implement memory allocation in boot setup

xencall/src/memory.rs

@@ -0,0 +1,40 @@
+use crate::sys::{MemoryReservation, HYPERVISOR_MEMORY_OP, XEN_MEM_POPULATE_PHYSMAP};
+use crate::{XenCall, XenCallError};
+
+use std::ffi::c_ulong;
+
+use std::ptr::addr_of;
+
+pub struct MemoryControl<'a> {
+    call: &'a XenCall,
+}
+
+impl MemoryControl<'_> {
+    pub fn new(call: &XenCall) -> MemoryControl {
+        MemoryControl { call }
+    }
+
+    pub fn populate_physmap(
+        &self,
+        domid: u32,
+        nr_extents: u64,
+        extent_order: u32,
+        mem_flags: u32,
+        extent_starts: &[u64],
+    ) -> Result<Vec<u64>, XenCallError> {
+        let extent_starts = extent_starts.to_vec();
+        let reservation = MemoryReservation {
+            extent_start: addr_of!(extent_starts) as c_ulong,
+            nr_extents,
+            extent_order,
+            mem_flags,
+            domid: domid as u16,
+        };
+        self.call.hypercall2(
+            HYPERVISOR_MEMORY_OP,
+            XEN_MEM_POPULATE_PHYSMAP as c_ulong,
+            addr_of!(reservation) as c_ulong,
+        )?;
+        Ok(extent_starts)
+    }
+}