From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A85401A76DA for ; Wed, 6 Aug 2025 20:51:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754513476; cv=none; b=KKTPXFMTl6ItvL77Ey6w35NY1sxCFu6NvLmZedjULOSxdJMfporztbporyIfkGh1bQQ57DdBpBzW8TH/l2+29UnT3oNLz6v7nyFGEJThILUWEurXjzEsX/E89kMmiXXRp44BEVhhr5jTExNW467pTL99cm/T6R9kL2xz3OxY334= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754513476; c=relaxed/simple; bh=5cF0OrHGUzGN3wlLpdhW1mvM7+ctb+grtocyPMLDD+U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hzGQ1BW0FzzsNhUqXe0ltBN6bqgf/zljz7+WfYAUGY5cN+7xnYvOYx8BemsdnnfDJl+BFi7LILU5LjdIGVwzTUnjvQcIP7cI9qE0PcUsWP2o8PcksHV2lWt0VlLaCfH2QrH4CxpRtiWa2JhU5vmg2EDJ5yvC2JGdjWK0DBr4pj0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AJJneRdl; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="AJJneRdl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8193CC4CEE7; Wed, 6 Aug 2025 20:51:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754513476; bh=5cF0OrHGUzGN3wlLpdhW1mvM7+ctb+grtocyPMLDD+U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AJJneRdljlYBlnVhhYCbqlDh8Mm1RuDoU2OFDSrnNE6gOlfhRWt229gcJesC4IR21 ae13pG/l/OBOe7vokLAr74DWpuPD8UxjFezj1jPUXYDvhy7mmbnSDByBU5u4fR9FjE Nr1prrbYDeREYOEXDYyGMJ2pjL9ucZV45Ci+yUiFHOA2XgLfO4TI07HwO5xEPlIC+g lQ4NVe4hwe+P1oAPvXRSe0tHEtzKWd0RzZX3pz5O6BfjPp6vBWYECfh/rwG9qiTuqk EPIdZQK3kXZbyuZn+totK9BJFVY7bWli7wU+Jlcn/pSKMaNnEzEUXm3RyGxWvOwKJJ kTCk+5gSMwe8A== From: Danilo Krummrich To: lorenzo.stoakes@oracle.com, vbabka@suse.cz, Liam.Howlett@oracle.com, urezki@gmail.com, ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, abdiel.janulgue@gmail.com, acourbot@nvidia.com Cc: rust-for-linux@vger.kernel.org, Danilo Krummrich Subject: [PATCH v2 5/6] rust: alloc: kbox: implement PageOwner for VBox Date: Wed, 6 Aug 2025 22:50:14 +0200 Message-ID: <20250806205044.85085-6-dakr@kernel.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250806205044.85085-1-dakr@kernel.org> References: <20250806205044.85085-1-dakr@kernel.org> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Implement the PageOwner trait for VBox; it allows to iterate and borrow the backing pages of a VBox. This, for instance, is useful in combination with VBox backing a scatterlist. Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kbox.rs | 42 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs index 856d05aa60f1..bcca798d466b 100644 --- a/rust/kernel/alloc/kbox.rs +++ b/rust/kernel/alloc/kbox.rs @@ -18,6 +18,7 @@ use crate::ffi::c_void; use crate::init::InPlaceInit; +use crate::page; use crate::types::ForeignOwnable; use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption}; @@ -598,3 +599,44 @@ fn drop(&mut self) { unsafe { A::free(self.0.cast(), layout) }; } } + +/// # Examples +/// +/// ``` +/// # use kernel::{page, prelude::*}; +/// use kernel::page::PageOwner; +/// +/// let mut vbox = VBox::<[u8; page::PAGE_SIZE]>::new_uninit(GFP_KERNEL)?; +/// +/// let page = vbox.page_iter().next().expect("At least one page should be available.\n"); +/// +/// // SAFETY: There is no concurrent read or write to the same page. +/// unsafe { page.fill_zero_raw(0, page::PAGE_SIZE)? }; +/// # Ok::<(), Error>(()) +/// ``` +impl page::PageOwner for VBox { + fn page_iter<'a>(&'a mut self) -> impl Iterator> { + (0..self.page_count()).map(|idx| { + let ptr = self.0.as_ptr().cast::(); + + // TODO: Use `NonNull::add()` instead, once the minimum supported compiler version is + // bumped to 1.80 or later. + // + // SAFETY: `idx` is in the interval `[0, self.page_count())`, hence the resulting + // pointer is guaranteed to be within the same allocation. + let ptr = unsafe { ptr.add(idx * page::PAGE_SIZE) }; + + // SAFETY: `ptr` is guaranteed to be non-null given that it is derived from `self.0`. + let ptr = unsafe { NonNull::new_unchecked(ptr) }; + + // SAFETY: + // - `ptr` is a valid pointer to a `Vmalloc` allocation. + // - `ptr` is valid for the duration of `'a`. + unsafe { Vmalloc::to_page(ptr) } + }) + } + + fn page_count(&self) -> usize { + core::mem::size_of::().div_ceil(page::PAGE_SIZE) + } +} -- 2.50.1