[PATCH v2 1/3] iommu/riscv: Add command queue lock

[Nutty.Liu]

On 9/1/2026 9:39 PM, fangyu.yu at linux.alibaba.com wrote:
> From: Fangyu Yu <fangyu.yu at linux.alibaba.com>
>
> Add a raw spinlock to the RISC-V IOMMU queue state so command queue
> publishing can be serialized by a later change.
>
> Fixes: 856c0cfe5c5f ("iommu/riscv: Command and fault queue support")
> Signed-off-by: Fangyu Yu <fangyu.yu at linux.alibaba.com>
Reviewed-by: Nutty Liu <nutty.liu at hotmail.com>

Thanks,
Nutty
> ---
>   drivers/iommu/riscv/iommu.c | 1 +
>   drivers/iommu/riscv/iommu.h | 2 ++
>   2 files changed, 3 insertions(+)
>
> diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
> index cec3ddd7ab10..2c0dcc90cf85 100644
> --- a/drivers/iommu/riscv/iommu.c
> +++ b/drivers/iommu/riscv/iommu.c
> @@ -1560,6 +1560,7 @@ int riscv_iommu_init(struct riscv_iommu_device *iommu)
>   	int rc;
>   
>   	RISCV_IOMMU_QUEUE_INIT(&iommu->cmdq, CQ);
> +	raw_spin_lock_init(&iommu->cmdq.lock);
>   	RISCV_IOMMU_QUEUE_INIT(&iommu->fltq, FQ);
>   
>   	rc = riscv_iommu_init_check(iommu);
> diff --git a/drivers/iommu/riscv/iommu.h b/drivers/iommu/riscv/iommu.h
> index 46df79dd5495..5676001548cc 100644
> --- a/drivers/iommu/riscv/iommu.h
> +++ b/drivers/iommu/riscv/iommu.h
> @@ -12,6 +12,7 @@
>   #define _RISCV_IOMMU_H_
>   
>   #include <linux/iommu.h>
> +#include <linux/spinlock.h>
>   #include <linux/types.h>
>   #include <linux/iopoll.h>
>   
> @@ -23,6 +24,7 @@ struct riscv_iommu_queue {
>   	atomic_t prod;				/* unbounded producer allocation index */
>   	atomic_t head;				/* unbounded shadow ring buffer consumer index */
>   	atomic_t tail;				/* unbounded shadow ring buffer producer index */
> +	raw_spinlock_t lock;			/* serialize queue publishing */
>   	unsigned int mask;			/* index mask, queue length - 1 */
>   	unsigned int irq;			/* allocated interrupt number */
>   	struct riscv_iommu_device *iommu;	/* iommu device handling the queue when active */