Re: [RFC PATCH v1 2/2] vfio: Add VFIO API vfio_msi_get_irq

[Eric Auger <eric.auger@linaro.org>]

On 11/20/2014 05:05 PM, Alex Williamson wrote:
> On Thu, 2014-11-20 at 17:05 +0800, Feng Wu wrote:
>> This API returns the host irq for the MSI/MSI-X interrrupts.
>>
>> Signed-off-by: Feng Wu <feng.wu@intel.com>
>> ---
>>  drivers/vfio/pci/vfio_pci.c |   10 ++++++++++
>>  include/linux/vfio.h        |    2 ++
>>  2 files changed, 12 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
>> index 9558da3..4fb9828 100644
>> --- a/drivers/vfio/pci/vfio_pci.c
>> +++ b/drivers/vfio/pci/vfio_pci.c
>> @@ -1009,6 +1009,16 @@ put_devs:
>>  	kfree(devs.devices);
>>  }
>>  
>> +unsigned int vfio_msi_get_irq(struct vfio_device *device, int vector, bool msix)
>> +{
>> +	struct vfio_pci_device *vdev =
>> +			(struct vfio_pci_device *)vfio_device_data(device);
>> +	struct pci_dev *pdev = vdev->pdev;
>> +
>> +	return msix ? vdev->msix[vector].vector : pdev->irq + vector;
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_msi_get_irq);
>> +
> 
> It's difficult to see what you're going to do with this, but it's making
> the assumption that the vfio_device is a vfio_pci_device, which is the
> wrong starting point.  Eric proposed[1] some VFIO external user
> interface extensions, that have since been refined in discussion that
> allows the external user (KVM in this case) access to the struct device
> where it can get the IRQ vectors itself.  We either need to follow that
> same path for posted interrupts, teaching KVM about struct pci_device in
> order to extract the IRQ info, or we need to create another vfio
> external user interface extension that can return IRQ info regardless of
> the device type.  Thanks,
> 
> Alex
> 
> 
> [1] https://lkml.org/lkml/2014/8/25/257

Here is the v2: https://lkml.org/lkml/2014/9/1/347

Best Regards

Eric
> http://lwn.net/Articles/610087/
>>  static void __exit vfio_pci_cleanup(void)
>>  {
>>  	pci_unregister_driver(&vfio_pci_driver);
>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>> index d320411..007ca55 100644
>> --- a/include/linux/vfio.h
>> +++ b/include/linux/vfio.h
>> @@ -92,6 +92,8 @@ extern void vfio_unregister_iommu_driver(
>>  /*
>>   * External user API
>>   */
>> +extern unsigned int vfio_msi_get_irq(struct vfio_device *device, int vector,
>> +				      bool msix);
>>  extern struct vfio_group *vfio_group_get_external_user(struct file *filep);
>>  extern void vfio_group_put_external_user(struct vfio_group *group);
>>  extern int vfio_external_user_iommu_id(struct vfio_group *group);
> 
> 
>