Re: [PATCH 1/2 V3] PCI: introduce device assignment interface and refactory related code

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 2014-07-11 at 07:13 -0600, Alex Williamson wrote:
> On Fri, 2014-07-11 at 20:30 +0800, Ethan Zhao wrote:
> > This patch introduces two new device assignment functions
> > 
> > pci_iov_assign_device(),
> > pci_iov_deassign_device()
> > 
> > along with the existed one
> > 
> > pci_vfs_assigned()
> > 
> > They construct the VFs assignment management interface, used to assign/
> > deassign device to VM and query the VFs reference counter. instead of
> > direct manipulation of device flag.
> > 
> > This patch refashioned the related code and make them atomic.
> > 
> > v3: change the naming of device assignment helpers, because they work
> > for all kind of PCI device, not only SR-IOV (david.vrabel@citrix.com)
> > 
> > v2: reorder the patchset and make it bisectable and atomic, steps clear
> > between interface defination and implemenation according to the
> > suggestion from alex.williamson@redhat.com
> > 
> > Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
> > ---
> 
> - Use a cover patch to describe the series
> 
> - Version information goes here, below the "---", not above it
> 
> - I stand by the patch breakdown I suggested originally, there are too
> many logical changes here in patch 1.  There are easily 3 separate
> patches here.
> 
> - Renaming s/sriov/iov/ doesn't address the problem David raised.  The
> name is still synonymous with SR-IOV and it's defined on
> drivers/pci/iov.c, which is only built with CONFIG_PCI_IOV.
> 
> - PCI_DEV_FLAGS_ASSIGNED should be unused after this series, why is it
> not removed?

I guess it's still used, which is even worse because now we have
separate data elements, one tracking how many VFs are assigned from a PF
and another tracking each device that's assigned.  What are we actually
gaining or fixing by doing this?

> >  drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c |   17 ++---------------
> >  drivers/pci/iov.c                                  |   20 ++++++++++++++++++++
> >  drivers/xen/xen-pciback/pci_stub.c                 |    4 ++--
> >  include/linux/pci.h                                |    4 ++++
> >  virt/kvm/assigned-dev.c                            |    2 +-
> >  virt/kvm/iommu.c                                   |    4 ++--
> 
> - This patch touch 4 separate logical code areas, who do you expect to
> ack and commit it?  Split it up.
> 
> >  6 files changed, 31 insertions(+), 20 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> > index 02c11a7..781040e 100644
> > --- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> > @@ -693,22 +693,9 @@ complete_reset:
> >  static bool i40e_vfs_are_assigned(struct i40e_pf *pf)
> >  {
> >  	struct pci_dev *pdev = pf->pdev;
> > -	struct pci_dev *vfdev;
> > -
> > -	/* loop through all the VFs to see if we own any that are assigned */
> > -	vfdev = pci_get_device(PCI_VENDOR_ID_INTEL, I40E_DEV_ID_VF , NULL);
> > -	while (vfdev) {
> > -		/* if we don't own it we don't care */
> > -		if (vfdev->is_virtfn && pci_physfn(vfdev) == pdev) {
> > -			/* if it is assigned we cannot release it */
> > -			if (vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED)
> > -				return true;
> > -		}
> >  
> > -		vfdev = pci_get_device(PCI_VENDOR_ID_INTEL,
> > -				       I40E_DEV_ID_VF,
> > -				       vfdev);
> > -	}
> > +	if (pci_vfs_assigned(pdev))
> > +		return true;
> >  
> >  	return false;
> >  }
> > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> > index de7a747..090f827 100644
> > --- a/drivers/pci/iov.c
> > +++ b/drivers/pci/iov.c
> > @@ -644,6 +644,26 @@ int pci_vfs_assigned(struct pci_dev *dev)
> >  EXPORT_SYMBOL_GPL(pci_vfs_assigned);
> >  
> >  /**
> > + * pci_iov_assign_device - assign device to VM
> > + * @pdev: the device to be assigned.
> > + */
> > +void pci_iov_assign_device(struct pci_dev *pdev)
> > +{
> > +	pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
> > +}
> > +EXPORT_SYMBOL_GPL(pci_iov_assign_device);
> > +
> > +/**
> > + * pci_iov_deassign_device - deasign device from VM
> > + * @pdev: the device to be deassigned.
> > + */
> > +void pci_iov_deassign_device(struct pci_dev *pdev)
> > +{
> > +	pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
> > +}
> > +EXPORT_SYMBOL_GPL(pci_iov_deassign_device);
> > +
> > +/**
> >   * pci_sriov_set_totalvfs -- reduce the TotalVFs available
> >   * @dev: the PCI PF device
> >   * @numvfs: number that should be used for TotalVFs supported
> > diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
> > index 62fcd48..27e00d1 100644
> > --- a/drivers/xen/xen-pciback/pci_stub.c
> > +++ b/drivers/xen/xen-pciback/pci_stub.c
> > @@ -133,7 +133,7 @@ static void pcistub_device_release(struct kref *kref)
> >  	xen_pcibk_config_free_dyn_fields(dev);
> >  	xen_pcibk_config_free_dev(dev);
> >  
> > -	dev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
> > +	pci_iov_deassign_device(dev);
> >  	pci_dev_put(dev);
> >  
> >  	kfree(psdev);
> > @@ -404,7 +404,7 @@ static int pcistub_init_device(struct pci_dev *dev)
> >  	dev_dbg(&dev->dev, "reset device\n");
> >  	xen_pcibk_reset_device(dev);
> >  
> > -	dev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
> > +	pci_iov_assign_device(dev);
> >  	return 0;
> >  
> >  config_release:
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index aab57b4..5ece6d6 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -1603,6 +1603,8 @@ int pci_num_vf(struct pci_dev *dev);
> >  int pci_vfs_assigned(struct pci_dev *dev);
> >  int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs);
> >  int pci_sriov_get_totalvfs(struct pci_dev *dev);
> > +void pci_iov_assign_device(struct pci_dev *dev);
> > +void pci_iov_deassign_device(struct pci_dev *dev);
> >  #else
> >  static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
> >  { return -ENODEV; }
> > @@ -1614,6 +1616,8 @@ static inline int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
> >  { return 0; }
> >  static inline int pci_sriov_get_totalvfs(struct pci_dev *dev)
> >  { return 0; }
> > +static inline void pci_iov_assign_device(struct pci_dev *dev) { }
> > +static inline void pci_iov_deassign_device(struct pci_dev *dev) { }
> >  #endif
> >  
> >  #if defined(CONFIG_HOTPLUG_PCI) || defined(CONFIG_HOTPLUG_PCI_MODULE)
> > diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
> > index bf06577..7fac58d 100644
> > --- a/virt/kvm/assigned-dev.c
> > +++ b/virt/kvm/assigned-dev.c
> > @@ -302,7 +302,7 @@ static void kvm_free_assigned_device(struct kvm *kvm,
> >  	else
> >  		pci_restore_state(assigned_dev->dev);
> >  
> > -	assigned_dev->dev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
> > +	pci_iov_deassign_device(assigned_dev->dev);
> >  
> >  	pci_release_regions(assigned_dev->dev);
> >  	pci_disable_device(assigned_dev->dev);
> > diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
> > index 0df7d4b..641ee73 100644
> > --- a/virt/kvm/iommu.c
> > +++ b/virt/kvm/iommu.c
> > @@ -194,7 +194,7 @@ int kvm_assign_device(struct kvm *kvm,
> >  			goto out_unmap;
> >  	}
> >  
> > -	pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
> > +	pci_iov_assign_device(pdev);
> >  
> >  	dev_info(&pdev->dev, "kvm assign device\n");
> >  
> > @@ -220,7 +220,7 @@ int kvm_deassign_device(struct kvm *kvm,
> >  
> >  	iommu_detach_device(domain, &pdev->dev);
> >  
> > -	pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
> > +	pci_iov_deassign_device(pdev);
> >  
> >  	dev_info(&pdev->dev, "kvm deassign device\n");
> >  
> 
>