Re: [PATCH v4 14/14] iommu/arm-smmu-v3: Report events that belong to devices attached to vIOMMU

[Baolu Lu]

On 1/4/25 03:43, Nicolin Chen wrote:
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index 0a08aa82e7cc..55e3d5a14cca 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -1016,9 +1016,24 @@ struct iommu_ioas_change_process {
>   /**
>    * enum iommu_veventq_type - Virtual Event Queue Type
>    * @IOMMU_VEVENTQ_TYPE_DEFAULT: Reserved for future use
> + * @IOMMU_VEVENTQ_TYPE_ARM_SMMUV3: ARM SMMUv3 Virtual Event Queue
>    */
>   enum iommu_veventq_type {
>   	IOMMU_VEVENTQ_TYPE_DEFAULT = 0,
> +	IOMMU_VEVENTQ_TYPE_ARM_SMMUV3 = 1,
> +};
> +
> +/**
> + * struct iommu_vevent_arm_smmuv3 - ARM SMMUv3 Virtual Event
> + *                                  (IOMMU_VEVENTQ_TYPE_ARM_SMMUV3)
> + * @evt: 256-bit ARM SMMUv3 Event record, little-endian.
> + *       (Refer to "7.3 Event records" in SMMUv3 HW Spec)
> + *
> + * StreamID field reports a virtual device ID. To receive a virtual event for a
> + * device, a vDEVICE must be allocated via IOMMU_VDEVICE_ALLOC.
> + */
> +struct iommu_vevent_arm_smmuv3 {
> +	__aligned_le64 evt[4];
>   };

Nit: I think it would be more readable to add a check in the vevent
reporting helper.

diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index 77c34f8791ef..ccada0ada5ff 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -86,6 +86,9 @@ int iommufd_viommu_report_event(struct iommufd_viommu 
*viommu,
        if (WARN_ON_ONCE(!data_len || !event_data))
                return -EINVAL;

+       if (WARN_ON_ONCE(type != IOMMU_VEVENTQ_TYPE_ARM_SMMUV3))
+               return -EINVAL;
+
        down_read(&viommu->veventqs_rwsem);

        veventq = iommufd_viommu_find_veventq(viommu, type);

Or perhaps the compiler could automatically make a warning if the @type
is not one of those values in enum iommu_veventq_type?

Others look good to me.

Thanks,
baolu