From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:54716 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751086AbaKKTJe (ORCPT ); Tue, 11 Nov 2014 14:09:34 -0500 Message-ID: <54625EE8.1050509@redhat.com> Date: Tue, 11 Nov 2014 14:09:28 -0500 From: Don Dutile MIME-Version: 1.0 To: Sathya Perla , linux-pci@vger.kernel.org, netdev@vger.kernel.org CC: ariel.elior@qlogic.com, linux.nics@intel.com, shahed.shaikh@qlogic.com Subject: Re: [PATCH 0/4] move pci_assivned_vfs() check (while disabling VFs) to pci sub-system References: <1415620410-4937-1-git-send-email-sathya.perla@emulex.com> In-Reply-To: <1415620410-4937-1-git-send-email-sathya.perla@emulex.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: 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.