This adds a separate block driver for the bochs image format called 'bochs-rs' so that for the moment both the C implementation and the Rust implementation can be present in the same build. The intention is to remove the C implementation eventually and rename this one into 'bochs'. This can only happen once Rust can be a hard build dependency for QEMU.
Signed-off-by: Kevin Wolf <kw...@redhat.com> --- rust/block/Cargo.toml | 2 +- rust/block/src/bochs.rs | 297 +++++++++++++++++++++++++++++++++++++++ rust/block/src/driver.rs | 5 - rust/block/src/lib.rs | 1 + 4 files changed, 299 insertions(+), 6 deletions(-) create mode 100644 rust/block/src/bochs.rs diff --git a/rust/block/Cargo.toml b/rust/block/Cargo.toml index fbc2f2d6ef..b91483aed1 100644 --- a/rust/block/Cargo.toml +++ b/rust/block/Cargo.toml @@ -3,7 +3,7 @@ name = "block" version = "0.1.0" edition = "2021" authors = ["Kevin Wolf <kw...@redhat.com>"] -license = "GPL-2.0-or-later" +license = "GPL-2.0-or-later AND MIT" readme = "README.md" description = "Block backends for QEMU" repository = "https://gitlab.com/qemu-project/qemu/"; diff --git a/rust/block/src/bochs.rs b/rust/block/src/bochs.rs new file mode 100644 index 0000000000..9dd84446e1 --- /dev/null +++ b/rust/block/src/bochs.rs @@ -0,0 +1,297 @@ +// SPDX-License-Identifier: MIT +/* + * Block driver for the various disk image formats used by Bochs + * Currently only for "growing" type in read-only mode + * + * Copyright (c) 2005 Alex Beregszaszi + * Copyright (c) 2024 Red Hat + * + * Authors: + * Alex Beregszaszi + * Kevin Wolf <kw...@redhat.com> + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +use crate::driver::{block_driver, BdrvChild, BlockDriver, Mapping, MappingTarget, Request}; +use crate::SizedIoBuffer; +use qemu_api::bindings; +use qemu_api::errno::Errno; +use qemu_api::futures::qemu_run_future; +use std::cmp::min; +use std::io::{self, Error, ErrorKind}; +use std::mem::MaybeUninit; +use std::ptr; +use std::sync::Arc; + +const BDRV_SECTOR_SIZE: u64 = 512; + +const HEADER_MAGIC: [u8; 32] = *b"Bochs Virtual HD Image\0\0\0\0\0\0\0\0\0\0"; +const HEADER_VERSION: u32 = 0x00020000; +const HEADER_V1: u32 = 0x00010000; +const HEADER_SIZE: usize = 512; + +const HEADER_TYPE_REDOLOG: [u8; 16] = *b"Redolog\0\0\0\0\0\0\0\0\0"; +const HEADER_SUBTYPE_GROWING: [u8; 16] = *b"Growing\0\0\0\0\0\0\0\0\0"; + +// TODO Use u64.div_ceil() when MSRV is updated to at least 1.73.0 +fn div_ceil(a: u64, b: u64) -> u64 { + (a + b - 1) / b +} + +// TODO Use little endian enforcing type for integers + +#[repr(C, packed)] +struct BochsHeader { + pub magic: [u8; 32], + pub imgtype: [u8; 16], + pub subtype: [u8; 16], + pub version: u32, + pub header_size: u32, + pub catalog_entries: u32, + pub bitmap_size: u32, + pub extent_size: u32, + pub extra: BochsHeaderExtra, +} +unsafe impl SizedIoBuffer for BochsHeader {} + +#[repr(C, packed)] +union BochsHeaderExtra { + v2: BochsHeaderExtraRedolog, + v1: BochsHeaderExtraRedologV1, + padding: [u8; HEADER_SIZE - 84], +} + +#[repr(C, packed)] +#[derive(Clone, Copy)] +struct BochsHeaderExtraRedolog { + pub timestamp: u32, + pub disk_size: u64, +} + +#[repr(C, packed)] +#[derive(Clone, Copy)] +struct BochsHeaderExtraRedologV1 { + pub disk_size: u64, +} + +pub struct BochsImage { + file: Arc<BdrvChild>, + size: u64, + data_offset: u64, + bitmap_blocks: u64, + extent_size: u64, + extent_blocks: u64, + catalog_bitmap: Vec<u32>, // TODO Rename +} + +impl BochsImage { + pub async fn new(file: BdrvChild) -> io::Result<Self> { + let header = file + .read_uninit(0, Box::new(MaybeUninit::<BochsHeader>::uninit())) + .await?; + + if header.magic != HEADER_MAGIC + || header.imgtype != HEADER_TYPE_REDOLOG + || header.subtype != HEADER_SUBTYPE_GROWING + { + return Err(Error::new( + ErrorKind::InvalidInput, + "Image not in Bochs format", + )); + } + + let size = match u32::from_le(header.version) { + HEADER_VERSION => unsafe { header.extra.v2.disk_size.to_le() }, + HEADER_V1 => unsafe { header.extra.v1.disk_size.to_le() }, + _ => return Err(Error::new(ErrorKind::InvalidInput, "Version not supported")), + }; + + let header_size: u64 = header.header_size.to_le().into(); + let extent_size: u64 = header.extent_size.to_le().into(); + + if extent_size < BDRV_SECTOR_SIZE { + // bximage actually never creates extents smaller than 4k + return Err(Error::new( + ErrorKind::InvalidInput, + "Extent size must be at least 512", + )); + } else if !extent_size.is_power_of_two() { + return Err(Error::new( + ErrorKind::InvalidInput, + format!("Extent size {extent_size} is not a power of two"), + )); + } else if extent_size > 0x800000 { + return Err(Error::new( + ErrorKind::InvalidInput, + format!("Extent size {extent_size} is too large"), + )); + } + + // Limit to 1M entries to avoid unbounded allocation. This is what is + // needed for the largest image that bximage can create (~8 TB). + let catalog_entries: usize = header + .catalog_entries + .to_le() + .try_into() + .map_err(|e| Error::new(ErrorKind::InvalidInput, e))?; + if catalog_entries > 0x100000 { + return Err(Error::new(ErrorKind::Other, "Catalog size is too large")); + } else if (catalog_entries as u64) < div_ceil(size, extent_size) { + return Err(Error::new( + ErrorKind::InvalidInput, + "Catalog size is too small for this disk size", + )); + } + + // FIXME This was g_try_malloc() in C + let mut catalog_bitmap = vec![0u32; catalog_entries]; + file.read(header_size, catalog_bitmap.as_mut_slice()) + .await?; + + for entry in &mut catalog_bitmap { + *entry = entry.to_le(); + } + + let data_offset = header_size + (catalog_entries as u64 * 4); + let bitmap_blocks = (1 + (header.bitmap_size.to_le() - 1) / 512).into(); + let extent_blocks = 1 + (extent_size - 1) / 512; + + Ok(Self { + file: Arc::new(file), + size, + data_offset, + bitmap_blocks, + extent_size, + extent_blocks, + catalog_bitmap, + }) + } +} + +impl BlockDriver for BochsImage { + type Options = bindings::BlockdevOptionsGenericFormat; + + unsafe fn parse_options( + v: &mut bindings::Visitor, + opts: &mut *mut Self::Options, + errp: *mut *mut bindings::Error, + ) { + unsafe { + bindings::visit_type_BlockdevOptionsGenericFormat(v, ptr::null(), opts as *mut _, errp); + } + } + + unsafe fn free_options(opts: *mut Self::Options) { + unsafe { + bindings::qapi_free_BlockdevOptionsGenericFormat(opts); + } + } + + unsafe fn open( + bs: *mut bindings::BlockDriverState, + opts: &Self::Options, + errp: *mut *mut bindings::Error, + ) -> std::os::raw::c_int { + let file_child; + unsafe { + /* No write support yet */ + bindings::bdrv_graph_rdlock_main_loop(); + let ret = bindings::bdrv_apply_auto_read_only(bs, ptr::null(), errp); + bindings::bdrv_graph_rdunlock_main_loop(); + if ret < 0 { + return ret; + } + + file_child = match BdrvChild::new(bs, opts.file, errp) { + Some(c) => c, + None => return -libc::EINVAL, + }; + } + + qemu_run_future(async { + match BochsImage::new(file_child).await { + Ok(bdrv) => unsafe { + (*bs).total_sectors = + div_ceil(bdrv.size(), BDRV_SECTOR_SIZE).try_into().unwrap(); + let state = (*bs).opaque as *mut BochsImage; + state.write(bdrv); + 0 + }, + Err(e) => -i32::from(Errno::from(e).0), + } + }) + } + + fn size(&self) -> u64 { + self.size + } + + async fn map(&self, req: &Request) -> io::Result<Mapping> { + let (offset, len) = match *req { + Request::Read { offset, len } => (offset, len), + }; + + let extent_index: usize = (offset / self.extent_size).try_into().unwrap(); + let extent_offset = (offset % self.extent_size) / 512; + + if self.catalog_bitmap[extent_index] == 0xffffffff { + return Ok(Mapping { + offset: (extent_index as u64) * self.extent_size, + len: self.extent_size, + target: MappingTarget::Unmapped, + }); + } + + let bitmap_offset = self.data_offset + + (512 + * (self.catalog_bitmap[extent_index] as u64) + * (self.extent_blocks + self.bitmap_blocks)); + + // Read in bitmap for current extent + // TODO This should be cached + let mut bitmap_entry = 0x8; + self.file + .read(bitmap_offset + (extent_offset / 8), &mut bitmap_entry) + .await?; + + // We checked only a single sector + let offset = offset & !511; + let len = min(len, 512); + + if (bitmap_entry >> (extent_offset % 8)) & 1 == 0 { + return Ok(Mapping { + offset, + len, + target: MappingTarget::Unmapped, + }); + } + + Ok(Mapping { + offset, + len, + target: MappingTarget::Data { + node: self.file.clone(), + offset: bitmap_offset + (512 * (self.bitmap_blocks + extent_offset)), + }, + }) + } +} + +block_driver!("bochs-rs", BochsImage); diff --git a/rust/block/src/driver.rs b/rust/block/src/driver.rs index 022d50ffbc..baeaf47eda 100644 --- a/rust/block/src/driver.rs +++ b/rust/block/src/driver.rs @@ -2,11 +2,6 @@ // Author(s): Kevin Wolf <kw...@redhat.com> // SPDX-License-Identifier: GPL-2.0-or-later -// All of this is unused until the first block driver is added -#![allow(dead_code)] -#![allow(unused_macros)] -#![allow(unused_imports)] - use crate::{IoBuffer, SizedIoBuffer}; use qemu_api::bindings; use qemu_api::errno::Errno; diff --git a/rust/block/src/lib.rs b/rust/block/src/lib.rs index 54ebd480ec..ff528609bc 100644 --- a/rust/block/src/lib.rs +++ b/rust/block/src/lib.rs @@ -1,3 +1,4 @@ +mod bochs; mod driver; mod iobuffer; -- 2.48.1
