Comment 6 for bug 754591

I found this problem, too. A VM used a NIC with PCI-passthrough mode. Then I shutdown the VM, and tried to give the NIC back to the host. But I found I couldn't assign the NIC to the host again. This problem didn't occur each time. If I did this steps for ten times, I could see it at least once.

The kernel version was 2.6.32. I used Intel e1000e driver for the NIC. Here are some of the logs:
kernel: e1000e 0000:02:00.1: enabling device (0000 -> 0002)
kernel: e1000e 0000:02:00.1: PCI INT B -> GSI 17 (level, low) -> IRQ 17
kernel: 0000:02:00.1: 0000:02:00.1: PHY reset is blocked due to SOL/IDER session.
kernel: 0000:02:00.1: 0000:02:00.1: The NVM Checksum Is Not Valid
 kernel: e1000e 0000:02:00.1: PCI INT B disabled