[PATCH 10/12] rust: memory: wrap MemoryRegion with Opaque<>

[Paolo Bonzini <pbonzini@redhat.com>]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 rust/qemu-api/src/bindings.rs |  3 ---
 rust/qemu-api/src/memory.rs   | 35 +++++++++++++++++++++--------------
 2 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/rust/qemu-api/src/bindings.rs b/rust/qemu-api/src/bindings.rs
index b791ca6d87f..26cc8de0cf2 100644
--- a/rust/qemu-api/src/bindings.rs
+++ b/rust/qemu-api/src/bindings.rs
@@ -34,9 +34,6 @@ unsafe impl Sync for CharBackend {}
 unsafe impl Send for Chardev {}
 unsafe impl Sync for Chardev {}
 
-unsafe impl Send for MemoryRegion {}
-unsafe impl Sync for MemoryRegion {}
-
 unsafe impl Send for ObjectClass {}
 unsafe impl Sync for ObjectClass {}
 
diff --git a/rust/qemu-api/src/memory.rs b/rust/qemu-api/src/memory.rs
index 713c494ca2e..eff9f09fd7f 100644
--- a/rust/qemu-api/src/memory.rs
+++ b/rust/qemu-api/src/memory.rs
@@ -6,9 +6,8 @@
 
 use std::{
     ffi::{CStr, CString},
-    marker::{PhantomData, PhantomPinned},
+    marker::PhantomData,
     os::raw::{c_uint, c_void},
-    ptr::addr_of,
 };
 
 pub use bindings::{hwaddr, MemTxAttrs};
@@ -16,6 +15,7 @@
 use crate::{
     bindings::{self, device_endian, memory_region_init_io},
     callbacks::FnCall,
+    cell::Opaque,
     prelude::*,
     zeroable::Zeroable,
 };
@@ -132,13 +132,13 @@ fn default() -> Self {
     }
 }
 
-/// A safe wrapper around [`bindings::MemoryRegion`].  Compared to the
-/// underlying C struct it is marked as pinned because the QOM tree
-/// contains a pointer to it.
-pub struct MemoryRegion {
-    inner: bindings::MemoryRegion,
-    _pin: PhantomPinned,
-}
+/// A safe wrapper around [`bindings::MemoryRegion`].
+#[repr(transparent)]
+#[derive(qemu_api_macros::Wrapper)]
+pub struct MemoryRegion(Opaque<bindings::MemoryRegion>);
+
+unsafe impl Send for MemoryRegion {}
+unsafe impl Sync for MemoryRegion {}
 
 impl MemoryRegion {
     // inline to ensure that it is not included in tests, which only
@@ -174,13 +174,20 @@ pub fn init_io<T: IsA<Object>>(
         size: u64,
     ) {
         unsafe {
-            Self::do_init_io(&mut self.inner, owner.cast::<Object>(), &ops.0, name, size);
+            Self::do_init_io(
+                // self.0.as_mut_ptr() needed because Rust tries to call
+                // ObjectDeref::as_mut_ptr() on "&mut Self", instead of coercing
+                // to "&Self" and then calling MemoryRegion::as_mut_ptr().
+                // Revisit if/when ObjectCastMut is not needed anymore; it is
+                // only used in a couple places for initialization.
+                self.0.as_mut_ptr(),
+                owner.cast::<Object>(),
+                &ops.0,
+                name,
+                size,
+            );
         }
     }
-
-    pub(crate) const fn as_mut_ptr(&self) -> *mut bindings::MemoryRegion {
-        addr_of!(self.inner) as *mut _
-    }
 }
 
 unsafe impl ObjectType for MemoryRegion {
-- 
2.48.1