Re: [PATCH v2 10/17] vfio/container: Discover IOMMU type before creating the container

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

On 6/17/24 08:34, Cédric Le Goater wrote:
> Since the QEMU struct type representing the VFIO container is deduced
> from the IOMMU type exposed by the host, this type should be well
> defined *before* creating the container struct. This will be necessary
> to instantiate a QOM object of the correct type in future changes.
>
> Rework vfio_set_iommu() to extract the part doing the container
> initialization and move it under vfio_create_container().
>
> Signed-off-by: Cédric Le Goater <clg@redhat.com>
> Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> ---
>  hw/vfio/container.c | 47 ++++++++++++++++++++++-----------------------
>  1 file changed, 23 insertions(+), 24 deletions(-)
>
> diff --git a/hw/vfio/container.c b/hw/vfio/container.c
> index a8691942791006f44f7a3c34b32c67ca51766182..31bdc46a96d1626b237227a25007957e1d472757 100644
> --- a/hw/vfio/container.c
> +++ b/hw/vfio/container.c
> @@ -389,54 +389,56 @@ static const char *vfio_get_iommu_class_name(int iommu_type)
>      };
>  }
>  
> -static bool vfio_set_iommu(VFIOContainer *container, int group_fd,
> -                           Error **errp)
> +static bool vfio_set_iommu(int container_fd, int group_fd,
> +                           int *iommu_type, Error **errp)
>  {
> -    int iommu_type;
> -    const VFIOIOMMUClass *vioc;
> -    const char *vioc_name;
> -
> -    iommu_type = vfio_get_iommu_type(container->fd, errp);
> -    if (iommu_type < 0) {
> -        return false;
> -    }
> -
> -    if (ioctl(group_fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) {
> +    if (ioctl(group_fd, VFIO_GROUP_SET_CONTAINER, &container_fd)) {
>          error_setg_errno(errp, errno, "Failed to set group container");
>          return false;
>      }
>  
> -    while (ioctl(container->fd, VFIO_SET_IOMMU, iommu_type)) {
> -        if (iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) {
> +    while (ioctl(container_fd, VFIO_SET_IOMMU, *iommu_type)) {
> +        if (*iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) {
>              /*
>               * On sPAPR, despite the IOMMU subdriver always advertises v1 and
>               * v2, the running platform may not support v2 and there is no
>               * way to guess it until an IOMMU group gets added to the container.
>               * So in case it fails with v2, try v1 as a fallback.
>               */
> -            iommu_type = VFIO_SPAPR_TCE_IOMMU;
> +            *iommu_type = VFIO_SPAPR_TCE_IOMMU;
>              continue;
>          }
>          error_setg_errno(errp, errno, "Failed to set iommu for container");
>          return false;
>      }
>  
> -    container->iommu_type = iommu_type;
> -
> -    vioc_name = vfio_get_iommu_class_name(iommu_type);
> -    vioc = VFIO_IOMMU_CLASS(object_class_by_name(vioc_name));
> -
> -    vfio_container_init(&container->bcontainer, vioc);
>      return true;
>  }
>  
>  static VFIOContainer *vfio_create_container(int fd, VFIOGroup *group,
>                                              Error **errp)
>  {
> +    int iommu_type;
> +    const VFIOIOMMUClass *vioc;
> +    const char *vioc_name;
>      VFIOContainer *container;
>  
> +    iommu_type = vfio_get_iommu_type(fd, errp);
> +    if (iommu_type < 0) {
> +        return NULL;
> +    }
> +
> +    if (!vfio_set_iommu(fd, group->fd, &iommu_type, errp)) {
> +        return NULL;
> +    }
> +
> +    vioc_name = vfio_get_iommu_class_name(iommu_type);
> +    vioc = VFIO_IOMMU_CLASS(object_class_by_name(vioc_name));
> +
>      container = g_malloc0(sizeof(*container));
>      container->fd = fd;
> +    container->iommu_type = iommu_type;
> +    vfio_container_init(&container->bcontainer, vioc);
>      return container;
>  }
>  
> @@ -618,9 +620,6 @@ static bool vfio_connect_container(VFIOGroup *group, AddressSpace *as,
>      if (!container) {
>          goto close_fd_exit;
>      }
> -    if (!vfio_set_iommu(container, group->fd, errp)) {
> -        goto free_container_exit;
> -    }
>      bcontainer = &container->bcontainer;
>  
>      if (!vfio_cpr_register_container(bcontainer, errp)) {