[PULL,11/25] rust: hpet: do not access fields of SysBusDevice

Commit Message

Paolo Bonzini March 9, 2025, 10:31 a.m. UTC

Fields of SysBusDevice must only be accessed with the BQL taken.  Add
a wrapper that verifies that.

Signed-off-by: Paolo Bonzini <[e-mail]>
---
 rust/hw/timer/hpet/src/hpet.rs |  4 +---
 rust/qemu-api/src/sysbus.rs    | 12 ++++++++++++
 2 files changed, 13 insertions(+), 3 deletions(-)

Patch

diff --git a/rust/hw/timer/hpet/src/hpet.rs b/rust/hw/timer/hpet/src/hpet.rs
index 3d3d6ef8eec..d989360ede8 100644
--- a/rust/hw/timer/hpet/src/hpet.rs
+++ b/rust/hw/timer/hpet/src/hpet.rs
@@ -730,8 +730,6 @@  fn realize(&self) {
     }
 
     fn reset_hold(&self, _type: ResetType) {
-        let sbd = self.upcast::<SysBusDevice>();
-
         for timer in self.timers.iter().take(self.num_timers.get()) {
             timer.borrow_mut().reset();
         }
@@ -744,7 +742,7 @@  fn reset_hold(&self, _type: ResetType) {
         HPETFwConfig::update_hpet_cfg(
             self.hpet_id.get(),
             self.capability.get() as u32,
-            sbd.mmio[0].addr,
+            self.mmio_addr(0).unwrap(),
         );
 
         // to document that the RTC lowers its output on reset as well
diff --git a/rust/qemu-api/src/sysbus.rs b/rust/qemu-api/src/sysbus.rs
index 48803a655f9..0790576d446 100644
--- a/rust/qemu-api/src/sysbus.rs
+++ b/rust/qemu-api/src/sysbus.rs
@@ -64,6 +64,18 @@  fn init_irq(&self, irq: &InterruptSource) {
         }
     }
 
+    // TODO: do we want a type like GuestAddress here?
+    fn mmio_addr(&self, id: u32) -> Option<u64> {
+        assert!(bql_locked());
+        let sbd = self.upcast();
+        let id: usize = id.try_into().unwrap();
+        if sbd.mmio[id].memory.is_null() {
+            None
+        } else {
+            Some(sbd.mmio[id].addr)
+        }
+    }
+
     // TODO: do we want a type like GuestAddress here?
     fn mmio_map(&self, id: u32, addr: u64) {
         assert!(bql_locked());