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[PATCH v2] xen/pciback: support driver_override

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  [PATCH v2] xen/pciback: support driver_override Juergen Gross <jgross@suse.com> - 2016-09-02 14:40 +0200
    Re: [PATCH v2] xen/pciback: support driver_override Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-09-08 16:20 +0200
      Re: [PATCH v2] xen/pciback: support driver_override Juergen Gross <jgross@suse.com> - 2016-09-09 08:20 +0200

#1475108 — [PATCH v2] xen/pciback: support driver_override

Support the driver_override scheme introduced with commit 782a985d7af2
("PCI: Introduce new device binding path using pci_dev.driver_override")

As pcistub_probe() is called for all devices (it has to check for a
match based on the slot address rather than device type) it has to
check for driver_override set to "pciback" itself.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2: removed now unused label
---
 drivers/xen/xen-pciback/pci_stub.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 258b7c3..85c28f7 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -25,6 +25,8 @@
 #include "conf_space.h"
 #include "conf_space_quirks.h"
 
+#define PCISTUB_DRIVER_NAME "pciback"
+
 static char *pci_devs_to_hide;
 wait_queue_head_t xen_pcibk_aer_wait_queue;
 /*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops,
@@ -529,16 +531,18 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
 				"don't have a normal (0) or bridge (1) "
 				"header type!\n");
 			err = -ENODEV;
-			goto out;
 		}
 
+	} else if (!dev->driver_override ||
+		   strcmp(dev->driver_override, PCISTUB_DRIVER_NAME))
+		/* Didn't find the device */
+		err = -ENODEV;
+
+	if (!err) {
 		dev_info(&dev->dev, "seizing device\n");
 		err = pcistub_seize(dev);
-	} else
-		/* Didn't find the device */
-		err = -ENODEV;
+	}
 
-out:
 	return err;
 }
 
@@ -945,7 +949,7 @@ static const struct pci_error_handlers xen_pcibk_error_handler = {
 static struct pci_driver xen_pcibk_pci_driver = {
 	/* The name should be xen_pciback, but until the tools are updated
 	 * we will keep it as pciback. */
-	.name = "pciback",
+	.name = PCISTUB_DRIVER_NAME,
 	.id_table = pcistub_ids,
 	.probe = pcistub_probe,
 	.remove = pcistub_remove,
-- 
2.6.6

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#1479266

On 09/02/2016 08:30 AM, Juergen Gross wrote:
> Support the driver_override scheme introduced with commit 782a985d7af2
> ("PCI: Introduce new device binding path using pci_dev.driver_override")
>
> As pcistub_probe() is called for all devices (it has to check for a
> match based on the slot address rather than device type) it has to
> check for driver_override set to "pciback" itself.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> V2: removed now unused label
> ---
>  drivers/xen/xen-pciback/pci_stub.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
> index 258b7c3..85c28f7 100644
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -25,6 +25,8 @@
>  #include "conf_space.h"
>  #include "conf_space_quirks.h"
>  
> +#define PCISTUB_DRIVER_NAME "pciback"
> +
>  static char *pci_devs_to_hide;
>  wait_queue_head_t xen_pcibk_aer_wait_queue;
>  /*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops,
> @@ -529,16 +531,18 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  				"don't have a normal (0) or bridge (1) "
>  				"header type!\n");
>  			err = -ENODEV;
> -			goto out;
>  		}
>  
> +	} else if (!dev->driver_override ||
> +		   strcmp(dev->driver_override, PCISTUB_DRIVER_NAME))
> +		/* Didn't find the device */
> +		err = -ENODEV;
> +
> +	if (!err) {
>  		dev_info(&dev->dev, "seizing device\n");
>  		err = pcistub_seize(dev);
> -	} else
> -		/* Didn't find the device */
> -		err = -ENODEV;
> +	}

Should devices with pciback override be displayed in
/sys/bus/pci/drivers/pciback/slots? If they should then they need to be
either added to pcistub_device_ids or kept on some other list.

Also, do you think checking override might better be done first, before
testing for ID match?

-boris


>  
> -out:
>  	return err;
>  }
>  
> @@ -945,7 +949,7 @@ static const struct pci_error_handlers xen_pcibk_error_handler = {
>  static struct pci_driver xen_pcibk_pci_driver = {
>  	/* The name should be xen_pciback, but until the tools are updated
>  	 * we will keep it as pciback. */
> -	.name = "pciback",
> +	.name = PCISTUB_DRIVER_NAME,
>  	.id_table = pcistub_ids,
>  	.probe = pcistub_probe,
>  	.remove = pcistub_remove,

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#1479675

On 08/09/16 16:10, Boris Ostrovsky wrote:
> On 09/02/2016 08:30 AM, Juergen Gross wrote:
>> Support the driver_override scheme introduced with commit 782a985d7af2
>> ("PCI: Introduce new device binding path using pci_dev.driver_override")
>>
>> As pcistub_probe() is called for all devices (it has to check for a
>> match based on the slot address rather than device type) it has to
>> check for driver_override set to "pciback" itself.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>> V2: removed now unused label
>> ---
>>  drivers/xen/xen-pciback/pci_stub.c | 16 ++++++++++------
>>  1 file changed, 10 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
>> index 258b7c3..85c28f7 100644
>> --- a/drivers/xen/xen-pciback/pci_stub.c
>> +++ b/drivers/xen/xen-pciback/pci_stub.c
>> @@ -25,6 +25,8 @@
>>  #include "conf_space.h"
>>  #include "conf_space_quirks.h"
>>  
>> +#define PCISTUB_DRIVER_NAME "pciback"
>> +
>>  static char *pci_devs_to_hide;
>>  wait_queue_head_t xen_pcibk_aer_wait_queue;
>>  /*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops,
>> @@ -529,16 +531,18 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
>>  				"don't have a normal (0) or bridge (1) "
>>  				"header type!\n");
>>  			err = -ENODEV;
>> -			goto out;
>>  		}
>>  
>> +	} else if (!dev->driver_override ||
>> +		   strcmp(dev->driver_override, PCISTUB_DRIVER_NAME))
>> +		/* Didn't find the device */
>> +		err = -ENODEV;
>> +
>> +	if (!err) {
>>  		dev_info(&dev->dev, "seizing device\n");
>>  		err = pcistub_seize(dev);
>> -	} else
>> -		/* Didn't find the device */
>> -		err = -ENODEV;
>> +	}
> 
> Should devices with pciback override be displayed in
> /sys/bus/pci/drivers/pciback/slots? If they should then they need to be
> either added to pcistub_device_ids or kept on some other list.

No, I don't think so. The patch is just needed to _avoid_ having to use
the slots stuff: without the patch you need something like:

echo 0000:07:10.0 > /sys/bus/pci/devices/0000\:07\:10.0/driver/unbind
echo 0000:07:10.0 > /sys/bus/pci/drivers/pciback/new_slot
echo 0000:07:10.0 > /sys/bus/pci/drivers_probe

while with the patch you can use the same mechanism as for similar
drivers like pci-stub and vfio-pci:

echo pciback > /sys/bus/pci/devices/0000\:07\:10.0/driver_override
echo 0000:07:10.0 > /sys/bus/pci/devices/0000\:07\:10.0/driver/unbind
echo 0000:07:10.0 > /sys/bus/pci/drivers_probe

So e.g. libvirt doesn't need special handling for pciback. The slot list
is necessary for assigning devices to pciback on boot, but I think the
override mechanism is better for runtime assignment.

> Also, do you think checking override might better be done first, before
> testing for ID match?

Why? I don't think this really matters.


Juergen

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