> -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > > On Tue, 2014-11-11 at 14:09 -0500, Don Dutile wrote: > > On 11/10/2014 06:53 AM, Sathya Perla wrote: > > > A user must not be allowed to disable VFs while they are already assigned > to > > > a guest. This check is being made in each individual driver that > implements > > > the sriov_configure PCI method. > > > This patch-set fixes this code duplication by moving this check from > > > drivers to the sriov_nuvfs_store() routine just before invoking > > > sriov_configure() when num_vfs is equal to 0. > > > > > > Vasundhara Volam (4): > > > pci: move pci_assivned_vfs() check while disabling VFs to pci > > > sub-system > > > bnx2x: remove pci_assigned_vfs() check while disabling VFs > > > i40e: remove pci_assigned_vfs() check while disabling VFs > > > qlcnic: remove pci_assigned_vfs() check while disabling VFs > > > > > > drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c | 2 +- > > > drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c | 7 +------ > > > .../net/ethernet/qlogic/qlcnic/qlcnic_sriov_pf.c | 10 ---------- > > > drivers/pci/pci-sysfs.c | 5 +++++ > > > 4 files changed, 7 insertions(+), 17 deletions(-) > > > > > I have had a side conversation with Alex Williamson, VFIO author. > > > > VFIO is the upstream method that device-assignment is managed/handled > on kvm now. > > It does not set the PCI_DEV_FLAGS_ASSIGNED pci dev-flags, and thus, > > this check will not work when VFIO is used. > > > > This patch set will only work for the former, kvm-managed, device- > assignment method, > > which is currently being deprecated in qemu as well. > > > > So, yes, it works for kvm managed device-assignment, but not the > > newer, VFIO-based device-assignment. > > > > Note, also, that the pci_assigned_vfs() check in the drivers will > > always return 0 when VFIO is used for device assignment, so keeping > > these checks in the drivers doesn't do what they imply either. > > > > So, taking in the patch solves old, kvm-managed, device assignment, > > but a new method is needed when VFIO is involved. > > > > - Don > > > > ps -- Note: just adding the flag setting in vfio-pci does not necessarily > > solve this problem. VFIO does not know if a device is assigned to a > guest; > > it only knows a caller of the ioctl requesting the device to be assigned > > to vfio, and to be dma-mapped for a region of memory, has been > requested. > > So, a new PF<->VF mechanism needs to be put in place to > > determine the equivalent information. > > pps -- Note: testing pci_assivned_vfs() is racy, nothing prevents the flag > being added to a device between your check and removing the VF > device. > This is one of the reasons that vfio-pci doesn't use it and that this > interface should be discouraged in the kernel. Alex/Don, I agree with the points you've raised. But, I'd like to know whether you think this patch-set should be accepted or not. Even though this patch-set doesn't fix any of the pending issues raised here, it's a small step forward as it reduces the number of invocations of pci_assigned_vfs() check which is a good thing. thanks, -Sathya ��.n��������+%������w��{.n�����{���"�)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
