Re: [PATCH v2 1/4] backends/iommufd: Introduce iommufd_backend_alloc_veventq

[Eric Auger <eric.auger@redhat.com>]

On 12/4/25 10:22 AM, Shameer Kolothum wrote:
> From: Nicolin Chen <nicolinc@nvidia.com>
>
> Add a new helper for IOMMU_VEVENTQ_ALLOC ioctl to allocate a virtual event
> queue (vEVENTQ) for a vIOMMU object.
>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
> ---
>  backends/iommufd.c       | 31 +++++++++++++++++++++++++++++++
>  backends/trace-events    |  1 +
>  include/system/iommufd.h | 12 ++++++++++++
>  3 files changed, 44 insertions(+)
>
> diff --git a/backends/iommufd.c b/backends/iommufd.c
> index 718d63f5cf..633aecd525 100644
> --- a/backends/iommufd.c
> +++ b/backends/iommufd.c
> @@ -503,6 +503,37 @@ bool iommufd_backend_alloc_vdev(IOMMUFDBackend *be, uint32_t dev_id,
>      return true;
>  }
>  
> +bool iommufd_backend_alloc_veventq(IOMMUFDBackend *be, uint32_t viommu_id,
> +                                   uint32_t type, uint32_t depth,
> +                                   uint32_t *out_veventq_id,
> +                                   uint32_t *out_veventq_fd, Error **errp)
> +{
> +    int ret;
> +    struct iommu_veventq_alloc alloc_veventq = {
> +        .size = sizeof(alloc_veventq),
> +        .flags = 0,
> +        .type = type,
> +        .veventq_depth = depth,
> +        .viommu_id = viommu_id,
> +    };
> +
> +    ret = ioctl(be->fd, IOMMU_VEVENTQ_ALLOC, &alloc_veventq);
> +
> +    trace_iommufd_viommu_alloc_eventq(be->fd, viommu_id, type,
> +                                      alloc_veventq.out_veventq_id,
> +                                      alloc_veventq.out_veventq_fd, ret);
> +    if (ret) {
> +        error_setg_errno(errp, errno, "IOMMU_VEVENTQ_ALLOC failed");
> +        return false;
> +    }
> +
> +    g_assert(out_veventq_id);
> +    g_assert(out_veventq_fd);
can it happen if the ioctl succeeds?
> +    *out_veventq_id = alloc_veventq.out_veventq_id;
> +    *out_veventq_fd = alloc_veventq.out_veventq_fd;
> +    return true;
> +}
> +
>  bool host_iommu_device_iommufd_attach_hwpt(HostIOMMUDeviceIOMMUFD *idev,
>                                             uint32_t hwpt_id, Error **errp)
>  {
> diff --git a/backends/trace-events b/backends/trace-events
> index 8408dc8701..5afa7a40be 100644
> --- a/backends/trace-events
> +++ b/backends/trace-events
> @@ -23,3 +23,4 @@ iommufd_backend_get_dirty_bitmap(int iommufd, uint32_t hwpt_id, uint64_t iova, u
>  iommufd_backend_invalidate_cache(int iommufd, uint32_t id, uint32_t data_type, uint32_t entry_len, uint32_t entry_num, uint32_t done_num, uint64_t data_ptr, int ret) " iommufd=%d id=%u data_type=%u entry_len=%u entry_num=%u done_num=%u data_ptr=0x%"PRIx64" (%d)"
>  iommufd_backend_alloc_viommu(int iommufd, uint32_t dev_id, uint32_t type, uint32_t hwpt_id, uint32_t viommu_id, int ret) " iommufd=%d type=%u dev_id=%u hwpt_id=%u viommu_id=%u (%d)"
>  iommufd_backend_alloc_vdev(int iommufd, uint32_t dev_id, uint32_t viommu_id, uint64_t virt_id, uint32_t vdev_id, int ret) " iommufd=%d dev_id=%u viommu_id=%u virt_id=0x%"PRIx64" vdev_id=%u (%d)"
> +iommufd_viommu_alloc_eventq(int iommufd, uint32_t viommu_id, uint32_t type, uint32_t veventq_id, uint32_t veventq_fd, int ret) " iommufd=%d viommu_id=%u type=%u veventq_id=%u veventq_fd=%u (%d)"
> diff --git a/include/system/iommufd.h b/include/system/iommufd.h
> index aa78bf1e1d..9770ff1484 100644
> --- a/include/system/iommufd.h
> +++ b/include/system/iommufd.h
> @@ -56,6 +56,13 @@ typedef struct IOMMUFDVdev {
>      uint32_t virt_id;  /* virtual device ID */
>  } IOMMUFDVdev;
>  
> +/* Virtual event queue interface for a vIOMMU */
> +typedef struct IOMMUFDVeventq {
> +    IOMMUFDViommu *viommu;
> +    uint32_t veventq_id;
> +    uint32_t veventq_fd;
> +} IOMMUFDVeventq;
> +
>  bool iommufd_backend_connect(IOMMUFDBackend *be, Error **errp);
>  void iommufd_backend_disconnect(IOMMUFDBackend *be);
>  
> @@ -86,6 +93,11 @@ bool iommufd_backend_alloc_vdev(IOMMUFDBackend *be, uint32_t dev_id,
>                                  uint32_t viommu_id, uint64_t virt_id,
>                                  uint32_t *out_vdev_id, Error **errp);
>  
> +bool iommufd_backend_alloc_veventq(IOMMUFDBackend *be, uint32_t viommu_id,
> +                                   uint32_t type, uint32_t depth,
> +                                   uint32_t *out_veventq_id,
> +                                   uint32_t *out_veventq_fd, Error **errp);
> +
>  bool iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t hwpt_id,
>                                          bool start, Error **errp);
>  bool iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, uint32_t hwpt_id,
Eric