cloud-hypervisor/vmm
Sebastien Boeuf 7cbd47a71a vmm: Prevent KVM device fd from being unusable from VfioContainer
When shutting down a VM using VFIO, the following error has been
detected:

vfio-ioctls/src/vfio_device.rs:312 -- Could not delete VFIO group:
KvmSetDeviceAttr(Error(9))

After some investigation, it appears the KVM device file descriptor used
for removing a VFIO group was already closed. This is coming from the
Rust sequence of Drop, from the DeviceManager all the way down to
VfioDevice.

Because the DeviceManager owns passthrough_device, which is effectively
a KVM device file descriptor, when the DeviceManager is dropped, the
passthrough_device follows, with the effect of closing the KVM device
file descriptor. Problem is, VfioDevice has not been dropped yet and it
still needs a valid KVM device file descriptor.

That's why the simple way to fix this issue coming from Rust dropping
all resources is to make Linux accountable for it by duplicating the
file descriptor. This way, even when the passthrough_device is dropped,
the KVM file descriptor is closed, but a duplicated instance is still
valid and owned by the VfioContainer.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
2020-10-15 19:15:28 +02:00
..
src vmm: Prevent KVM device fd from being unusable from VfioContainer 2020-10-15 19:15:28 +02:00
Cargo.toml build(deps): bump libc from 0.2.78 to 0.2.79 2020-10-05 07:02:05 +00:00