[v2,1/2] raw/ioat: add pci address handling to python script

  Currently the user needs to find the DSA instance number for any DSA device
they would like to configure using this script, which can be cumbersome and
error-prone since the instance numbering changes when changing the binding
of the devices between vfio-pci and idxd.

This patch improved the usability of the script by adding the ability to
specify the DSA device to configure using the device's PCI address instead
of the DSA instance number. For example, "$dpdk_idxd_cfg.py 0" and
"$dpdk_idxd_cfg.py 6a:01.0" are both valid references to the same device
(assuming the numbering).

Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>

---
v2:
   - split the device reset change into its own patch
   - changed sysfs dir search
   - improved error case handling
---
 drivers/raw/ioat/dpdk_idxd_cfg.py | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)
  

On Fri, May 28, 2021 at 02:19:01PM +0100, Kevin Laatz wrote:
> Currently the user needs to find the DSA instance number for any DSA device
> they would like to configure using this script, which can be cumbersome and
> error-prone since the instance numbering changes when changing the binding
> of the devices between vfio-pci and idxd.
> 
s/changes/may change/
I've found a number of times that after unbinding and rebinding a device the
number did not change.

> This patch improved the usability of the script by adding the ability to
s/improved/improves/

> specify the DSA device to configure using the device's PCI address instead
> of the DSA instance number. For example, "$dpdk_idxd_cfg.py 0" and
> "$dpdk_idxd_cfg.py 6a:01.0" are both valid references to the same device
> (assuming the numbering).
> 
> Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
> 
With the above minor commit-log tweaks

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

> ---
> v2:
>    - split the device reset change into its own patch
>    - changed sysfs dir search
>    - improved error case handling
> ---
>  drivers/raw/ioat/dpdk_idxd_cfg.py | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/raw/ioat/dpdk_idxd_cfg.py b/drivers/raw/ioat/dpdk_idxd_cfg.py
> index ff06d9e240..ad8393a645 100755
> --- a/drivers/raw/ioat/dpdk_idxd_cfg.py
> +++ b/drivers/raw/ioat/dpdk_idxd_cfg.py
> @@ -29,6 +29,26 @@ def write_values(self, values):
>                  f.write(str(contents))
>  
>  
> +def get_pci_dir(pci):
> +    "Search for the sysfs directory of the PCI device"
> +    base_dir = '/sys/bus/pci/devices/'
> +    for path, dirs, files in os.walk(base_dir):
> +        for dir in dirs:
> +            if pci in dir:
> +                return os.path.join(base_dir, dir)
> +    sys.exit(f"Could not find sysfs directory for device {pci}")
> +
> +
> +def get_dsa_id(pci):
> +    "Get the DSA instance ID using the PCI address of the device"
> +    pci_dir = get_pci_dir(pci)
> +    for path, dirs, files in os.walk(pci_dir):
> +        for dir in dirs:
> +            if dir.startswith('dsa') and 'wq' not in dir:
> +                return int(dir[3:])
> +    sys.exit(f"Could not get device ID for device {pci}")
> +
> +
>  def configure_dsa(dsa_id, queues, prefix):
>      "Configure the DSA instance with appropriate number of queues"
>      dsa_dir = SysfsDir(f"/sys/bus/dsa/devices/dsa{dsa_id}")
> @@ -68,14 +88,18 @@ def main(args):
>      "Main function, does arg parsing and calls config function"
>      arg_p = argparse.ArgumentParser(
>          description="Configure whole DSA device instance for DPDK use")
> -    arg_p.add_argument('dsa_id', type=int, help="DSA instance number")
> +    arg_p.add_argument('dsa_id',
> +                       help="Specify DSA instance either via DSA instance number or PCI address")
>      arg_p.add_argument('-q', metavar='queues', type=int, default=255,
>                         help="Number of queues to set up")
>      arg_p.add_argument('--name-prefix', metavar='prefix', dest='prefix',
>                         default="dpdk",
>                         help="Prefix for workqueue name to mark for DPDK use [default: 'dpdk']")
>      parsed_args = arg_p.parse_args(args[1:])
> -    configure_dsa(parsed_args.dsa_id, parsed_args.q, parsed_args.prefix)
> +
> +    dsa_id = parsed_args.dsa_id
> +    dsa_id = get_dsa_id(dsa_id) if ':' in dsa_id else dsa_id
> +    configure_dsa(dsa_id, parsed_args.q, parsed_args.prefix)
>  
>  
>  if __name__ == "__main__":
> -- 
> 2.30.2
>