Re: [PATCH] vfio: allow secondary process to query IOMMU type

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 17-Jan-19 5:30 PM, Anatoly Burakov wrote:
> It is only possible to know IOMMU type of a given VFIO container
> by attempting to initialize it. Since secondary process never
> attempts to set up VFIO container itself (because they're shared
> between primary and secondary), it never knows which IOMMU type
> the container is using, and never sets up the appropriate config
> structures. This results in inability to perform DMA mappings in
> secondary process.
> 
> Fix this by allowing secondary process to query IOMMU type of
> primary's default container at device initialization.
> 
> Note that this fix is assuming we're only interested in default
> container.
> 
> Bugzilla ID: 174
> 
> Fixes: 6bcb7c95fe14 ("vfio: share default container in multi-process")
> Cc: dariusz.stojaczyk@intel.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
> ---

<...>

> +	/* we now have an fd for default container, as well as its IOMMU type.
> +	 * now, set up default VFIO container config to match.
> +	 */
> +	for (i = 0; i < RTE_DIM(iommu_types); i++) {
> +		const struct vfio_iommu_type *t = &iommu_types[i];
> +		if (t->type_id != iommu_type_id)
> +			continue;
> +
> +		/* we found our IOMMU type */
> +		default_vfio_cfg->vfio_enabled = 1;
> +		default_vfio_cfg->vfio_container_fd = vfio_container_fd;
> +		default_vfio_cfg->vfio_iommu_type = t;
> +		break;
> +	}

Self-review: if IOMMU type wasn't found, we still return 0. Will fix in v2.

> +
> +	return 0;
> +}
> +
>   int
>   rte_vfio_clear_group(int vfio_group_fd)
>   {
> @@ -745,6 +805,26 @@ rte_vfio_setup_device(const char *sysfs_base, const char *dev_addr,
>   			else
>   				RTE_LOG(DEBUG, EAL, "Installed memory event callback for VFIO\n");

-- 
Thanks,
Anatoly