From patchwork Tue Feb 11 21:43:26 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13970756 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 70366C0219B for ; Tue, 11 Feb 2025 21:49:30 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1thy7k-00055P-0I; Tue, 11 Feb 2025 16:48:56 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1thy3d-00082q-3F for qemu-devel@nongnu.org; Tue, 11 Feb 2025 16:44:44 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1thy3b-0005SX-8S for qemu-devel@nongnu.org; Tue, 11 Feb 2025 16:44:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739310278; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=haheJ5bpjRBjbwxH7eaaz7CF0vcGhATS04334Z3InTo=; b=N180bO5TvpogyNy0fNL27rpGyWKa8Kc2qEA08bTxvNGT9MYND7py8CDV1QrDzAKtdbAi33 qkhHm6f/IA1bazpBDqcgSug4bKMw3Awnw2DIkTWQkZUZMVbLbcYe0GFDXdn3qPZYnCsqZW Av1N1xiJ+tW5zBpBKI7eqCrB6NGc+hQ= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-231-kYVvKMFWPDibMpEgJQxqQA-1; Tue, 11 Feb 2025 16:44:34 -0500 X-MC-Unique: kYVvKMFWPDibMpEgJQxqQA-1 X-Mimecast-MFC-AGG-ID: kYVvKMFWPDibMpEgJQxqQA Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BAEA31800874; Tue, 11 Feb 2025 21:44:32 +0000 (UTC) Received: from merkur.redhat.com (unknown [10.44.32.210]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6A6D7195608D; Tue, 11 Feb 2025 21:44:30 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, hreitz@redhat.com, pbonzini@redhat.com, manos.pitsidianakis@linaro.org, qemu-devel@nongnu.org, qemu-rust@nongnu.org Subject: [PATCH 09/11] rust/block: Add read support for block drivers Date: Tue, 11 Feb 2025 22:43:26 +0100 Message-ID: <20250211214328.640374-10-kwolf@redhat.com> In-Reply-To: <20250211214328.640374-1-kwolf@redhat.com> References: <20250211214328.640374-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.54, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org This adds a map() function to the BlockDriver trait and makes use of it to implement reading from an image. Signed-off-by: Kevin Wolf --- rust/block/src/driver.rs | 100 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) diff --git a/rust/block/src/driver.rs b/rust/block/src/driver.rs index 5c7c46bfa0..2849ef6949 100644 --- a/rust/block/src/driver.rs +++ b/rust/block/src/driver.rs @@ -9,11 +9,46 @@ use crate::{IoBuffer, SizedIoBuffer}; use qemu_api::bindings; +use qemu_api::futures::qemu_co_run_future; +use std::cmp::min; use std::ffi::c_void; use std::io::{self, Error, ErrorKind}; use std::mem::MaybeUninit; use std::ptr; +/// A request to a block driver +pub enum Request { + Read { offset: u64, len: u64 }, +} + +/// The target for a number of guest blocks, e.g. a location in a child node or the information +/// that the described blocks are unmapped. +// FIXME Actually use node +#[allow(dead_code)] +pub enum MappingTarget { + /// The described blocks are unallocated. Reading from them yields zeros. + Unmapped, + + /// The described blocks are stored in a child node. + Data { + /// Child node in which the data is stored + node: (), + + /// Offset in the child node at which the data is stored + offset: u64, + }, +} + +/// A mapping for a number of contiguous guest blocks +pub struct Mapping { + /// Offset of the mapped blocks from the perspective of the guest + pub offset: u64, + /// Length of the mapping in bytes + pub len: u64, + /// Where the data for the described blocks is stored + pub target: MappingTarget, +} + /// A trait for writing block drivers. /// /// Types that implement this trait can be registered as QEMU block drivers using the @@ -37,6 +72,11 @@ unsafe fn open( /// Returns the size of the image in bytes fn size(&self) -> u64; + + /// Returns the mapping for the first part of `req`. If the returned mapping is shorter than + /// the request, the function can be called again with a shortened request to get the mapping + /// for the remaining part. + async fn map(&self, req: &Request) -> io::Result; } /// Represents the connection between a parent and its child node. @@ -161,6 +201,65 @@ pub async fn read_uninit( } } +#[doc(hidden)] +pub unsafe extern "C" fn bdrv_co_preadv_part( + bs: *mut bindings::BlockDriverState, + offset: i64, + bytes: i64, + qiov: *mut bindings::QEMUIOVector, + mut qiov_offset: usize, + flags: bindings::BdrvRequestFlags, +) -> std::os::raw::c_int { + let s = unsafe { &mut *((*bs).opaque as *mut D) }; + + let mut offset = offset as u64; + let mut bytes = bytes as u64; + + while bytes > 0 { + let req = Request::Read { offset, len: bytes }; + let mapping = match qemu_co_run_future(s.map(&req)) { + Ok(mapping) => mapping, + Err(e) => { + return e + .raw_os_error() + .unwrap_or(-(bindings::EIO as std::os::raw::c_int)) + } + }; + + let mapping_offset = offset - mapping.offset; + let cur_bytes = min(bytes, mapping.len - mapping_offset); + + match mapping.target { + MappingTarget::Unmapped => unsafe { + bindings::qemu_iovec_memset(qiov, qiov_offset, 0, cur_bytes.try_into().unwrap()); + }, + MappingTarget::Data { + node: _, + offset: target_offset, + } => unsafe { + // TODO Support using child nodes other than bs->file + let ret = bindings::bdrv_co_preadv_part( + (*bs).file, + (target_offset + mapping_offset) as i64, + cur_bytes as i64, + qiov, + qiov_offset, + flags, + ); + if ret < 0 { + return ret; + } + }, + } + + offset += cur_bytes; + qiov_offset += cur_bytes as usize; + bytes -= cur_bytes; + } + + 0 +} + /// Declare a format block driver. This macro is meant to be used at the top level. /// /// `typ` is a type implementing the [`BlockDriver`] trait to handle the image format with the @@ -174,6 +273,7 @@ macro_rules! block_driver { instance_size: ::std::mem::size_of::<$typ>() as i32, bdrv_open: Some($crate::driver::bdrv_open::<$typ>), bdrv_close: Some($crate::driver::bdrv_close::<$typ>), + bdrv_co_preadv_part: Some($crate::driver::bdrv_co_preadv_part::<$typ>), bdrv_child_perm: Some(::qemu_api::bindings::bdrv_default_perms), is_format: true, ..::qemu_api::zeroable::Zeroable::ZERO