Re: [dpdk-dev] [PATCH v2] vfio: allow secondary process to query IOMMU type

["Wang, Xiao W" <xiao.w.wang@intel.com>]

Hi Anatoly,

> -----Original Message-----
> From: Burakov, Anatoly
> Sent: Friday, January 18, 2019 6:25 PM
> To: dev@dpdk.org
> Cc: Wang, Xiao W <xiao.w.wang@intel.com>; Zhang, Qi Z
> <qi.z.zhang@intel.com>; qingfu.cqf@alibaba-inc.com; thomas@monjalon.net;
> Stojaczyk, Dariusz <dariusz.stojaczyk@intel.com>; stable@dpdk.org
> Subject: [PATCH v2] vfio: allow secondary process to query IOMMU type
> 
> 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>
> ---
> 
> Notes:
>     v2:
>     - Check if we found our IOMMU type within list of IOMMU types
>     - Don't request new default container fd as this should have
>       been done during rte_vfio_enable()
> 
>  lib/librte_eal/linuxapp/eal/eal_vfio.c        | 88 +++++++++++++++++++
>  lib/librte_eal/linuxapp/eal/eal_vfio.h        | 12 ++-
>  .../linuxapp/eal/eal_vfio_mp_sync.c           | 16 ++++
>  3 files changed, 115 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_eal/linuxapp/eal/eal_vfio.c
> b/lib/librte_eal/linuxapp/eal/eal_vfio.c
> index 72cc65151..c821e8382 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_vfio.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_vfio.c
> @@ -549,6 +549,65 @@ vfio_mem_event_callback(enum rte_mem_event
> type, const void *addr, size_t len,
>  	}
>  }
> 
> +static int
> +vfio_sync_default_container(void)
> +{
> +	struct rte_mp_msg mp_req, *mp_rep;
> +	struct rte_mp_reply mp_reply;
> +	struct timespec ts = {.tv_sec = 5, .tv_nsec = 0};
> +	struct vfio_mp_param *p = (struct vfio_mp_param *)mp_req.param;
> +	int iommu_type_id;
> +	unsigned int i;
> +
> +	/* cannot be called from primary */
> +	if (rte_eal_process_type() != RTE_PROC_SECONDARY)
> +		return -1;
> +
> +	/* default container fd should have been opened in rte_vfio_enable()
> */
> +	if (!default_vfio_cfg->vfio_enabled ||
> +			default_vfio_cfg->vfio_container_fd < 0) {
> +		RTE_LOG(ERR, EAL, "VFIO support is not initialized\n");
> +		return -1;
> +	}
> +
> +	/* find default container's IOMMU type */
> +	p->req = SOCKET_REQ_IOMMU_TYPE;

Since this function is to sync IOMMU type for the default container, should we make the req type as
SOCKET_REQ_DEFAULT_IOMMU_TYPE?

BRs,
Xiao