build: Fixed build errors and warnings on AArch64

This is a preparing commit to build and test CH on AArch64. All building
issues were fixed, but no functionality was introduced.
For X86, the logic of code was not changed at all.
For ARM, the architecture specific part is still empty. And we applied
some tricks to workaround lint warnings. But such code will be replaced
later by other commits with real functionality.

Signed-off-by: Michael Zhao <michael.zhao@arm.com>

vmm/src/vm.rs

@@ -35,24 +35,37 @@ use crate::memory_manager::{Error as MemoryManagerError, MemoryManager};
 use crate::migration::{url_to_path, vm_config_from_snapshot, VM_SNAPSHOT_FILE};
 use crate::{CPU_MANAGER_SNAPSHOT_ID, DEVICE_MANAGER_SNAPSHOT_ID, MEMORY_MANAGER_SNAPSHOT_ID};
 use anyhow::anyhow;
-use arch::{BootProtocol, EntryPoint};
-use devices::{ioapic, HotPlugNotificationFlags};
+#[cfg(target_arch = "x86_64")]
+use arch::BootProtocol;
+use arch::{check_required_kvm_extensions, EntryPoint};
+#[cfg(target_arch = "x86_64")]
+use devices::ioapic;
+use devices::HotPlugNotificationFlags;
+#[cfg(target_arch = "x86_64")]
 use kvm_bindings::{kvm_enable_cap, kvm_userspace_memory_region, KVM_CAP_SPLIT_IRQCHIP};
 use kvm_ioctls::*;
+#[cfg(target_arch = "x86_64")]
 use linux_loader::cmdline::Cmdline;
+#[cfg(target_arch = "x86_64")]
 use linux_loader::loader::elf::Error::InvalidElfMagicNumber;
+#[cfg(target_arch = "x86_64")]
 use linux_loader::loader::KernelLoader;
 use signal_hook::{iterator::Signals, SIGINT, SIGTERM, SIGWINCH};
+#[cfg(target_arch = "x86_64")]
 use std::convert::TryInto;
+#[cfg(target_arch = "x86_64")]
 use std::ffi::CString;
 use std::fs::{File, OpenOptions};
-use std::io::Write;
-use std::io::{self, Seek, SeekFrom};
+use std::io::{self, Write};
+#[cfg(target_arch = "x86_64")]
+use std::io::{Seek, SeekFrom};
+#[cfg(target_arch = "x86_64")]
 use std::ops::Deref;
 use std::path::PathBuf;
 use std::sync::{Arc, Mutex, RwLock};
 use std::{result, str, thread};
 use url::Url;
+#[cfg(target_arch = "x86_64")]
 use vm_memory::{
     Address, Bytes, GuestAddress, GuestAddressSpace, GuestMemory, GuestMemoryMmap,
     GuestMemoryRegion,
@@ -65,6 +78,7 @@ use vmm_sys_util::eventfd::EventFd;
 use vmm_sys_util::terminal::Terminal;
 
 // 64 bit direct boot entry offset for bzImage
+#[cfg(target_arch = "x86_64")]
 const KERNEL_64BIT_ENTRY_OFFSET: u64 = 0x200;
 
 /// Errors associated with VM management
@@ -153,9 +167,6 @@ pub enum Error {
     /// Error from CPU handling
     CpuManager(cpu::Error),
 
-    /// Capability missing
-    CapabilityMissing(Cap),
-
     /// Cannot pause devices
     PauseDevices(MigratableError),
 
@@ -246,7 +257,9 @@ impl VmState {
 }
 
 pub struct Vm {
+    #[cfg_attr(target_arch = "aarch64", allow(dead_code))]
     kernel: File,
+    #[cfg_attr(target_arch = "aarch64", allow(dead_code))]
     initramfs: Option<File>,
     threads: Vec<thread::JoinHandle<()>>,
     device_manager: Arc<Mutex<DeviceManager>>,
@@ -262,18 +275,7 @@ impl Vm {
     fn kvm_new() -> Result<(Kvm, Arc<VmFd>)> {
         let kvm = Kvm::new().map_err(Error::KvmNew)?;
 
-        // Check required capabilities:
-        if !kvm.check_extension(Cap::SignalMsi) {
-            return Err(Error::CapabilityMissing(Cap::SignalMsi));
-        }
-
-        if !kvm.check_extension(Cap::TscDeadlineTimer) {
-            return Err(Error::CapabilityMissing(Cap::TscDeadlineTimer));
-        }
-
-        if !kvm.check_extension(Cap::SplitIrqchip) {
-            return Err(Error::CapabilityMissing(Cap::SplitIrqchip));
-        }
+        check_required_kvm_extensions(&kvm).expect("Missing KVM capabilities");
 
         let fd: VmFd;
         loop {
@@ -295,16 +297,20 @@ impl Vm {
         let fd = Arc::new(fd);
 
         // Set TSS
+        #[cfg(target_arch = "x86_64")]
         fd.set_tss_address(arch::x86_64::layout::KVM_TSS_ADDRESS.raw_value() as usize)
             .map_err(Error::VmSetup)?;
 
-        // Create split irqchip
-        // Only the local APIC is emulated in kernel, both PICs and IOAPIC
-        // are not.
-        let mut cap: kvm_enable_cap = Default::default();
-        cap.cap = KVM_CAP_SPLIT_IRQCHIP;
-        cap.args[0] = ioapic::NUM_IOAPIC_PINS as u64;
-        fd.enable_cap(&cap).map_err(Error::VmSetup)?;
+        #[cfg(target_arch = "x86_64")]
+        {
+            // Create split irqchip
+            // Only the local APIC is emulated in kernel, both PICs and IOAPIC
+            // are not.
+            let mut cap: kvm_enable_cap = Default::default();
+            cap.cap = KVM_CAP_SPLIT_IRQCHIP;
+            cap.args[0] = ioapic::NUM_IOAPIC_PINS as u64;
+            fd.enable_cap(&cap).map_err(Error::VmSetup)?;
+        }
 
         Ok((kvm, fd))
     }
@@ -446,6 +452,7 @@ impl Vm {
         )
     }
 
+    #[cfg(target_arch = "x86_64")]
     fn load_initramfs(&mut self, guest_mem: &GuestMemoryMmap) -> Result<arch::InitramfsConfig> {
         let mut initramfs = self.initramfs.as_ref().unwrap();
         let size: usize = initramfs
@@ -468,6 +475,12 @@ impl Vm {
         Ok(arch::InitramfsConfig { address, size })
     }
 
+    #[cfg(target_arch = "aarch64")]
+    fn load_kernel(&mut self) -> Result<EntryPoint> {
+        unimplemented!();
+    }
+
+    #[cfg(target_arch = "x86_64")]
     fn load_kernel(&mut self) -> Result<EntryPoint> {
         let mut cmdline = Cmdline::new(arch::CMDLINE_MAX_SIZE);
         cmdline
@@ -1276,6 +1289,7 @@ impl Transportable for Vm {
 }
 impl Migratable for Vm {}
 
+#[cfg(target_arch = "x86_64")]
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1334,6 +1348,7 @@ mod tests {
     }
 }
 
+#[cfg(target_arch = "x86_64")]
 #[allow(unused)]
 pub fn test_vm() {
     // This example based on https://lwn.net/Articles/658511/