we've done it, it boots!

xenclient/src/mem.rs

@@ -1,4 +1,4 @@
-use crate::sys::XEN_PAGE_SHIFT;
+use crate::sys::{XEN_PAGE_SHIFT, XEN_PAGE_SIZE};
 use crate::XenClientError;
 use libc::munmap;
 use log::debug;
@@ -114,6 +114,36 @@ impl PhysicalPages<'_> {
         Ok(addr)
     }
 
+    pub fn map_foreign_pages(&mut self, mfn: u64, size: u64) -> Result<u64, XenClientError> {
+        let num = ((size + XEN_PAGE_SIZE - 1) >> XEN_PAGE_SHIFT) as usize;
+        let mut pfns = vec![u64::MAX; num];
+        for (i, item) in pfns.iter_mut().enumerate().take(num) {
+            *item = mfn + i as u64;
+        }
+
+        let actual_mmap_len = (num as u64) << XEN_PAGE_SHIFT;
+        let addr = self
+            .call
+            .mmap(0, actual_mmap_len)
+            .ok_or(XenClientError::new("failed to mmap address"))?;
+        debug!("mapped {:#x} foreign bytes at {:#x}", actual_mmap_len, addr);
+        let result = self.call.mmap_batch(self.domid, num as u64, addr, pfns)?;
+        if result != 0 {
+            return Err(XenClientError::new("mmap_batch call failed"));
+        }
+        let page = PhysicalPage {
+            pfn: u64::MAX,
+            ptr: addr,
+            count: num as u64,
+        };
+        debug!(
+            "alloc_mfn {:#x}+{:#x} at {:#x}",
+            page.pfn, page.count, page.ptr
+        );
+        self.pages.push(page);
+        Ok(addr)
+    }
+
     pub fn unmap_all(&mut self) -> Result<(), XenClientError> {
         for page in &self.pages {
             unsafe {
@@ -131,11 +161,11 @@ impl PhysicalPages<'_> {
     }
 
     pub fn unmap(&mut self, pfn: u64) -> Result<(), XenClientError> {
-        let page = self.pages.iter().find(|x| x.pfn == pfn);
+        let page = self.pages.iter().enumerate().find(|(_, x)| x.pfn == pfn);
         if page.is_none() {
             return Err(XenClientError::new("unable to find page to unmap"));
         }
-        let page = page.unwrap();
+        let (i, page) = page.unwrap();
 
         unsafe {
             let err = munmap(
@@ -150,6 +180,7 @@ impl PhysicalPages<'_> {
             if err != 0 {
                 return Err(XenClientError::new("failed to munmap page"));
             }
+            self.pages.remove(i);
         }
         Ok(())
     }