From: Zhao Liu <zhao1.liu@intel.com>

Implement helper accessors as methods of HPETTimerRegisters. Then
HPETTimerRegisters can be accessed without going through HPETTimer or
HPETState.

In subsequent refactoring, HPETTimerRegisters will be maintained at the
HPETState level. However, accessing it through HPETState requires the
lock (lock BQL or mutex), which would cause troublesome nested locks or
reentrancy issues.

Therefore, refactor the accessors of HPETTimerRegisters to bypass
HPETTimer or HPETState.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20251113051937.4017675-12-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 rust/hw/timer/hpet/src/device.rs | 108 ++++++++++++++++---------------
 1 file changed, 55 insertions(+), 53 deletions(-)

diff --git a/rust/hw/timer/hpet/src/device.rs b/rust/hw/timer/hpet/src/device.rs
index 1bdee064d43..8dc3cc59c98 100644
--- a/rust/hw/timer/hpet/src/device.rs
+++ b/rust/hw/timer/hpet/src/device.rs
@@ -186,6 +186,41 @@ pub struct HPETTimerRegisters {
     fsb: u64,
 }
 
+impl HPETTimerRegisters {
+    const fn is_fsb_route_enabled(&self) -> bool {
+        self.config & (1 << HPET_TN_CFG_FSB_ENABLE_SHIFT) != 0
+    }
+
+    const fn is_periodic(&self) -> bool {
+        self.config & (1 << HPET_TN_CFG_PERIODIC_SHIFT) != 0
+    }
+
+    const fn is_int_enabled(&self) -> bool {
+        self.config & (1 << HPET_TN_CFG_INT_ENABLE_SHIFT) != 0
+    }
+
+    const fn is_32bit_mod(&self) -> bool {
+        self.config & (1 << HPET_TN_CFG_32BIT_SHIFT) != 0
+    }
+
+    const fn is_valset_enabled(&self) -> bool {
+        self.config & (1 << HPET_TN_CFG_SETVAL_SHIFT) != 0
+    }
+
+    /// True if timer interrupt is level triggered; otherwise, edge triggered.
+    const fn is_int_level_triggered(&self) -> bool {
+        self.config & (1 << HPET_TN_CFG_INT_TYPE_SHIFT) != 0
+    }
+
+    const fn clear_valset(&mut self) {
+        self.config &= !(1 << HPET_TN_CFG_SETVAL_SHIFT);
+    }
+
+    const fn get_individual_route(&self) -> usize {
+        ((self.config & HPET_TN_CFG_INT_ROUTE_MASK) >> HPET_TN_CFG_INT_ROUTE_SHIFT) as usize
+    }
+}
+
 /// HPET Timer Abstraction
 #[repr(C)]
 #[derive(Debug)]
@@ -248,40 +283,11 @@ fn is_int_active(&self) -> bool {
         self.get_state().is_timer_int_active(self.index.into())
     }
 
-    const fn is_fsb_route_enabled(&self) -> bool {
-        self.regs.config & (1 << HPET_TN_CFG_FSB_ENABLE_SHIFT) != 0
-    }
-
-    const fn is_periodic(&self) -> bool {
-        self.regs.config & (1 << HPET_TN_CFG_PERIODIC_SHIFT) != 0
-    }
-
-    const fn is_int_enabled(&self) -> bool {
-        self.regs.config & (1 << HPET_TN_CFG_INT_ENABLE_SHIFT) != 0
-    }
-
-    const fn is_32bit_mod(&self) -> bool {
-        self.regs.config & (1 << HPET_TN_CFG_32BIT_SHIFT) != 0
-    }
-
-    const fn is_valset_enabled(&self) -> bool {
-        self.regs.config & (1 << HPET_TN_CFG_SETVAL_SHIFT) != 0
-    }
-
-    fn clear_valset(&mut self) {
-        self.regs.config &= !(1 << HPET_TN_CFG_SETVAL_SHIFT);
-    }
-
-    /// True if timer interrupt is level triggered; otherwise, edge triggered.
-    const fn is_int_level_triggered(&self) -> bool {
-        self.regs.config & (1 << HPET_TN_CFG_INT_TYPE_SHIFT) != 0
-    }
-
     /// calculate next value of the general counter that matches the
     /// target (either entirely, or the low 32-bit only depending on
     /// the timer mode).
     fn calculate_cmp64(&self, cur_tick: u64, target: u64) -> u64 {
-        if self.is_32bit_mod() {
+        if self.regs.is_32bit_mod() {
             let mut result: u64 = cur_tick.deposit(0, 32, target);
             if result < cur_tick {
                 result += 0x100000000;
@@ -292,10 +298,6 @@ fn calculate_cmp64(&self, cur_tick: u64, target: u64) -> u64 {
         }
     }
 
-    const fn get_individual_route(&self) -> usize {
-        ((self.regs.config & HPET_TN_CFG_INT_ROUTE_MASK) >> HPET_TN_CFG_INT_ROUTE_SHIFT) as usize
-    }
-
     fn get_int_route(&self) -> usize {
         if self.index <= 1 && self.get_state().is_legacy_mode() {
             // If LegacyReplacement Route bit is set, HPET specification requires
@@ -317,15 +319,15 @@ fn get_int_route(&self) -> usize {
             // ...
             // If the LegacyReplacement Route bit is not set, the individual
             // routing bits for each of the timers are used.
-            self.get_individual_route()
+            self.regs.get_individual_route()
         }
     }
 
     fn set_irq(&self, set: bool) {
         let route = self.get_int_route();
 
-        if set && self.is_int_enabled() && self.get_state().is_hpet_enabled() {
-            if self.is_fsb_route_enabled() {
+        if set && self.regs.is_int_enabled() && self.get_state().is_hpet_enabled() {
+            if self.regs.is_fsb_route_enabled() {
                 // SAFETY:
                 // the parameters are valid.
                 unsafe {
@@ -337,12 +339,12 @@ fn set_irq(&self, set: bool) {
                         null_mut(),
                     );
                 }
-            } else if self.is_int_level_triggered() {
+            } else if self.regs.is_int_level_triggered() {
                 self.get_state().irqs[route].raise();
             } else {
                 self.get_state().irqs[route].pulse();
             }
-        } else if !self.is_fsb_route_enabled() {
+        } else if !self.regs.is_fsb_route_enabled() {
             self.get_state().irqs[route].lower();
         }
     }
@@ -352,7 +354,7 @@ fn update_irq(&self, set: bool) {
         // still operate and generate appropriate status bits, but
         // will not cause an interrupt"
         self.get_state()
-            .update_int_status(self.index.into(), set && self.is_int_level_triggered());
+            .update_int_status(self.index.into(), set && self.regs.is_int_level_triggered());
         self.set_irq(set);
     }
 
@@ -360,7 +362,7 @@ fn arm_timer(&mut self, tick: u64) {
         let mut ns = self.get_state().get_ns(tick);
 
         // Clamp period to reasonable min value (1 us)
-        if self.is_periodic() && ns - self.last < 1000 {
+        if self.regs.is_periodic() && ns - self.last < 1000 {
             ns = self.last + 1000;
         }
 
@@ -373,10 +375,10 @@ fn set_timer(&mut self) {
 
         self.wrap_flag = 0;
         self.cmp64 = self.calculate_cmp64(cur_tick, self.regs.cmp);
-        if self.is_32bit_mod() {
+        if self.regs.is_32bit_mod() {
             // HPET spec says in one-shot 32-bit mode, generate an interrupt when
             // counter wraps in addition to an interrupt with comparator match.
-            if !self.is_periodic() && self.cmp64 > hpet_next_wrap(cur_tick) {
+            if !self.regs.is_periodic() && self.cmp64 > hpet_next_wrap(cur_tick) {
                 self.wrap_flag = 1;
                 self.arm_timer(hpet_next_wrap(cur_tick));
                 return;
@@ -418,7 +420,7 @@ fn set_tn_cfg_reg(&mut self, shift: u32, len: u32, val: u64) {
             self.update_irq(true);
         }
 
-        if self.is_32bit_mod() {
+        if self.regs.is_32bit_mod() {
             self.regs.cmp = u64::from(self.regs.cmp as u32); // truncate!
             self.period = u64::from(self.period as u32); // truncate!
         }
@@ -433,7 +435,7 @@ fn set_tn_cmp_reg(&mut self, shift: u32, len: u32, val: u64) {
         let mut length = len;
         let mut value = val;
 
-        if self.is_32bit_mod() {
+        if self.regs.is_32bit_mod() {
             // High 32-bits are zero, leave them untouched.
             if shift != 0 {
                 trace::trace_hpet_ram_write_invalid_tn_cmp();
@@ -445,15 +447,15 @@ fn set_tn_cmp_reg(&mut self, shift: u32, len: u32, val: u64) {
 
         trace::trace_hpet_ram_write_tn_cmp((shift / 8).try_into().unwrap());
 
-        if !self.is_periodic() || self.is_valset_enabled() {
+        if !self.regs.is_periodic() || self.regs.is_valset_enabled() {
             self.regs.cmp = self.regs.cmp.deposit(shift, length, value);
         }
 
-        if self.is_periodic() {
+        if self.regs.is_periodic() {
             self.period = self.period.deposit(shift, length, value);
         }
 
-        self.clear_valset();
+        self.regs.clear_valset();
         if self.get_state().is_hpet_enabled() {
             self.set_timer();
         }
@@ -484,11 +486,11 @@ fn callback(&mut self) {
         let period: u64 = self.period;
         let cur_tick: u64 = self.get_state().get_ticks();
 
-        if self.is_periodic() && period != 0 {
+        if self.regs.is_periodic() && period != 0 {
             while hpet_time_after(cur_tick, self.cmp64) {
                 self.cmp64 += period;
             }
-            if self.is_32bit_mod() {
+            if self.regs.is_32bit_mod() {
                 self.regs.cmp = u64::from(self.cmp64 as u32); // truncate!
             } else {
                 self.regs.cmp = self.cmp64;
@@ -649,7 +651,7 @@ fn set_cfg_reg(&self, shift: u32, len: u32, val: u64) {
             for timer in self.timers.iter().take(self.num_timers) {
                 let mut t = timer.borrow_mut();
 
-                if t.is_int_enabled() && t.is_int_active() {
+                if t.regs.is_int_enabled() && t.is_int_active() {
                     t.update_irq(true);
                 }
                 t.set_timer();
@@ -806,8 +808,8 @@ fn read(&self, addr: hwaddr, size: u32) -> u64 {
 
         let HPETAddrDecode { shift, target, .. } = self.decode(addr, size);
 
-        use GlobalRegister::*;
         use DecodedRegister::*;
+        use GlobalRegister::*;
         (match target {
             Timer(timer, tn_target) => timer.borrow_mut().read(tn_target),
             Global(CAP) => self.capability.get(), /* including HPET_PERIOD 0x004 */
@@ -836,8 +838,8 @@ fn write(&self, addr: hwaddr, value: u64, size: u32) {
 
         trace::trace_hpet_ram_write(addr, value);
 
-        use GlobalRegister::*;
         use DecodedRegister::*;
+        use GlobalRegister::*;
         match target {
             Timer(timer, tn_target) => timer.borrow_mut().write(tn_target, value, shift, len),
             Global(CAP) => {} // General Capabilities and ID Register: Read Only
-- 
2.52.0