Re: [PATCH] vfio: use right index when tracking devices in a vfio group

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Mon, 8 May 2017 18:44:18 +0100
> From: Alejandro Lucero <alejandro.lucero@netronome.com>
> To: dev@dpdk.org
> CC: anatoly.burakov@intel.com, jerin.jacob@caviumnetworks.com,
>  thomas@monjalon.net
> Subject: [PATCH] vfio: use right index when tracking devices in a vfio group
> X-Mailer: git-send-email 1.9.1
> 
> Previous fix for properly handling devices from the same VFIO group
> introduced another bug where the file descriptor of a kernel vfio
> group is used as the index for tracking number of devices of a vfio
> group struct handled by dpdk vfio code. Instead of the file
> descriptor itself, the vfio group object that file descriptor is
> registered with has to be used.
> 
> This patch introduces specific functions for incrementing or
> decrementing the device counter for a specific vfio group using the
> vfio file descriptor as a parameter. Note the code is not optimized
> as the vfio group is found sequentially going through the vfio group
> array but this should not be a problem as this is not related to
> packet handling at all.
> 
> Fixes: a9c349e3a100 ("vfio: fix device unplug when several devices per group")
> 
> Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>

Tested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

> ---
>  lib/librte_eal/linuxapp/eal/eal_vfio.c | 60 +++++++++++++++++++++++++++-------
>  1 file changed, 49 insertions(+), 11 deletions(-)
> 
> diff --git a/lib/librte_eal/linuxapp/eal/eal_vfio.c b/lib/librte_eal/linuxapp/eal/eal_vfio.c
> index d3eae20..21d126f 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_vfio.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_vfio.c
> @@ -172,6 +172,44 @@
>  	return -1;
>  }
>  
> +
> +static int
> +get_vfio_group_idx(int vfio_group_fd)
> +{
> +	int i;
> +	for (i = 0; i < VFIO_MAX_GROUPS; i++)
> +		if (vfio_cfg.vfio_groups[i].fd == vfio_group_fd)
> +			return i;
> +	return -1;
> +}
> +
> +static void
> +vfio_group_device_get(int vfio_group_fd)
> +{
> +	int i;
> +
> +	i = get_vfio_group_idx(vfio_group_fd);
> +	vfio_cfg.vfio_groups[i].devices++;
> +}
> +
> +static void
> +vfio_group_device_put(int vfio_group_fd)
> +{
> +	int i;
> +
> +	i = get_vfio_group_idx(vfio_group_fd);
> +	vfio_cfg.vfio_groups[i].devices--;
> +}
> +
> +static int
> +vfio_group_device_count(int vfio_group_fd)
> +{
> +	int i;
> +
> +	i = get_vfio_group_idx(vfio_group_fd);
> +	return vfio_cfg.vfio_groups[i].devices;
> +}
> +
>  int
>  clear_group(int vfio_group_fd)
>  {
> @@ -180,15 +218,14 @@
>  
>  	if (internal_config.process_type == RTE_PROC_PRIMARY) {
>  
> -		for (i = 0; i < VFIO_MAX_GROUPS; i++)
> -			if (vfio_cfg.vfio_groups[i].fd == vfio_group_fd) {
> -				vfio_cfg.vfio_groups[i].group_no = -1;
> -				vfio_cfg.vfio_groups[i].fd = -1;
> -				vfio_cfg.vfio_groups[i].devices = 0;
> -				vfio_cfg.vfio_active_groups--;
> -				return 0;
> -			}
> -		return -1;
> +		i = get_vfio_group_idx(vfio_group_fd);
> +		if ( i < 0)
> +			return -1;
> +		vfio_cfg.vfio_groups[i].group_no = -1;
> +		vfio_cfg.vfio_groups[i].fd = -1;
> +		vfio_cfg.vfio_groups[i].devices = 0;
> +		vfio_cfg.vfio_active_groups--;
> +		return 0;
>  	}
>  
>  	/* This is just for SECONDARY processes */
> @@ -358,7 +395,7 @@
>  		clear_group(vfio_group_fd);
>  		return -1;
>  	}
> -	vfio_cfg.vfio_groups[vfio_group_fd].devices++;
> +	vfio_group_device_get(vfio_group_fd);
>  
>  	return 0;
>  }
> @@ -406,7 +443,8 @@
>  	/* An VFIO group can have several devices attached. Just when there is
>  	 * no devices remaining should the group be closed.
>  	 */
> -	if (--vfio_cfg.vfio_groups[vfio_group_fd].devices == 0) {
> +	vfio_group_device_put(vfio_group_fd);
> +	if (!vfio_group_device_count(vfio_group_fd)) {
>  
>  		if (close(vfio_group_fd) < 0) {
>  			RTE_LOG(INFO, EAL, "Error when closing vfio_group_fd for %s\n",
> -- 
> 1.9.1
>