scsi: mpi3mr: Serialize admin queue BAR writes on 32-bit systems

On 32-bit systems, 64-bit BAR writes to admin queue registers are
performed as two 32-bit writes. Without locking, this can cause partial
writes when accessed concurrently.

Updated per-queue spinlocks is used to serialize these writes and prevent
race conditions.

Fixes: 824a156 ("scsi: mpi3mr: Base driver code")
Cc: stable@vger.kernel.org
Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
Link: https://lore.kernel.org/r/20250627194539.48851-4-ranjan.kumar@broadcom.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Ranjan Kumar

drivers/scsi/mpi3mr/mpi3mr.h

@@ -1137,6 +1137,8 @@ struct scmd_priv {
  * @logdata_buf: Circular buffer to store log data entries
  * @logdata_buf_idx: Index of entry in buffer to store
  * @logdata_entry_sz: log data entry size
+ * @adm_req_q_bar_writeq_lock: Admin request queue lock
+ * @adm_reply_q_bar_writeq_lock: Admin reply queue lock
  * @pend_large_data_sz: Counter to track pending large data
  * @io_throttle_data_length: I/O size to track in 512b blocks
  * @io_throttle_high: I/O size to start throttle in 512b blocks
@@ -1339,6 +1341,8 @@ struct mpi3mr_ioc {
 	u8 *logdata_buf;
 	u16 logdata_buf_idx;
 	u16 logdata_entry_sz;
+	spinlock_t adm_req_q_bar_writeq_lock;
+	spinlock_t adm_reply_q_bar_writeq_lock;
 
 	atomic_t pend_large_data_sz;
 	u32 io_throttle_data_length;

drivers/scsi/mpi3mr/mpi3mr_fw.c

@@ -23,17 +23,22 @@ module_param(poll_queues, int, 0444);
 MODULE_PARM_DESC(poll_queues, "Number of queues for io_uring poll mode. (Range 1 - 126)");
 
 #if defined(writeq) && defined(CONFIG_64BIT)
-static inline void mpi3mr_writeq(__u64 b, void __iomem *addr)
+static inline void mpi3mr_writeq(__u64 b, void __iomem *addr,
+	spinlock_t *write_queue_lock)
 {
 	writeq(b, addr);
 }
 #else
-static inline void mpi3mr_writeq(__u64 b, void __iomem *addr)
+static inline void mpi3mr_writeq(__u64 b, void __iomem *addr,
+	spinlock_t *write_queue_lock)
 {
 	__u64 data_out = b;
+	unsigned long flags;
 
+	spin_lock_irqsave(write_queue_lock, flags);
 	writel((u32)(data_out), addr);
 	writel((u32)(data_out >> 32), (addr + 4));
+	spin_unlock_irqrestore(write_queue_lock, flags);
 }
 #endif
 
@@ -2954,9 +2959,11 @@ static int mpi3mr_setup_admin_qpair(struct mpi3mr_ioc *mrioc)
 	    (mrioc->num_admin_req);
 	writel(num_admin_entries, &mrioc->sysif_regs->admin_queue_num_entries);
 	mpi3mr_writeq(mrioc->admin_req_dma,
-	    &mrioc->sysif_regs->admin_request_queue_address);
+		&mrioc->sysif_regs->admin_request_queue_address,
+		&mrioc->adm_req_q_bar_writeq_lock);
 	mpi3mr_writeq(mrioc->admin_reply_dma,
-	    &mrioc->sysif_regs->admin_reply_queue_address);
+		&mrioc->sysif_regs->admin_reply_queue_address,
+		&mrioc->adm_reply_q_bar_writeq_lock);
 	writel(mrioc->admin_req_pi, &mrioc->sysif_regs->admin_request_queue_pi);
 	writel(mrioc->admin_reply_ci, &mrioc->sysif_regs->admin_reply_queue_ci);
 	return retval;

drivers/scsi/mpi3mr/mpi3mr_os.c

@@ -5365,6 +5365,8 @@ mpi3mr_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	spin_lock_init(&mrioc->tgtdev_lock);
 	spin_lock_init(&mrioc->watchdog_lock);
 	spin_lock_init(&mrioc->chain_buf_lock);
+	spin_lock_init(&mrioc->adm_req_q_bar_writeq_lock);
+	spin_lock_init(&mrioc->adm_reply_q_bar_writeq_lock);
 	spin_lock_init(&mrioc->sas_node_lock);
 	spin_lock_init(&mrioc->trigger_lock);