pci: Add flag indicating device has been assigned by KVM

Device drivers that create and destroy SR-IOV virtual functions via
calls to pci_enable_sriov() and pci_disable_sriov can cause catastrophic
failures if they attempt to destroy VFs while they are assigned to
guest virtual machines.  By adding a flag for use by the KVM module
to indicate that a device is assigned a device driver can check that
flag and avoid destroying VFs while they are assigned and avoid system
failures.

CC: Ian Campbell <ijc@hellion.org.uk>
CC: Konrad Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 4e9eaeb518c7..eaf3a50f9769 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -205,6 +205,8 @@ 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_release_regions(assigned_dev->dev);
         pci_disable_device(assigned_dev->dev);
         pci_dev_put(assigned_dev->dev);