Re: [RFC PATCH v3 01/15] backends/iommufd: Introduce iommufd_backend_alloc_viommu

[Jonathan Cameron via <qemu-arm@nongnu.org>]

On Mon, 14 Jul 2025 16:59:27 +0100
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> wrote:

> From: Nicolin Chen <nicolinc@nvidia.com>
> 
> Add a helper to allocate a viommu object.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>

One trivial comment inline. Feel free to ignore.

> ---
>  backends/iommufd.c       | 25 +++++++++++++++++++++++++
>  backends/trace-events    |  1 +
>  include/system/iommufd.h |  4 ++++
>  3 files changed, 30 insertions(+)
> 
> diff --git a/backends/iommufd.c b/backends/iommufd.c
> index 2a33c7ab0b..f3b95ee321 100644
> --- a/backends/iommufd.c
> +++ b/backends/iommufd.c
> @@ -446,6 +446,31 @@ bool iommufd_backend_invalidate_cache(IOMMUFDBackend *be, uint32_t id,
>      return !ret;
>  }
>  
> +bool iommufd_backend_alloc_viommu(IOMMUFDBackend *be, uint32_t dev_id,
> +                                  uint32_t viommu_type, uint32_t hwpt_id,
> +                                  uint32_t *out_viommu_id, Error **errp)
> +{
> +    int ret, fd = be->fd;

Not sure the fd local variable is worth bothering with given be->fd is
very short and you only have a couple of users.

> +    struct iommu_viommu_alloc alloc_viommu = {
> +        .size = sizeof(alloc_viommu),
> +        .type = viommu_type,
> +        .dev_id = dev_id,
> +        .hwpt_id = hwpt_id,
> +    };
> +
> +    ret = ioctl(fd, IOMMU_VIOMMU_ALLOC, &alloc_viommu);
> +
> +    trace_iommufd_backend_alloc_viommu(fd, viommu_type, dev_id, hwpt_id,
> +                                       alloc_viommu.out_viommu_id, ret);
> +    if (ret) {
> +        error_setg_errno(errp, errno, "IOMMU_VIOMMU_ALLOC failed");
> +        return false;
> +    }
> +
> +    *out_viommu_id = alloc_viommu.out_viommu_id;
> +    return true;
> +}