vm-allocator: Enable vm-allocator for AArch64

Implemented GSI allocator and system allocator for AArch64.
Renamed some layout definitions to align more code between architectures.

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

vm-allocator/src/gsi.rs

@@ -2,6 +2,9 @@
 //
 // SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
 
+#[cfg(target_arch = "aarch64")]
+use arch;
+#[cfg(target_arch = "x86_64")]
 use std::collections::btree_map::BTreeMap;
 use std::result;
 
@@ -13,12 +16,14 @@ pub enum Error {
 pub type Result<T> = result::Result<T, Error>;
 
 /// GsiApic
+#[cfg(target_arch = "x86_64")]
 #[derive(Copy, Clone)]
 pub struct GsiApic {
     base: u32,
     irqs: u32,
 }
 
+#[cfg(target_arch = "x86_64")]
 impl GsiApic {
     /// New GSI APIC
     pub fn new(base: u32, irqs: u32) -> Self {
@@ -28,12 +33,14 @@ impl GsiApic {
 
 /// GsiAllocator
 pub struct GsiAllocator {
+    #[cfg(target_arch = "x86_64")]
     apics: BTreeMap<u32, u32>,
     next_irq: u32,
     next_gsi: u32,
 }
 
 impl GsiAllocator {
+    #[cfg(target_arch = "x86_64")]
     /// New GSI allocator
     pub fn new(apics: Vec<GsiApic>) -> Self {
         let mut allocator = GsiAllocator {
@@ -57,13 +64,23 @@ impl GsiAllocator {
         allocator
     }
 
-    /// Allocate a GSI
-    pub fn allocate_gsi(&mut self) -> Result<u32> {
-        self.next_gsi = self.next_gsi.checked_add(1).ok_or(Error::Overflow)?;
-
-        Ok(self.next_gsi - 1)
+    #[cfg(target_arch = "aarch64")]
+    /// New GSI allocator
+    pub fn new() -> Self {
+        GsiAllocator {
+            next_irq: arch::IRQ_BASE,
+            next_gsi: arch::IRQ_BASE,
+        }
     }
 
+    /// Allocate a GSI
+    pub fn allocate_gsi(&mut self) -> Result<u32> {
+        let gsi = self.next_gsi;
+        self.next_gsi = self.next_gsi.checked_add(1).ok_or(Error::Overflow)?;
+        Ok(gsi)
+    }
+
+    #[cfg(target_arch = "x86_64")]
     /// Allocate an IRQ
     pub fn allocate_irq(&mut self) -> Result<u32> {
         let mut irq: u32 = 0;
@@ -81,4 +98,12 @@ impl GsiAllocator {
 
         Ok(irq)
     }
+
+    #[cfg(target_arch = "aarch64")]
+    /// Allocate an IRQ
+    pub fn allocate_irq(&mut self) -> Result<u32> {
+        let irq = self.next_irq;
+        self.next_irq = self.next_irq.checked_add(1).ok_or(Error::Overflow)?;
+        Ok(irq)
+    }
 }