virtualizationservice/vfio_handler/src/aidl.rs - android_packages_modules_Virtualization - Gitiles

 // Copyright 2023, The Android Open Source Project
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 //! Implementation of the AIDL interface of the VirtualizationService.

 use anyhow::{anyhow, Context};
 use android_system_virtualizationservice_internal::aidl::android::system::virtualizationservice_internal::IBoundDevice::{IBoundDevice, BnBoundDevice};
 use android_system_virtualizationservice_internal::aidl::android::system::virtualizationservice_internal::IVfioHandler::IVfioHandler;
 use android_system_virtualizationservice_internal::aidl::android::system::virtualizationservice_internal::IVfioHandler::VfioDev::VfioDev;
 use android_system_virtualizationservice_internal::binder::ParcelFileDescriptor;
 use binder::{self, BinderFeatures, ExceptionCode, Interface, IntoBinderResult, Strong};
 use lazy_static::lazy_static;
 use log::error;
 use std::fs::{read_link, write, File};
 use std::io::{Read, Seek, SeekFrom, Write};
 use std::mem::size_of;
 use std::path::{Path, PathBuf};
 use rustutils::system_properties;
 use zerocopy::{
     byteorder::{BigEndian, U32},
     FromZeroes,
     FromBytes,
 };

 // Device bound to VFIO driver.
 struct BoundDevice {
     sysfs_path: String,
     dtbo_label: String,
 }

 impl Interface for BoundDevice {}

 impl IBoundDevice for BoundDevice {
     fn getSysfsPath(&self) -> binder::Result<String> {
         Ok(self.sysfs_path.clone())
     }

     fn getDtboLabel(&self) -> binder::Result<String> {
         Ok(self.dtbo_label.clone())
     }
 }

 impl Drop for BoundDevice {
     fn drop(&mut self) {
         unbind_device(Path::new(&self.sysfs_path)).unwrap_or_else(|e| {
             error!("did not restore {} driver: {}", self.sysfs_path, e);
         });
     }
 }

 impl BoundDevice {
     fn new_binder(sysfs_path: String, dtbo_label: String) -> Strong<dyn IBoundDevice> {
         BnBoundDevice::new_binder(BoundDevice { sysfs_path, dtbo_label }, BinderFeatures::default())
     }
 }

 #[derive(Debug, Default)]
 pub struct VfioHandler {}

 impl VfioHandler {
     pub fn init() -> VfioHandler {
         VfioHandler::default()
     }
 }

 impl Interface for VfioHandler {}

 impl IVfioHandler for VfioHandler {
     fn bindDevicesToVfioDriver(
         &self,
         devices: &[VfioDev],
     ) -> binder::Result<Vec<Strong<dyn IBoundDevice>>> {
         // permission check is already done by IVirtualizationServiceInternal.
         if !*IS_VFIO_SUPPORTED {
             return Err(anyhow!("VFIO-platform not supported"))
                 .or_binder_exception(ExceptionCode::UNSUPPORTED_OPERATION);
         }
         devices
             .iter()
             .map(|d| {
                 bind_device(Path::new(&d.sysfsPath))?;
                 Ok(BoundDevice::new_binder(d.sysfsPath.clone(), d.dtboLabel.clone()))
             })
             .collect::<binder::Result<Vec<_>>>()
     }

     fn writeVmDtbo(&self, dtbo_fd: &ParcelFileDescriptor) -> binder::Result<()> {
         let dtbo_path = get_dtbo_img_path()?;
         let mut dtbo_img = File::open(dtbo_path)
             .context("Failed to open DTBO partition")
             .or_service_specific_exception(-1)?;

         let dt_table_header = get_dt_table_header(&mut dtbo_img)?;
         let vm_dtbo_idx = system_properties::read("ro.boot.hypervisor.vm_dtbo_idx")
             .context("Failed to read vm_dtbo_idx")
             .or_service_specific_exception(-1)?
             .ok_or_else(|| anyhow!("vm_dtbo_idx is none"))
             .or_service_specific_exception(-1)?;
         let vm_dtbo_idx = vm_dtbo_idx
             .parse()
             .context("vm_dtbo_idx is not an integer")
             .or_service_specific_exception(-1)?;
         let dt_table_entry = get_dt_table_entry(&mut dtbo_img, &dt_table_header, vm_dtbo_idx)?;
         write_vm_full_dtbo_from_img(&mut dtbo_img, &dt_table_entry, dtbo_fd)?;
         Ok(())
     }
 }

 const DEV_VFIO_PATH: &str = "/dev/vfio/vfio";
 const SYSFS_PLATFORM_DEVICES_PATH: &str = "/sys/devices/platform/";
 const VFIO_PLATFORM_DRIVER_PATH: &str = "/sys/bus/platform/drivers/vfio-platform";
 const SYSFS_PLATFORM_DRIVERS_PROBE_PATH: &str = "/sys/bus/platform/drivers_probe";
 const DT_TABLE_MAGIC: u32 = 0xd7b7ab1e;
 const VFIO_PLATFORM_DRIVER_NAME: &str = "vfio-platform";
 // To remove the override and match the device driver by "compatible" string again,
 // driver_override file must be cleared. Writing an empty string (same as
 // `echo -n "" > driver_override`) won't' clear the file, so append a newline char.
 const DEFAULT_DRIVER: &str = "\n";

 /// The structure of DT table header in dtbo.img.
 /// https://source.android.com/docs/core/architecture/dto/partitions
 #[repr(C)]
 #[derive(Debug, FromZeroes, FromBytes)]
 struct DtTableHeader {
     /// DT_TABLE_MAGIC
     magic: U32<BigEndian>,
     /// includes dt_table_header + all dt_table_entry and all dtb/dtbo
     _total_size: U32<BigEndian>,
     /// sizeof(dt_table_header)
     header_size: U32<BigEndian>,
     /// sizeof(dt_table_entry)
     dt_entry_size: U32<BigEndian>,
     /// number of dt_table_entry
     dt_entry_count: U32<BigEndian>,
     /// offset to the first dt_table_entry from head of dt_table_header
     dt_entries_offset: U32<BigEndian>,
     /// flash page size we assume
     _page_size: U32<BigEndian>,
     /// DTBO image version, the current version is 0. The version will be
     /// incremented when the dt_table_header struct is updated.
     _version: U32<BigEndian>,
 }

 /// The structure of each DT table entry (v0) in dtbo.img.
 /// https://source.android.com/docs/core/architecture/dto/partitions
 #[repr(C)]
 #[derive(Debug, FromZeroes, FromBytes)]
 struct DtTableEntry {
     /// size of each DT
     dt_size: U32<BigEndian>,
     /// offset from head of dt_table_header
     dt_offset: U32<BigEndian>,
     /// optional, must be zero if unused
     _id: U32<BigEndian>,
     /// optional, must be zero if unused
     _rev: U32<BigEndian>,
     /// optional, must be zero if unused
     _custom: [U32<BigEndian>; 4],
 }

 lazy_static! {
     static ref IS_VFIO_SUPPORTED: bool =
         Path::new(DEV_VFIO_PATH).exists() && Path::new(VFIO_PLATFORM_DRIVER_PATH).exists();
 }

 fn check_platform_device(path: &Path) -> binder::Result<()> {
     if !path.exists() {
         return Err(anyhow!("no such device {path:?}"))
             .or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT);
     }

     if !path.starts_with(SYSFS_PLATFORM_DEVICES_PATH) {
         return Err(anyhow!("{path:?} is not a platform device"))
             .or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT);
     }

     Ok(())
 }

 fn get_device_iommu_group(path: &Path) -> Option<u64> {
     let group_path = read_link(path.join("iommu_group")).ok()?;
     let group = group_path.file_name()?;
     group.to_str()?.parse().ok()
 }

 fn current_driver(path: &Path) -> Option<String> {
     let driver_path = read_link(path.join("driver")).ok()?;
     let bound_driver = driver_path.file_name()?;
     bound_driver.to_str().map(str::to_string)
 }

 // Try to bind device driver by writing its name to driver_override and triggering driver probe.
 fn try_bind_driver(path: &Path, driver: &str) -> binder::Result<()> {
     if Some(driver) == current_driver(path).as_deref() {
         // already bound
         return Ok(());
     }

     // unbind
     let Some(device) = path.file_name() else {
         return Err(anyhow!("can't get device name from {path:?}"))
             .or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT);
     };
     let Some(device_str) = device.to_str() else {
         return Err(anyhow!("invalid filename {device:?}"))
             .or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT);
     };
     let unbind_path = path.join("driver/unbind");
     if unbind_path.exists() {
         write(&unbind_path, device_str.as_bytes())
             .with_context(|| format!("could not unbind {device_str}"))
             .or_service_specific_exception(-1)?;
     }
     if path.join("driver").exists() {
         return Err(anyhow!("could not unbind {device_str}")).or_service_specific_exception(-1);
     }

     // bind to new driver
     write(path.join("driver_override"), driver.as_bytes())
         .with_context(|| format!("could not bind {device_str} to '{driver}' driver"))
         .or_service_specific_exception(-1)?;

     write(SYSFS_PLATFORM_DRIVERS_PROBE_PATH, device_str.as_bytes())
         .with_context(|| format!("could not write {device_str} to drivers-probe"))
         .or_service_specific_exception(-1)?;

     // final check
     let new_driver = current_driver(path);
     if new_driver.is_none() || Some(driver) != new_driver.as_deref() && driver != DEFAULT_DRIVER {
         return Err(anyhow!("{path:?} still not bound to '{driver}' driver"))
             .or_service_specific_exception(-1);
     }

     Ok(())
 }

 fn bind_device(path: &Path) -> binder::Result<()> {
     let path = path
         .canonicalize()
         .with_context(|| format!("can't canonicalize {path:?}"))
         .or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT)?;

     check_platform_device(&path)?;
     try_bind_driver(&path, VFIO_PLATFORM_DRIVER_NAME)?;

     if get_device_iommu_group(&path).is_none() {
         Err(anyhow!("can't get iommu group for {path:?}")).or_service_specific_exception(-1)
     } else {
         Ok(())
     }
 }

 fn unbind_device(path: &Path) -> binder::Result<()> {
     let path = path
         .canonicalize()
         .with_context(|| format!("can't canonicalize {path:?}"))
         .or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT)?;

     check_platform_device(&path)?;
     try_bind_driver(&path, DEFAULT_DRIVER)?;

     if Some(VFIO_PLATFORM_DRIVER_NAME) == current_driver(&path).as_deref() {
         Err(anyhow!("{path:?} still bound to vfio driver")).or_service_specific_exception(-1)
     } else {
         Ok(())
     }
 }

 fn get_dtbo_img_path() -> binder::Result<PathBuf> {
     let slot_suffix = system_properties::read("ro.boot.slot_suffix")
         .context("Failed to read ro.boot.slot_suffix")
         .or_service_specific_exception(-1)?
         .ok_or_else(|| anyhow!("slot_suffix is none"))
         .or_service_specific_exception(-1)?;
     Ok(PathBuf::from(format!("/dev/block/by-name/dtbo{slot_suffix}")))
 }

 fn read_values(file: &mut File, size: usize, offset: u64) -> binder::Result<Vec<u8>> {
     file.seek(SeekFrom::Start(offset))
         .context("Cannot seek the offset")
         .or_service_specific_exception(-1)?;
     let mut buffer = vec![0_u8; size];
     file.read_exact(&mut buffer)
         .context("Failed to read buffer")
         .or_service_specific_exception(-1)?;
     Ok(buffer)
 }

 fn get_dt_table_header(file: &mut File) -> binder::Result<DtTableHeader> {
     let values = read_values(file, size_of::<DtTableHeader>(), 0)?;
     let dt_table_header = DtTableHeader::read_from(values.as_slice())
         .context("DtTableHeader is invalid")
         .or_service_specific_exception(-1)?;
     if dt_table_header.magic.get() != DT_TABLE_MAGIC
         || dt_table_header.header_size.get() as usize != size_of::<DtTableHeader>()
     {
         return Err(anyhow!("DtTableHeader is invalid")).or_service_specific_exception(-1);
     }
     Ok(dt_table_header)
 }

 fn get_dt_table_entry(
     file: &mut File,
     header: &DtTableHeader,
     index: u32,
 ) -> binder::Result<DtTableEntry> {
     if index >= header.dt_entry_count.get() {
         return Err(anyhow!("Invalid dtbo index {index}")).or_service_specific_exception(-1);
     }
     let Some(prev_dt_entry_total_size) = header.dt_entry_size.get().checked_mul(index) else {
         return Err(anyhow!("Unexpected arithmetic result"))
             .or_binder_exception(ExceptionCode::ILLEGAL_STATE);
     };
     let Some(dt_entry_offset) =
         prev_dt_entry_total_size.checked_add(header.dt_entries_offset.get())
     else {
         return Err(anyhow!("Unexpected arithmetic result"))
             .or_binder_exception(ExceptionCode::ILLEGAL_STATE);
     };
     let values = read_values(file, size_of::<DtTableEntry>(), dt_entry_offset.into())?;
     let dt_table_entry = DtTableEntry::read_from(values.as_slice())
         .with_context(|| format!("DtTableEntry at index {index} is invalid."))
         .or_service_specific_exception(-1)?;
     Ok(dt_table_entry)
 }

 fn write_vm_full_dtbo_from_img(
     dtbo_img_file: &mut File,
     entry: &DtTableEntry,
     dtbo_fd: &ParcelFileDescriptor,
 ) -> binder::Result<()> {
     let dt_size = entry
         .dt_size
         .get()
         .try_into()
         .context("Failed to convert type")
         .or_binder_exception(ExceptionCode::ILLEGAL_STATE)?;
     let buffer = read_values(dtbo_img_file, dt_size, entry.dt_offset.get().into())?;

     let mut dtbo_fd = File::from(
         dtbo_fd
             .as_ref()
             .try_clone()
             .context("Failed to create File from ParcelFileDescriptor")
             .or_binder_exception(ExceptionCode::BAD_PARCELABLE)?,
     );

     dtbo_fd
         .write_all(&buffer)
         .context("Failed to write dtbo file")
         .or_service_specific_exception(-1)?;
     Ok(())
 }
	// Copyright 2023, The Android Open Source Project
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	//! Implementation of the AIDL interface of the VirtualizationService.

	use anyhow::{anyhow, Context};
	use android_system_virtualizationservice_internal::aidl::android::system::virtualizationservice_internal::IBoundDevice::{IBoundDevice, BnBoundDevice};
	use android_system_virtualizationservice_internal::aidl::android::system::virtualizationservice_internal::IVfioHandler::IVfioHandler;
	use android_system_virtualizationservice_internal::aidl::android::system::virtualizationservice_internal::IVfioHandler::VfioDev::VfioDev;
	use android_system_virtualizationservice_internal::binder::ParcelFileDescriptor;
	use binder::{self, BinderFeatures, ExceptionCode, Interface, IntoBinderResult, Strong};
	use lazy_static::lazy_static;
	use log::error;
	use std::fs::{read_link, write, File};
	use std::io::{Read, Seek, SeekFrom, Write};
	use std::mem::size_of;
	use std::path::{Path, PathBuf};
	use rustutils::system_properties;
	use zerocopy::{
	byteorder::{BigEndian, U32},
	FromZeroes,
	FromBytes,
	};

	// Device bound to VFIO driver.
	struct BoundDevice {
	sysfs_path: String,
	dtbo_label: String,
	}

	impl Interface for BoundDevice {}

	impl IBoundDevice for BoundDevice {
	fn getSysfsPath(&self) -> binder::Result<String> {
	Ok(self.sysfs_path.clone())
	}

	fn getDtboLabel(&self) -> binder::Result<String> {
	Ok(self.dtbo_label.clone())
	}
	}

	impl Drop for BoundDevice {
	fn drop(&mut self) {
	unbind_device(Path::new(&self.sysfs_path)).unwrap_or_else(\|e\| {
	error!("did not restore {} driver: {}", self.sysfs_path, e);
	});
	}
	}

	impl BoundDevice {
	fn new_binder(sysfs_path: String, dtbo_label: String) -> Strong<dyn IBoundDevice> {
	BnBoundDevice::new_binder(BoundDevice { sysfs_path, dtbo_label }, BinderFeatures::default())
	}
	}

	#[derive(Debug, Default)]
	pub struct VfioHandler {}

	impl VfioHandler {
	pub fn init() -> VfioHandler {
	VfioHandler::default()
	}
	}

	impl Interface for VfioHandler {}

	impl IVfioHandler for VfioHandler {
	fn bindDevicesToVfioDriver(
	&self,
	devices: &[VfioDev],
	) -> binder::Result<Vec<Strong<dyn IBoundDevice>>> {
	// permission check is already done by IVirtualizationServiceInternal.
	if !*IS_VFIO_SUPPORTED {
	return Err(anyhow!("VFIO-platform not supported"))
	.or_binder_exception(ExceptionCode::UNSUPPORTED_OPERATION);
	}
	devices
	.iter()
	.map(\|d\| {
	bind_device(Path::new(&d.sysfsPath))?;
	Ok(BoundDevice::new_binder(d.sysfsPath.clone(), d.dtboLabel.clone()))
	})
	.collect::<binder::Result<Vec<_>>>()
	}

	fn writeVmDtbo(&self, dtbo_fd: &ParcelFileDescriptor) -> binder::Result<()> {
	let dtbo_path = get_dtbo_img_path()?;
	let mut dtbo_img = File::open(dtbo_path)
	.context("Failed to open DTBO partition")
	.or_service_specific_exception(-1)?;

	let dt_table_header = get_dt_table_header(&mut dtbo_img)?;
	let vm_dtbo_idx = system_properties::read("ro.boot.hypervisor.vm_dtbo_idx")
	.context("Failed to read vm_dtbo_idx")
	.or_service_specific_exception(-1)?
	.ok_or_else(\|\| anyhow!("vm_dtbo_idx is none"))
	.or_service_specific_exception(-1)?;
	let vm_dtbo_idx = vm_dtbo_idx
	.parse()
	.context("vm_dtbo_idx is not an integer")
	.or_service_specific_exception(-1)?;
	let dt_table_entry = get_dt_table_entry(&mut dtbo_img, &dt_table_header, vm_dtbo_idx)?;
	write_vm_full_dtbo_from_img(&mut dtbo_img, &dt_table_entry, dtbo_fd)?;
	Ok(())
	}
	}

	const DEV_VFIO_PATH: &str = "/dev/vfio/vfio";
	const SYSFS_PLATFORM_DEVICES_PATH: &str = "/sys/devices/platform/";
	const VFIO_PLATFORM_DRIVER_PATH: &str = "/sys/bus/platform/drivers/vfio-platform";
	const SYSFS_PLATFORM_DRIVERS_PROBE_PATH: &str = "/sys/bus/platform/drivers_probe";
	const DT_TABLE_MAGIC: u32 = 0xd7b7ab1e;
	const VFIO_PLATFORM_DRIVER_NAME: &str = "vfio-platform";
	// To remove the override and match the device driver by "compatible" string again,
	// driver_override file must be cleared. Writing an empty string (same as
	// `echo -n "" > driver_override`) won't' clear the file, so append a newline char.
	const DEFAULT_DRIVER: &str = "\n";

	/// The structure of DT table header in dtbo.img.
	/// https://source.android.com/docs/core/architecture/dto/partitions
	#[repr(C)]
	#[derive(Debug, FromZeroes, FromBytes)]
	struct DtTableHeader {
	/// DT_TABLE_MAGIC
	magic: U32<BigEndian>,
	/// includes dt_table_header + all dt_table_entry and all dtb/dtbo
	_total_size: U32<BigEndian>,
	/// sizeof(dt_table_header)
	header_size: U32<BigEndian>,
	/// sizeof(dt_table_entry)
	dt_entry_size: U32<BigEndian>,
	/// number of dt_table_entry
	dt_entry_count: U32<BigEndian>,
	/// offset to the first dt_table_entry from head of dt_table_header
	dt_entries_offset: U32<BigEndian>,
	/// flash page size we assume
	_page_size: U32<BigEndian>,
	/// DTBO image version, the current version is 0. The version will be
	/// incremented when the dt_table_header struct is updated.
	_version: U32<BigEndian>,
	}

	/// The structure of each DT table entry (v0) in dtbo.img.
	/// https://source.android.com/docs/core/architecture/dto/partitions
	#[repr(C)]
	#[derive(Debug, FromZeroes, FromBytes)]
	struct DtTableEntry {
	/// size of each DT
	dt_size: U32<BigEndian>,
	/// offset from head of dt_table_header
	dt_offset: U32<BigEndian>,
	/// optional, must be zero if unused
	_id: U32<BigEndian>,
	/// optional, must be zero if unused
	_rev: U32<BigEndian>,
	/// optional, must be zero if unused
	_custom: [U32<BigEndian>; 4],
	}

	lazy_static! {
	static ref IS_VFIO_SUPPORTED: bool =
	Path::new(DEV_VFIO_PATH).exists() && Path::new(VFIO_PLATFORM_DRIVER_PATH).exists();
	}

	fn check_platform_device(path: &Path) -> binder::Result<()> {
	if !path.exists() {
	return Err(anyhow!("no such device {path:?}"))
	.or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT);
	}

	if !path.starts_with(SYSFS_PLATFORM_DEVICES_PATH) {
	return Err(anyhow!("{path:?} is not a platform device"))
	.or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT);
	}

	Ok(())
	}

	fn get_device_iommu_group(path: &Path) -> Option<u64> {
	let group_path = read_link(path.join("iommu_group")).ok()?;
	let group = group_path.file_name()?;
	group.to_str()?.parse().ok()
	}

	fn current_driver(path: &Path) -> Option<String> {
	let driver_path = read_link(path.join("driver")).ok()?;
	let bound_driver = driver_path.file_name()?;
	bound_driver.to_str().map(str::to_string)
	}

	// Try to bind device driver by writing its name to driver_override and triggering driver probe.
	fn try_bind_driver(path: &Path, driver: &str) -> binder::Result<()> {
	if Some(driver) == current_driver(path).as_deref() {
	// already bound
	return Ok(());
	}

	// unbind
	let Some(device) = path.file_name() else {
	return Err(anyhow!("can't get device name from {path:?}"))
	.or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT);
	};
	let Some(device_str) = device.to_str() else {
	return Err(anyhow!("invalid filename {device:?}"))
	.or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT);
	};
	let unbind_path = path.join("driver/unbind");
	if unbind_path.exists() {
	write(&unbind_path, device_str.as_bytes())
	.with_context(\|\| format!("could not unbind {device_str}"))
	.or_service_specific_exception(-1)?;
	}
	if path.join("driver").exists() {
	return Err(anyhow!("could not unbind {device_str}")).or_service_specific_exception(-1);
	}

	// bind to new driver
	write(path.join("driver_override"), driver.as_bytes())
	.with_context(\|\| format!("could not bind {device_str} to '{driver}' driver"))
	.or_service_specific_exception(-1)?;

	write(SYSFS_PLATFORM_DRIVERS_PROBE_PATH, device_str.as_bytes())
	.with_context(\|\| format!("could not write {device_str} to drivers-probe"))
	.or_service_specific_exception(-1)?;

	// final check
	let new_driver = current_driver(path);
	if new_driver.is_none() \|\| Some(driver) != new_driver.as_deref() && driver != DEFAULT_DRIVER {
	return Err(anyhow!("{path:?} still not bound to '{driver}' driver"))
	.or_service_specific_exception(-1);
	}

	Ok(())
	}

	fn bind_device(path: &Path) -> binder::Result<()> {
	let path = path
	.canonicalize()
	.with_context(\|\| format!("can't canonicalize {path:?}"))
	.or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT)?;

	check_platform_device(&path)?;
	try_bind_driver(&path, VFIO_PLATFORM_DRIVER_NAME)?;

	if get_device_iommu_group(&path).is_none() {
	Err(anyhow!("can't get iommu group for {path:?}")).or_service_specific_exception(-1)
	} else {
	Ok(())
	}
	}

	fn unbind_device(path: &Path) -> binder::Result<()> {
	let path = path
	.canonicalize()
	.with_context(\|\| format!("can't canonicalize {path:?}"))
	.or_binder_exception(ExceptionCode::ILLEGAL_ARGUMENT)?;

	check_platform_device(&path)?;
	try_bind_driver(&path, DEFAULT_DRIVER)?;

	if Some(VFIO_PLATFORM_DRIVER_NAME) == current_driver(&path).as_deref() {
	Err(anyhow!("{path:?} still bound to vfio driver")).or_service_specific_exception(-1)
	} else {
	Ok(())
	}
	}

	fn get_dtbo_img_path() -> binder::Result<PathBuf> {
	let slot_suffix = system_properties::read("ro.boot.slot_suffix")
	.context("Failed to read ro.boot.slot_suffix")
	.or_service_specific_exception(-1)?
	.ok_or_else(\|\| anyhow!("slot_suffix is none"))
	.or_service_specific_exception(-1)?;
	Ok(PathBuf::from(format!("/dev/block/by-name/dtbo{slot_suffix}")))
	}

	fn read_values(file: &mut File, size: usize, offset: u64) -> binder::Result<Vec<u8>> {
	file.seek(SeekFrom::Start(offset))
	.context("Cannot seek the offset")
	.or_service_specific_exception(-1)?;
	let mut buffer = vec![0_u8; size];
	file.read_exact(&mut buffer)
	.context("Failed to read buffer")
	.or_service_specific_exception(-1)?;
	Ok(buffer)
	}

	fn get_dt_table_header(file: &mut File) -> binder::Result<DtTableHeader> {
	let values = read_values(file, size_of::<DtTableHeader>(), 0)?;
	let dt_table_header = DtTableHeader::read_from(values.as_slice())
	.context("DtTableHeader is invalid")
	.or_service_specific_exception(-1)?;
	if dt_table_header.magic.get() != DT_TABLE_MAGIC
	\|\| dt_table_header.header_size.get() as usize != size_of::<DtTableHeader>()
	{
	return Err(anyhow!("DtTableHeader is invalid")).or_service_specific_exception(-1);
	}
	Ok(dt_table_header)
	}

	fn get_dt_table_entry(
	file: &mut File,
	header: &DtTableHeader,
	index: u32,
	) -> binder::Result<DtTableEntry> {
	if index >= header.dt_entry_count.get() {
	return Err(anyhow!("Invalid dtbo index {index}")).or_service_specific_exception(-1);
	}
	let Some(prev_dt_entry_total_size) = header.dt_entry_size.get().checked_mul(index) else {
	return Err(anyhow!("Unexpected arithmetic result"))
	.or_binder_exception(ExceptionCode::ILLEGAL_STATE);
	};
	let Some(dt_entry_offset) =
	prev_dt_entry_total_size.checked_add(header.dt_entries_offset.get())
	else {
	return Err(anyhow!("Unexpected arithmetic result"))
	.or_binder_exception(ExceptionCode::ILLEGAL_STATE);
	};
	let values = read_values(file, size_of::<DtTableEntry>(), dt_entry_offset.into())?;
	let dt_table_entry = DtTableEntry::read_from(values.as_slice())
	.with_context(\|\| format!("DtTableEntry at index {index} is invalid."))
	.or_service_specific_exception(-1)?;
	Ok(dt_table_entry)
	}

	fn write_vm_full_dtbo_from_img(
	dtbo_img_file: &mut File,
	entry: &DtTableEntry,
	dtbo_fd: &ParcelFileDescriptor,
	) -> binder::Result<()> {
	let dt_size = entry
	.dt_size
	.get()
	.try_into()
	.context("Failed to convert type")
	.or_binder_exception(ExceptionCode::ILLEGAL_STATE)?;
	let buffer = read_values(dtbo_img_file, dt_size, entry.dt_offset.get().into())?;

	let mut dtbo_fd = File::from(
	dtbo_fd
	.as_ref()
	.try_clone()
	.context("Failed to create File from ParcelFileDescriptor")
	.or_binder_exception(ExceptionCode::BAD_PARCELABLE)?,
	);

	dtbo_fd
	.write_all(&buffer)
	.context("Failed to write dtbo file")
	.or_service_specific_exception(-1)?;
	Ok(())
	}