rust/hpet: return errors from realize if properties are incorrect

Match the code in hpet.c; this also allows removing the
BqlCell from the num_timers field.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 10 insertions, 13 deletions

diff --git a/rust/hw/timer/hpet/src/device.rs b/rust/hw/timer/hpet/src/device.rs
index a957de1..cd439f9 100644
--- a/rust/hw/timer/hpet/src/device.rs
+++ b/rust/hw/timer/hpet/src/device.rs
@@ -725,18 +725,16 @@ impl HPETState {
     }
 
     fn realize(&self) -> qemu_api::Result<()> {
+        if self.num_timers.get() < HPET_MIN_TIMERS || self.num_timers.get() > HPET_MAX_TIMERS {
+            Err(format!(
+                "hpet.num_timers must be between {HPET_MIN_TIMERS} and {HPET_MAX_TIMERS}"
+            ))?;
+        }
         if self.int_route_cap == 0 {
-            // TODO: Add error binding: warn_report()
-            println!("Hpet's hpet-intcap property not initialized");
+            Err("hpet.hpet-intcap property not initialized")?;
         }
 
-        self.hpet_id.set(HPETFwConfig::assign_hpet_id());
-
-        if self.num_timers.get() < HPET_MIN_TIMERS {
-            self.num_timers.set(HPET_MIN_TIMERS);
-        } else if self.num_timers.get() > HPET_MAX_TIMERS {
-            self.num_timers.set(HPET_MAX_TIMERS);
-        }
+        self.hpet_id.set(HPETFwConfig::assign_hpet_id()?);
 
         self.init_timer();
         // 64-bit General Capabilities and ID Register; LegacyReplacementRoute.
diff --git a/rust/hw/timer/hpet/src/fw_cfg.rs b/rust/hw/timer/hpet/src/fw_cfg.rs
index 6c10316..619d662 100644
--- a/rust/hw/timer/hpet/src/fw_cfg.rs
+++ b/rust/hw/timer/hpet/src/fw_cfg.rs
@@ -36,7 +36,7 @@ pub static mut hpet_fw_cfg: HPETFwConfig = HPETFwConfig {
 };
 
 impl HPETFwConfig {
-    pub(crate) fn assign_hpet_id() -> usize {
+    pub(crate) fn assign_hpet_id() -> Result<usize, &'static str> {
         assert!(bql_locked());
         // SAFETY: all accesses go through these methods, which guarantee
         // that the accesses are protected by the BQL.
@@ -48,13 +48,12 @@ impl HPETFwConfig {
         }
 
         if fw_cfg.count == 8 {
-            // TODO: Add error binding: error_setg()
-            panic!("Only 8 instances of HPET is allowed");
+            Err("Only 8 instances of HPET are allowed")?;
         }
 
         let id: usize = fw_cfg.count.into();
         fw_cfg.count += 1;
-        id
+        Ok(id)
     }
 
     pub(crate) fn update_hpet_cfg(hpet_id: usize, timer_block_id: u32, address: u64) {