Just a FFI call on a completion that was previously + // initialized with `init_completion`. + unsafe { bindings::complete(resp.0.completion.get()) } + } +}); + +// SAFETY: the fields are not exposed. Nothing can be done. +unsafe impl Send for AckWork {} +unsafe impl Sync for AckWork {} + +struct Request { + inner: Mutex, + completion: Opaque, +} + +struct RequestInner { + data: [u8; 64], +} + +fn send_request( + vq: &Mutex>, + request: ::PrivateData, +) -> Result { + let mut inner_guard = request.inner.lock(); + // SAFETY: inner_guard.data points to an owned array, buflen is the size of + // the array. + let mut in_sgs = unsafe { + [scatterlist::Scatterlist::init_one( + inner_guard.data.as_mut_ptr() as *mut core::ffi::c_void, + core::mem::size_of_val(&inner_guard.data) as u32, + )] + }; + + // SAFETY: Just a FFI call on a valid bindgen type. + unsafe { bindings::init_completion(request.completion.get()) } + + { + let mut vq = vq.lock(); + let mut out_sgs = []; + vq.add_sgs( + &mut out_sgs[..], + &mut in_sgs[..], + Arc::clone(&request), + bindings::GFP_KERNEL, + )?; + + vq.kick()?; + } + + pr_crit!("Request sent, waiting"); + + // SAFETY: Just a FFI call on a valid bindgen type that was previously + // passed to `init_completion`. + unsafe { bindings::wait_for_completion(request.completion.get()) } + + pr_crit!("Request completed, response was {:?}", inner_guard.data); + Ok(()) +} + +struct Driver { + /// The virtqueue. + vq: Mutex>, + /// The ack work that is awaken by the ack callback. + work: Arc, +} + +impl kernel::driver::DeviceRemoval for Driver { + fn device_remove(&self) { + let mut vq = self.vq.lock(); + while let Some(_buf) = vq.get_buf() { + // Actual drivers should take care to retrieve any left over buffers + // so `T::PrivateData` can drop. + } + } +} + +impl kernel::virtio::Driver for Driver { + type Data = Arc; + + kernel::define_virtio_id_table! {(), [ + (kernel::virtio::DeviceId { + device: bindings::VIRTIO_ID_RNG, + vendor: bindings::VIRTIO_DEV_ANY_ID, + }, None), + ]} + + fn probe(virtio_dev: &mut kernel::virtio::Device) -> Result> { + pr_info!("rust_virtio: probing"); + + let vq = virtio_dev.find_virtqueue::(kernel::c_str!("input"))?; + let vq = Mutex::new(vq); + + let work = AckWork::new(virtio_dev.raw_device())?; + let data = Arc::try_new(Self { vq, work })?; + + // We want to use the virtqueues here in this example. + virtio_dev.device_ready::(Some(Arc::clone(&data))); + + let request = Arc::try_new(Request { + inner: Mutex::new(RequestInner { data: [0; 64] }), + completion: Opaque::new(Default::default()), + })?; + + send_request(&data.vq, Arc::clone(&request))?; + + pr_info!("rust_virtio probed succesfully!"); + + Ok(None) + } +} + +pub(crate) struct VirtqueueCallback; + +#[vtable] +impl virtqueue::Operations for VirtqueueCallback { + type PrivateData = Arc; + + fn callback(vq: Virtqueue) { + let vdev = vq.virtio_device(); + let data = vdev.data::(); + let data = &*data; + + pr_info!("virtqueue callback called successfully!"); + + // Enqueue work in order to retrieve the data and complete the + // completion. + kernel::workqueue::system().enqueue(Arc::clone(&data.work)); + } +}