[Intel-gfx] [PATCH v3 12/12] vfio/pci: Report dev_id in VFIO_DEVICE_GET_PCI_HOT_RESET_INFO

[Liu, Yi L]

> From: Alex Williamson <alex.williamson at redhat.com>
> Sent: Monday, April 3, 2023 11:02 PM
> 
> On Mon, 3 Apr 2023 09:25:06 +0000
> "Liu, Yi L" <yi.l.liu at intel.com> wrote:
> 
> > > From: Liu, Yi L <yi.l.liu at intel.com>
> > > Sent: Saturday, April 1, 2023 10:44 PM
> >
> > > @@ -791,7 +813,21 @@ static int vfio_pci_fill_devs(struct pci_dev *pdev, void
> *data)
> > >  	if (!iommu_group)
> > >  		return -EPERM; /* Cannot reset non-isolated devices */
> >
> > Hi Alex,
> >
> > Is disabling iommu a sane way to test vfio noiommu mode?
> 
> Yes
> 
> > I added intel_iommu=off to disable intel iommu and bind a device to vfio-pci.
> > I can see the /dev/vfio/noiommu-0 and /dev/vfio/devices/noiommu-vfio0. Bind
> > iommufd==-1 can succeed, but failed to get hot reset info due to the above
> > group check. Reason is that this happens to have some affected devices, and
> > these devices have no valid iommu_group (because they are not bound to vfio-pci
> > hence nobody allocates noiommu group for them). So when hot reset info loops
> > such devices, it failed with -EPERM. Is this expected?
> 
> Hmm, I didn't recall that we put in such a limitation, but given the
> minimally intrusive approach to no-iommu and the fact that we never
> defined an invalid group ID to return to the user, it makes sense that
> we just blocked the ioctl for no-iommu use.  I guess we can do the same
> for no-iommu cdev.

sure.

> 
> BTW, what does this series apply on?  I'm assuming[1], but I don't see
> a branch from Jason yet.  Thanks,

yes, this series is applied on [1]. I put the [1], this series and cdev series
in https://github.com/yiliu1765/iommufd/commits/vfio_device_cdev_v9.

Jason has taken [1] in the below branch. It is based on rc1. So I hesitated
to apply this series and cdev series on top of it. Maybe I should have done
it to make life easier. 😊

https://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd.git/log/?h=for-next

> Alex
> 
> [1]https://lore.kernel.org/all/20230327093351.44505-1-yi.l.liu@intel.com/

Regards,
Yi Liu