rust: add bindings for memattrs

The MemTxAttrs structure contains bitfield members, and bindgen is
unable to generate an equivalent macro definition for
MEMTXATTRS_UNSPECIFIED.

Therefore, manually define a global constant variable
MEMTXATTRS_UNSPECIFIED to support calls from Rust code.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250125125137.1223277-6-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/qemu-api/src/memory.rs

@@ -2,7 +2,7 @@
 // Author(s): Paolo Bonzini <pbonzini@redhat.com>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
-//! Bindings for `MemoryRegion` and `MemoryRegionOps`
+//! Bindings for `MemoryRegion`, `MemoryRegionOps` and `MemTxAttrs`
 
 use std::{
     ffi::{CStr, CString},
@@ -11,7 +11,7 @@
     ptr::addr_of,
 };
 
-pub use bindings::hwaddr;
+pub use bindings::{hwaddr, MemTxAttrs};
 
 use crate::{
     bindings::{self, device_endian, memory_region_init_io},
@@ -189,3 +189,15 @@ unsafe impl ObjectType for MemoryRegion {
         unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_MEMORY_REGION) };
 }
 qom_isa!(MemoryRegion: Object);
+
+/// A special `MemTxAttrs` constant, used to indicate that no memory
+/// attributes are specified.
+///
+/// Bus masters which don't specify any attributes will get this,
+/// which has all attribute bits clear except the topmost one
+/// (so that we can distinguish "all attributes deliberately clear"
+/// from "didn't specify" if necessary).
+pub const MEMTXATTRS_UNSPECIFIED: MemTxAttrs = MemTxAttrs {
+    unspecified: true,
+    ..Zeroable::ZERO
+};

rust/qemu-api/src/zeroable.rs

@@ -101,3 +101,4 @@ fn default() -> Self {
 impl_zeroable!(crate::bindings::MemoryRegionOps__bindgen_ty_1);
 impl_zeroable!(crate::bindings::MemoryRegionOps__bindgen_ty_2);
 impl_zeroable!(crate::bindings::MemoryRegionOps);
+impl_zeroable!(crate::bindings::MemTxAttrs);

rust/wrapper.h

@@ -62,3 +62,4 @@ typedef enum memory_order {
 #include "qapi/error.h"
 #include "migration/vmstate.h"
 #include "chardev/char-serial.h"
+#include "exec/memattrs.h"