misc: Adapt consistent import style formatting

Historically the Cloud Hypervisor coding style has been to ensure that
all imports are ordered and placed in a single group. Unfortunately
cargo fmt has no support for ensuring that all imports are in a single
group so if whitespace lines were added as part of the import statements
then they would only be odered correctly in the group.

By adopting "group_imports="StdExternalCrate" we can enforce a style
where imports are placed in at most three groups for std, external
crates and the crate itself. Choosing a style enforceable by the tooling
reduces the reviewer burden.

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>

pci/src/bus.rs

@@ -4,17 +4,19 @@
 //
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 
+use std::any::Any;
+use std::collections::HashMap;
+use std::ops::DerefMut;
+use std::sync::{Arc, Barrier, Mutex};
+
+use byteorder::{ByteOrder, LittleEndian};
+use vm_device::{Bus, BusDevice, BusDeviceSync};
+
 use crate::configuration::{
     PciBarRegionType, PciBridgeSubclass, PciClassCode, PciConfiguration, PciHeaderType,
 };
 use crate::device::{DeviceRelocation, Error as PciDeviceError, PciDevice};
 use crate::PciBarConfiguration;
-use byteorder::{ByteOrder, LittleEndian};
-use std::any::Any;
-use std::collections::HashMap;
-use std::ops::DerefMut;
-use std::sync::{Arc, Barrier, Mutex};
-use vm_device::{Bus, BusDevice, BusDeviceSync};
 
 const VENDOR_ID_INTEL: u16 = 0x8086;
 const DEVICE_ID_INTEL_VIRT_PCIE_HOST: u16 = 0x0d57;

pci/src/configuration.rs

@@ -4,15 +4,17 @@
 //
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 
-use crate::device::BarReprogrammingParams;
-use crate::{MsixConfig, PciInterruptPin};
-use byteorder::{ByteOrder, LittleEndian};
-use serde::{Deserialize, Serialize};
 use std::fmt::{self, Display};
 use std::sync::{Arc, Mutex};
+
+use byteorder::{ByteOrder, LittleEndian};
+use serde::{Deserialize, Serialize};
 use vm_device::PciBarType;
 use vm_migration::{MigratableError, Pausable, Snapshot, Snapshottable};
 
+use crate::device::BarReprogrammingParams;
+use crate::{MsixConfig, PciInterruptPin};
+
 // The number of 32bit registers in the config space, 4096 bytes.
 const NUM_CONFIGURATION_REGISTERS: usize = 1024;
 

pci/src/device.rs

@@ -4,15 +4,17 @@
 //
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 
-use crate::configuration::{self, PciBarRegionType};
-use crate::PciBarConfiguration;
 use std::any::Any;
 use std::fmt::{self, Display};
 use std::sync::{Arc, Barrier, Mutex};
 use std::{io, result};
+
 use vm_allocator::{AddressAllocator, SystemAllocator};
 use vm_device::Resource;
 
+use crate::configuration::{self, PciBarRegionType};
+use crate::PciBarConfiguration;
+
 #[derive(Debug)]
 pub enum Error {
     /// Setup of the device capabilities failed.

pci/src/lib.rs

@@ -16,6 +16,12 @@ mod msix;
 mod vfio;
 mod vfio_user;
 
+use std::fmt::{self, Display};
+use std::num::ParseIntError;
+use std::str::FromStr;
+
+use serde::de::Visitor;
+
 pub use self::bus::{PciBus, PciConfigIo, PciConfigMmio, PciRoot, PciRootError};
 pub use self::configuration::{
     PciBarConfiguration, PciBarPrefetchable, PciBarRegionType, PciCapability, PciCapabilityId,
@@ -30,10 +36,6 @@ pub use self::msi::{msi_num_enabled_vectors, MsiCap, MsiConfig};
 pub use self::msix::{MsixCap, MsixConfig, MsixTableEntry, MSIX_CONFIG_ID, MSIX_TABLE_ENTRY_SIZE};
 pub use self::vfio::{MmioRegion, VfioDmaMapping, VfioPciDevice, VfioPciError};
 pub use self::vfio_user::{VfioUserDmaMapping, VfioUserPciDevice, VfioUserPciDeviceError};
-use serde::de::Visitor;
-use std::fmt::{self, Display};
-use std::num::ParseIntError;
-use std::str::FromStr;
 
 /// PCI has four interrupt pins A->D.
 #[derive(Copy, Clone)]

pci/src/msi.rs

@@ -3,10 +3,11 @@
 // SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
 //
 
-use byteorder::{ByteOrder, LittleEndian};
-use serde::{Deserialize, Serialize};
 use std::io;
 use std::sync::Arc;
+
+use byteorder::{ByteOrder, LittleEndian};
+use serde::{Deserialize, Serialize};
 use thiserror::Error;
 use vm_device::interrupt::{
     InterruptIndex, InterruptSourceConfig, InterruptSourceGroup, MsiIrqSourceConfig,

pci/src/msix.rs

@@ -3,19 +3,21 @@
 // SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
 //
 
-use crate::{PciCapability, PciCapabilityId};
-use byteorder::{ByteOrder, LittleEndian};
-use serde::Deserialize;
-use serde::Serialize;
 use std::io;
 use std::result;
 use std::sync::Arc;
+
+use byteorder::{ByteOrder, LittleEndian};
+use serde::Deserialize;
+use serde::Serialize;
 use vm_device::interrupt::{
     InterruptIndex, InterruptSourceConfig, InterruptSourceGroup, MsiIrqSourceConfig,
 };
 use vm_memory::ByteValued;
 use vm_migration::{MigratableError, Pausable, Snapshot, Snapshottable};
 
+use crate::{PciCapability, PciCapabilityId};
+
 const MAX_MSIX_VECTORS_PER_DEVICE: u16 = 2048;
 const MSIX_TABLE_ENTRIES_MODULO: u64 = 16;
 const MSIX_PBA_ENTRIES_MODULO: u64 = 8;

pci/src/vfio.rs

@@ -3,25 +3,18 @@
 // SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
 //
 
-use crate::msi::{MsiConfigState, MSI_CONFIG_ID};
-use crate::msix::MsixConfigState;
-use crate::{
-    msi_num_enabled_vectors, BarReprogrammingParams, MsiCap, MsiConfig, MsixCap, MsixConfig,
-    PciBarConfiguration, PciBarPrefetchable, PciBarRegionType, PciBdf, PciCapabilityId,
-    PciClassCode, PciConfiguration, PciDevice, PciDeviceError, PciExpressCapabilityId,
-    PciHeaderType, PciSubclass, MSIX_CONFIG_ID, MSIX_TABLE_ENTRY_SIZE, PCI_CONFIGURATION_ID,
-};
-use anyhow::anyhow;
-use byteorder::{ByteOrder, LittleEndian};
-use hypervisor::HypervisorVmError;
-use libc::{sysconf, _SC_PAGESIZE};
-use serde::{Deserialize, Serialize};
 use std::any::Any;
 use std::collections::{BTreeMap, HashMap};
 use std::io;
 use std::os::unix::io::AsRawFd;
 use std::ptr::null_mut;
 use std::sync::{Arc, Barrier, Mutex};
+
+use anyhow::anyhow;
+use byteorder::{ByteOrder, LittleEndian};
+use hypervisor::HypervisorVmError;
+use libc::{sysconf, _SC_PAGESIZE};
+use serde::{Deserialize, Serialize};
 use thiserror::Error;
 use vfio_bindings::bindings::vfio::*;
 use vfio_ioctls::{
@@ -40,6 +33,15 @@ use vm_memory::{Address, GuestAddress, GuestAddressSpace, GuestMemory, GuestUsiz
 use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};
 use vmm_sys_util::eventfd::EventFd;
 
+use crate::msi::{MsiConfigState, MSI_CONFIG_ID};
+use crate::msix::MsixConfigState;
+use crate::{
+    msi_num_enabled_vectors, BarReprogrammingParams, MsiCap, MsiConfig, MsixCap, MsixConfig,
+    PciBarConfiguration, PciBarPrefetchable, PciBarRegionType, PciBdf, PciCapabilityId,
+    PciClassCode, PciConfiguration, PciDevice, PciDeviceError, PciExpressCapabilityId,
+    PciHeaderType, PciSubclass, MSIX_CONFIG_ID, MSIX_TABLE_ENTRY_SIZE, PCI_CONFIGURATION_ID,
+};
+
 pub(crate) const VFIO_COMMON_ID: &str = "vfio_common";
 
 #[derive(Debug, Error)]

pci/src/vfio_user.rs

@@ -3,14 +3,12 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
-use crate::vfio::{UserMemoryRegion, Vfio, VfioCommon, VfioError, VFIO_COMMON_ID};
-use crate::{BarReprogrammingParams, PciBarConfiguration, VfioPciError};
-use crate::{PciBdf, PciDevice, PciDeviceError, PciSubclass};
-use hypervisor::HypervisorVmError;
 use std::any::Any;
 use std::os::unix::prelude::AsRawFd;
 use std::ptr::null_mut;
 use std::sync::{Arc, Barrier, Mutex};
+
+use hypervisor::HypervisorVmError;
 use thiserror::Error;
 use vfio_bindings::bindings::vfio::*;
 use vfio_ioctls::VfioIrq;
@@ -26,6 +24,10 @@ use vm_memory::{
 use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};
 use vmm_sys_util::eventfd::EventFd;
 
+use crate::vfio::{UserMemoryRegion, Vfio, VfioCommon, VfioError, VFIO_COMMON_ID};
+use crate::{BarReprogrammingParams, PciBarConfiguration, VfioPciError};
+use crate::{PciBdf, PciDevice, PciDeviceError, PciSubclass};
+
 pub struct VfioUserPciDevice {
     id: String,
     vm: Arc<dyn hypervisor::Vm>,