Make mmap_unix.rs and mmap_xen.rs not mutually exclusive

Now that all tension between these two modules is resolves (e.g. no more
code depends on exactly one of these being defined, and tests can
support iterating over multiple supported backends), drop all the
`cfg(not(feature = "xen"))` from across the code base.

Signed-off-by: Patrick Roy <roypat@amazon.co.uk>

Author: roypat

CHANGELOG.md

@@ -16,6 +16,9 @@
   based on linear search.
 - \[[#312](https://github.com/rust-vmm/vm-memory/pull/312)\]: Implement `Bytes<MemoryRegionAddress>` generically
   for all `R: GuestMemoryRegion`.
+- \[[#317](https://github.com/rust-vmm/vm-memory/pull/317)\]: Make `xen` feature additive, meaning enabling it
+  no longer disables the `mmap_unix` module at compile time. For this, various Xen-related structs had to be
+  renamed due to naming conflicts.
 
 ### Removed
 

src/bytes.rs

@@ -330,7 +330,7 @@ pub trait Bytes<A> {
     /// * Read bytes from /dev/urandom (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", feature = "rawfd", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", feature = "rawfd", unix))]
     /// # {
     /// # use vm_memory::{Address, GuestMemory, Bytes, GuestAddress, GuestMemoryMmap};
     /// # use std::fs::File;

src/guest_memory.rs

@@ -174,7 +174,7 @@ impl FileOffset {
 /// # Examples (uses the `backend-mmap` and `backend-atomic` features)
 ///
 /// ```
-/// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+/// # #[cfg(all(feature = "backend-mmap", unix))]
 /// # {
 /// # use std::sync::Arc;
 /// # use vm_memory::{GuestAddress, GuestAddressSpace, GuestMemory, GuestMemoryMmap};
@@ -290,7 +290,7 @@ pub trait GuestMemory {
     ///   `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
     /// # use vm_memory::{GuestAddress, GuestMemory, GuestMemoryRegion, GuestMemoryMmap};
     /// #
@@ -314,7 +314,7 @@ pub trait GuestMemory {
     /// # Examples (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
     /// # use vm_memory::{Address, GuestAddress, GuestMemory, GuestMemoryMmap};
     /// #
@@ -426,7 +426,7 @@ pub trait GuestMemory {
     /// # Examples (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
     /// # use vm_memory::{GuestAddress, GuestMemory, GuestMemoryMmap};
     /// #
@@ -483,9 +483,9 @@ impl<T: GuestMemory + ?Sized> Bytes<GuestAddress> for T {
     /// * Write a slice at guestaddress 0x1000. (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
-    /// # use vm_memory::{Bytes, GuestAddress, mmap::GuestMemoryMmap};
+    /// # use vm_memory::{Bytes, GuestAddress, GuestMemoryMmap};
     /// #
     /// # let start_addr = GuestAddress(0x1000);
     /// # let mut gm = GuestMemoryMmap::<()>::from_ranges(&vec![(start_addr, 0x400)])
@@ -511,9 +511,9 @@ impl<T: GuestMemory + ?Sized> Bytes<GuestAddress> for T {
     /// * Read a slice of length 16 at guestaddress 0x1000. (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
-    /// # use vm_memory::{Bytes, GuestAddress, mmap::GuestMemoryMmap};
+    /// # use vm_memory::{Bytes, GuestAddress, GuestMemoryMmap};
     /// #
     /// let start_addr = GuestAddress(0x1000);
     /// let mut gm = GuestMemoryMmap::<()>::from_ranges(&vec![(start_addr, 0x400)])

src/lib.rs

@@ -56,7 +56,7 @@ pub use region::{GuestMemoryRegion, GuestRegionCollection, GuestRegionError as E
 pub mod io;
 pub use io::{ReadVolatile, WriteVolatile};
 
-#[cfg(all(feature = "backend-mmap", not(feature = "xen"), unix))]
+#[cfg(all(feature = "backend-mmap", unix))]
 mod mmap_unix;
 
 #[cfg(all(feature = "backend-mmap", feature = "xen", unix))]
@@ -68,14 +68,13 @@ mod mmap_windows;
 #[cfg(feature = "backend-mmap")]
 pub mod mmap;
 
-#[cfg(all(feature = "backend-mmap", feature = "xen", unix))]
-pub use mmap::{MmapRange, MmapXenFlags};
-
 #[cfg(all(feature = "xen", unix))]
-pub use mmap_xen::{GuestMemoryXen, MmapRegion as MmapRegionXen};
+pub use mmap_xen::{GuestMemoryXen, MmapRange, MmapRegion as MmapRegionXen, MmapXenFlags};
 
-#[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
-pub use mmap_unix::{Error as MmapRegionError, GuestMemoryMmap, GuestRegionMmap, MmapRegion};
+#[cfg(all(feature = "backend-mmap", unix))]
+pub use mmap_unix::{
+    Error as MmapRegionError, GuestMemoryMmap, GuestRegionMmap, MmapRegion, MmapRegionBuilder,
+};
 
 #[cfg(windows)]
 pub use crate::mmap_windows::{

src/mmap.rs

@@ -19,12 +19,6 @@ use std::result;
 use crate::bitmap::Bitmap;
 use crate::guest_memory::FileOffset;
 
-#[cfg(all(not(feature = "xen"), unix))]
-pub use crate::mmap_unix::{Error as MmapRegionError, MmapRegion, MmapRegionBuilder};
-
-#[cfg(all(feature = "xen", unix))]
-pub use crate::mmap_xen::{Error as MmapRegionError, MmapRange, MmapRegion, MmapXenFlags};
-
 /// A `Bitmap` that can be created starting from an initial size.
 pub trait NewBitmap: Bitmap + Default {
     /// Create a new object based on the specified length in bytes.
@@ -90,7 +84,8 @@ pub(crate) mod tests {
     use crate::bitmap::BS;
     use crate::{
         guest_memory, Address, Bytes, GuestAddress, GuestMemory, GuestMemoryError,
-        GuestMemoryRegion, GuestUsize, MemoryRegionAddress, VolatileMemory, VolatileSlice,
+        GuestMemoryRegion, GuestUsize, MemoryRegionAddress, MmapRegion, VolatileMemory,
+        VolatileSlice,
     };
 
     use std::io::Write;
@@ -154,7 +149,7 @@ pub(crate) mod tests {
     any_backend! {
         #[cfg(all(windows, feature = "backend-mmap"))]
         Windows[crate::mmap_windows::GuestRegionWindows<()>],
-        #[cfg(all(unix, feature = "backend-mmap", not(feature = "xen")))]
+        #[cfg(all(unix, feature = "backend-mmap"))]
         Mmap[crate::mmap_unix::GuestRegionMmap<()>],
         #[cfg(all(unix, feature = "backend-mmap", feature = "xen"))]
         Xen[crate::mmap_xen::MmapRegion]
@@ -173,7 +168,7 @@ pub(crate) mod tests {
                 )
                 .unwrap(),
             ));
-            #[cfg(all(unix, feature = "backend-mmap", not(feature = "xen")))]
+            #[cfg(all(unix, feature = "backend-mmap"))]
             regions.push(AnyRegion::Mmap(
                 crate::mmap_unix::GuestRegionMmap::new(
                     MmapRegion::from_file(f_off.clone(), size).unwrap(),
@@ -183,8 +178,12 @@ pub(crate) mod tests {
             ));
             #[cfg(all(unix, feature = "backend-mmap", feature = "xen"))]
             regions.push(AnyRegion::Xen(
-                MmapRegion::from_range(MmapRange::new_unix(size, Some(f_off.clone()), addr))
-                    .unwrap(),
+                crate::MmapRegionXen::from_range(crate::MmapRange::new_unix(
+                    size,
+                    Some(f_off.clone()),
+                    addr,
+                ))
+                .unwrap(),
             ));
             regions
         }
@@ -203,14 +202,15 @@ pub(crate) mod tests {
                 )
                 .unwrap(),
             ));
-            #[cfg(all(unix, feature = "backend-mmap", not(feature = "xen")))]
+            #[cfg(all(unix, feature = "backend-mmap"))]
             regions.push(AnyRegion::Mmap(
                 crate::mmap_unix::GuestRegionMmap::new(MmapRegion::new(size).unwrap(), addr)
                     .unwrap(),
             ));
             #[cfg(all(unix, feature = "backend-mmap", feature = "xen"))]
             regions.push(AnyRegion::Xen(
-                MmapRegion::from_range(MmapRange::new_unix(size, None, addr)).unwrap(),
+                crate::MmapRegionXen::from_range(crate::MmapRange::new_unix(size, None, addr))
+                    .unwrap(),
             ));
             regions
         }

src/region.rs

@@ -97,7 +97,7 @@ pub trait GuestMemoryRegion: Bytes<MemoryRegionAddress, E = GuestMemoryError> {
     /// # Examples (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
     /// # use vm_memory::{GuestAddress, MmapRegion, GuestRegionMmap, GuestMemoryRegion};
     /// # use vm_memory::volatile_memory::{VolatileMemory, VolatileSlice, VolatileRef};
@@ -127,7 +127,7 @@ pub trait GuestMemoryRegion: Bytes<MemoryRegionAddress, E = GuestMemoryError> {
     /// # Examples (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
     /// #   use vm_memory::{GuestAddress, GuestMemory, GuestMemoryMmap, GuestRegionMmap};
     /// let addr = GuestAddress(0x1000);
@@ -302,10 +302,10 @@ impl<R: GuestMemoryRegion> Bytes<MemoryRegionAddress> for R {
     /// * Write a slice at guest address 0x1200.
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # use vm_memory::{Bytes, GuestAddress, GuestMemoryMmap};
     /// #
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
     /// # let start_addr = GuestAddress(0x1000);
     /// # let mut gm = GuestMemoryMmap::<()>::from_ranges(&vec![(start_addr, 0x400)])
@@ -328,10 +328,10 @@ impl<R: GuestMemoryRegion> Bytes<MemoryRegionAddress> for R {
     /// * Read a slice of length 16 at guestaddress 0x1200.
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # use vm_memory::{Bytes, GuestAddress, GuestMemoryMmap};
     /// #
-    /// # #[cfg(all(feature = "backend-mmap", unix, not(feature = "xen")))]
+    /// # #[cfg(all(feature = "backend-mmap", unix))]
     /// # {
     /// # let start_addr = GuestAddress(0x1000);
     /// # let mut gm = GuestMemoryMmap::<()>::from_ranges(&vec![(start_addr, 0x400)])