Re: [dpdk-stable] [PATCH 18.08] vfio: don't needlessly setup devices in secondary process

[Kevin Traynor <ktraynor@redhat.com>]

On 11/27/2018 12:58 PM, Darek Stojaczyk wrote:
> Setting up a device that wasn't setup in the primary
> process will possibly break the primary process. That's
> because the IPC message to retrieve the group fd in the
> primary will also *open* that group if it wasn't opened
> before. Even though the secondary process closes that fd
> soon after as a part of its error handling path, the
> primary process leaks it.
> 
> What's worse, opening that fd on the primary will
> increment the process-local counter of opened groups.
> If it was 0 before, then the group will never be added
> to the vfio container, nor dpdk memory will be ever
> mapped.
> 
> This patch moves the proper error checks earlier in the
> code to fuly prevent setting up devices in secondary
> processes that weren't setup in the primary process.
> 
> Fixes: 2f4adfad0a69 ("vfio: add multiprocess support")
> 

Hi Dariusz,

Thanks for indicating it should be backported. I had picked it directly
from dpdk master also.
https://git.dpdk.org/dpdk-stable/commit/?h=18.08&id=2de3da91ce9120561965583a962fd1fad3793916

Kevin.

> Change-Id: I9ea4dfa7522fd6cf144f40db4492645c7e8c8a65
> Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
> Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  drivers/bus/pci/linux/pci_vfio.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
> index 686386d6a..569953666 100644
> --- a/drivers/bus/pci/linux/pci_vfio.c
> +++ b/drivers/bus/pci/linux/pci_vfio.c
> @@ -551,11 +551,6 @@ pci_vfio_map_resource_secondary(struct rte_pci_device *dev)
>  	snprintf(pci_addr, sizeof(pci_addr), PCI_PRI_FMT,
>  			loc->domain, loc->bus, loc->devid, loc->function);
>  
> -	ret = rte_vfio_setup_device(rte_pci_get_sysfs_path(), pci_addr,
> -					&vfio_dev_fd, &device_info);
> -	if (ret)
> -		return ret;
> -
>  	/* if we're in a secondary process, just find our tailq entry */
>  	TAILQ_FOREACH(vfio_res, vfio_res_list, next) {
>  		if (rte_pci_addr_cmp(&vfio_res->pci_addr,
> @@ -567,9 +562,14 @@ pci_vfio_map_resource_secondary(struct rte_pci_device *dev)
>  	if (vfio_res == NULL) {
>  		RTE_LOG(ERR, EAL, "  %s cannot find TAILQ entry for PCI device!\n",
>  				pci_addr);
> -		goto err_vfio_dev_fd;
> +		return -1;
>  	}
>  
> +	ret = rte_vfio_setup_device(rte_pci_get_sysfs_path(), pci_addr,
> +					&vfio_dev_fd, &device_info);
> +	if (ret)
> +		return ret;
> +
>  	/* map BARs */
>  	maps = vfio_res->maps;
>  
>