[PATCH] rust: hpet: fix fw_cfg handling

[PATCH] rust: hpet: fix fw_cfg handling

[Paolo Bonzini]

HPET ids for fw_cfg are not assigned correctly, because there
is a read but no write.  This is caught by nightly Rust as
an unused-assignments warning, so fix it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 rust/hw/timer/hpet/src/fw_cfg.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rust/hw/timer/hpet/src/fw_cfg.rs b/rust/hw/timer/hpet/src/fw_cfg.rs
index e569b57b93b..bb4ea8909ad 100644
--- a/rust/hw/timer/hpet/src/fw_cfg.rs
+++ b/rust/hw/timer/hpet/src/fw_cfg.rs
@@ -40,7 +40,7 @@ pub(crate) fn assign_hpet_id() -> Result<usize, &'static str> {
         assert!(bql::is_locked());
         // SAFETY: all accesses go through these methods, which guarantee
         // that the accesses are protected by the BQL.
-        let mut fw_cfg = unsafe { *addr_of_mut!(hpet_fw_cfg) };
+        let fw_cfg = unsafe { &mut *addr_of_mut!(hpet_fw_cfg) };
 
         if fw_cfg.count == u8::MAX {
             // first instance
@@ -60,7 +60,7 @@ pub(crate) fn update_hpet_cfg(hpet_id: usize, timer_block_id: u32, address: u64)
         assert!(bql::is_locked());
         // SAFETY: all accesses go through these methods, which guarantee
         // that the accesses are protected by the BQL.
-        let mut fw_cfg = unsafe { *addr_of_mut!(hpet_fw_cfg) };
+        let fw_cfg = unsafe { &mut *addr_of_mut!(hpet_fw_cfg) };
 
         fw_cfg.hpet[hpet_id].event_timer_block_id = timer_block_id;
         fw_cfg.hpet[hpet_id].address = address;
-- 
2.51.0

Re: [PATCH] rust: hpet: fix fw_cfg handling

[Zhao Liu]

On Mon, Oct 13, 2025 at 06:52:51PM +0200, Paolo Bonzini wrote:
> Date: Mon, 13 Oct 2025 18:52:51 +0200
> From: Paolo Bonzini <pbonzini@redhat.com>
> Subject: [PATCH] rust: hpet: fix fw_cfg handling
> X-Mailer: git-send-email 2.51.0
> 
> HPET ids for fw_cfg are not assigned correctly, because there
> is a read but no write.  This is caught by nightly Rust as
> an unused-assignments warning, so fix it.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  rust/hw/timer/hpet/src/fw_cfg.rs | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Oops, thanks for this fix.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>