[PATCH 1/1] vfio-pci: Add SR-IOV VF configuration via sysfs

[PATCH 1/1] vfio-pci: Add SR-IOV VF configuration via sysfs

[Andre Richter]

If a PCIe device bound to vfio-pci happens to be SR-IOV capabale,
there is no possibility to bring up/shutdown the device's VFs.

This patch adds a generic callback for the sysfs sriov_numvfs attribute.
The attribute will only show up for SR-IOV devices. Additionally,
each utilized pci_* function checks if the device is a PF.

Signed-off-by: Andre Richter <andre.o.richter@gmail.com>
---
 drivers/vfio/pci/vfio_pci.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index f782533..2f6dfb3 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -919,12 +919,27 @@ static struct pci_error_handlers vfio_err_handlers = {
 	.error_detected = vfio_pci_aer_err_detected,
 };
 
+static int vfio_pci_sriov_configure(struct pci_dev *pdev, int num_vfs)
+{
+	int ret = 0;
+
+	if (num_vfs > 0) {
+		ret = pci_enable_sriov(pdev, num_vfs);
+		if (!ret)
+			ret = pci_num_vf(pdev);
+	} else
+		pci_disable_sriov(pdev);
+
+	return ret;
+}
+
 static struct pci_driver vfio_pci_driver = {
-	.name		= "vfio-pci",
-	.id_table	= NULL, /* only dynamic ids */
-	.probe		= vfio_pci_probe,
-	.remove		= vfio_pci_remove,
-	.err_handler	= &vfio_err_handlers,
+	.name			= "vfio-pci",
+	.id_table		= NULL, /* only dynamic ids */
+	.probe			= vfio_pci_probe,
+	.remove			= vfio_pci_remove,
+	.sriov_configure	= vfio_pci_sriov_configure,
+	.err_handler		= &vfio_err_handlers,
 };
 
 /*
-- 
1.9.1

Re: [PATCH 1/1] vfio-pci: Add SR-IOV VF configuration via sysfs

[Alex Williamson]

On Wed, 2014-10-01 at 15:38 +0200, Andre Richter wrote:
> If a PCIe device bound to vfio-pci happens to be SR-IOV capabale,
> there is no possibility to bring up/shutdown the device's VFs.
> 
> This patch adds a generic callback for the sysfs sriov_numvfs attribute.
> The attribute will only show up for SR-IOV devices. Additionally,
> each utilized pci_* function checks if the device is a PF.
> 
> Signed-off-by: Andre Richter <andre.o.richter@gmail.com>
> ---
>  drivers/vfio/pci/vfio_pci.c | 25 ++++++++++++++++++++-----
>  1 file changed, 20 insertions(+), 5 deletions(-)

I don't understand why you'd want to do this.  The PF is typically
managed by a host driver.  By allowing vfio-pci to manage SR-IOV, don't
we potentially have assign-able PFs managing assign-able VFs?  That
seems like a bad idea.  What use case do you have in mind?  Thanks,

Alex

> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index f782533..2f6dfb3 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -919,12 +919,27 @@ static struct pci_error_handlers vfio_err_handlers = {
>  	.error_detected = vfio_pci_aer_err_detected,
>  };
>  
> +static int vfio_pci_sriov_configure(struct pci_dev *pdev, int num_vfs)
> +{
> +	int ret = 0;
> +
> +	if (num_vfs > 0) {
> +		ret = pci_enable_sriov(pdev, num_vfs);
> +		if (!ret)
> +			ret = pci_num_vf(pdev);
> +	} else
> +		pci_disable_sriov(pdev);
> +
> +	return ret;
> +}
> +
>  static struct pci_driver vfio_pci_driver = {
> -	.name		= "vfio-pci",
> -	.id_table	= NULL, /* only dynamic ids */
> -	.probe		= vfio_pci_probe,
> -	.remove		= vfio_pci_remove,
> -	.err_handler	= &vfio_err_handlers,
> +	.name			= "vfio-pci",
> +	.id_table		= NULL, /* only dynamic ids */
> +	.probe			= vfio_pci_probe,
> +	.remove			= vfio_pci_remove,
> +	.sriov_configure	= vfio_pci_sriov_configure,
> +	.err_handler		= &vfio_err_handlers,
>  };
>  
>  /*

Re: [PATCH 1/1] vfio-pci: Add SR-IOV VF configuration via sysfs

[Andre Richter]

I currently use it for early development/debugging work (SR-IOV
capable FPGA boards) where I test both PFs and VFs from userspace.
But I see your point that this may not be relevant for anything you
can buy off the shelf.

Cheers,
Andre

2014-10-01 16:03 GMT+02:00 Alex Williamson <alex.williamson@redhat.com>:
> On Wed, 2014-10-01 at 15:38 +0200, Andre Richter wrote:
>> If a PCIe device bound to vfio-pci happens to be SR-IOV capabale,
>> there is no possibility to bring up/shutdown the device's VFs.
>>
>> This patch adds a generic callback for the sysfs sriov_numvfs attribute.
>> The attribute will only show up for SR-IOV devices. Additionally,
>> each utilized pci_* function checks if the device is a PF.
>>
>> Signed-off-by: Andre Richter <andre.o.richter@gmail.com>
>> ---
>>  drivers/vfio/pci/vfio_pci.c | 25 ++++++++++++++++++++-----
>>  1 file changed, 20 insertions(+), 5 deletions(-)
>
> I don't understand why you'd want to do this.  The PF is typically
> managed by a host driver.  By allowing vfio-pci to manage SR-IOV, don't
> we potentially have assign-able PFs managing assign-able VFs?  That
> seems like a bad idea.  What use case do you have in mind?  Thanks,
>
> Alex
>
>> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
>> index f782533..2f6dfb3 100644
>> --- a/drivers/vfio/pci/vfio_pci.c
>> +++ b/drivers/vfio/pci/vfio_pci.c
>> @@ -919,12 +919,27 @@ static struct pci_error_handlers vfio_err_handlers = {
>>       .error_detected = vfio_pci_aer_err_detected,
>>  };
>>
>> +static int vfio_pci_sriov_configure(struct pci_dev *pdev, int num_vfs)
>> +{
>> +     int ret = 0;
>> +
>> +     if (num_vfs > 0) {
>> +             ret = pci_enable_sriov(pdev, num_vfs);
>> +             if (!ret)
>> +                     ret = pci_num_vf(pdev);
>> +     } else
>> +             pci_disable_sriov(pdev);
>> +
>> +     return ret;
>> +}
>> +
>>  static struct pci_driver vfio_pci_driver = {
>> -     .name           = "vfio-pci",
>> -     .id_table       = NULL, /* only dynamic ids */
>> -     .probe          = vfio_pci_probe,
>> -     .remove         = vfio_pci_remove,
>> -     .err_handler    = &vfio_err_handlers,
>> +     .name                   = "vfio-pci",
>> +     .id_table               = NULL, /* only dynamic ids */
>> +     .probe                  = vfio_pci_probe,
>> +     .remove                 = vfio_pci_remove,
>> +     .sriov_configure        = vfio_pci_sriov_configure,
>> +     .err_handler            = &vfio_err_handlers,
>>  };
>>
>>  /*
>
>
>

Re: [PATCH 1/1] vfio-pci: Add SR-IOV VF configuration via sysfs

[Alex Williamson]

On Wed, 2014-10-01 at 16:28 +0200, Andre Richter wrote:
> I currently use it for early development/debugging work (SR-IOV
> capable FPGA boards) where I test both PFs and VFs from userspace.
> But I see your point that this may not be relevant for anything you
> can buy off the shelf.

What about adding the same to pci-stub?  At least that way the PF can't
actually be assigned to a guest via vfio.  Legacy KVM assignment would
still allow it, but then legacy KVM assignment will attempt to assign a
device regardless of the host driver.  BTW, I'd expect there also needs
to be a call to pci_disable_sriov() in the driver release function.
Thanks,

Alex

> 2014-10-01 16:03 GMT+02:00 Alex Williamson <alex.williamson@redhat.com>:
> > On Wed, 2014-10-01 at 15:38 +0200, Andre Richter wrote:
> >> If a PCIe device bound to vfio-pci happens to be SR-IOV capabale,
> >> there is no possibility to bring up/shutdown the device's VFs.
> >>
> >> This patch adds a generic callback for the sysfs sriov_numvfs attribute.
> >> The attribute will only show up for SR-IOV devices. Additionally,
> >> each utilized pci_* function checks if the device is a PF.
> >>
> >> Signed-off-by: Andre Richter <andre.o.richter@gmail.com>
> >> ---
> >>  drivers/vfio/pci/vfio_pci.c | 25 ++++++++++++++++++++-----
> >>  1 file changed, 20 insertions(+), 5 deletions(-)
> >
> > I don't understand why you'd want to do this.  The PF is typically
> > managed by a host driver.  By allowing vfio-pci to manage SR-IOV, don't
> > we potentially have assign-able PFs managing assign-able VFs?  That
> > seems like a bad idea.  What use case do you have in mind?  Thanks,
> >
> > Alex
> >
> >> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> >> index f782533..2f6dfb3 100644
> >> --- a/drivers/vfio/pci/vfio_pci.c
> >> +++ b/drivers/vfio/pci/vfio_pci.c
> >> @@ -919,12 +919,27 @@ static struct pci_error_handlers vfio_err_handlers = {
> >>       .error_detected = vfio_pci_aer_err_detected,
> >>  };
> >>
> >> +static int vfio_pci_sriov_configure(struct pci_dev *pdev, int num_vfs)
> >> +{
> >> +     int ret = 0;
> >> +
> >> +     if (num_vfs > 0) {
> >> +             ret = pci_enable_sriov(pdev, num_vfs);
> >> +             if (!ret)
> >> +                     ret = pci_num_vf(pdev);
> >> +     } else
> >> +             pci_disable_sriov(pdev);
> >> +
> >> +     return ret;
> >> +}
> >> +
> >>  static struct pci_driver vfio_pci_driver = {
> >> -     .name           = "vfio-pci",
> >> -     .id_table       = NULL, /* only dynamic ids */
> >> -     .probe          = vfio_pci_probe,
> >> -     .remove         = vfio_pci_remove,
> >> -     .err_handler    = &vfio_err_handlers,
> >> +     .name                   = "vfio-pci",
> >> +     .id_table               = NULL, /* only dynamic ids */
> >> +     .probe                  = vfio_pci_probe,
> >> +     .remove                 = vfio_pci_remove,
> >> +     .sriov_configure        = vfio_pci_sriov_configure,
> >> +     .err_handler            = &vfio_err_handlers,
> >>  };
> >>
> >>  /*
> >
> >
> >