On 5/31/23 10:48 AM, Matthew Rosato wrote:
On 5/30/23 6:35 PM, Tony Krowiak wrote:
When a user attempts to remove a vfio-ap mediated device attached to a
guest, the operation hangs until the mdev's fd is closed by the guest
(i.e., the hostdev is detached or the guest is shut down). This patch
series provides kernel-side code that allows userspace to set up a
communication channel that will allow the vfio_ap device driver to notify
userspace when a request to release the mdev is received, so that userspace
can close the mdev fd and avoid the hang. The patch series provides the
following:
1. Introduces code to handle the VFIO_DEVICE_GET_IRQ_INFO and
VFIO_DEVICE_SET_IRQS ioctl calls to set the eventfd_ctx for signaling a
device request to userspace.
2. Wires up the VFIO bus driver callback to request a release of the mdev.
When invoked, the vfio_ap device driver will use the eventfd_ctx set up
in #1 to signal a request to userspace to release the mdev.
Note:
----
If a user subsequently attempts to restart the guest or re-attach the mdev,
the operation will fail with a message indicating the domain is already
active. This is a libvirt problem resolved with the following commit:
commit ebd004a03dbd ("security: do not remember/recall labels for VFIO
MDEVs")
For the series:
Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
Thanks for the review.
I also did some testing using the companion qemu series at
https://lore.kernel.org/qemu-devel/20230530225544.280031-1-akrowiak@xxxxxxxxxxxxx
Shall I credit you with Tested-by also?
Before kernel+qemu changes:
1. mdevctl start -u <uuid>, where <uuid> references a vfio-ap mdev
2. start a qemu guest with <uuid> attached
3. mdvectl stop -u <uuid>
4. -mdevctl will now hang indefinitely; the mdev remains in-use by the guest-
Note: detaching the device or powering off the guest will allow the mdevctl command to complete.
After kernel+qemu changes:
1. mdevctl start -u <uuid>, where <uuid> references a vfio-ap mdev
2. start a qemu guest with <uuid> attached
3. mdvectl stop -u <uuid>
4. -device is detached from the guest and stopped-
5. Using a libvirt that includes ebd004a03dbd I also verified that the mdev can be started again and re-attached to the running guest without error.
Tony Krowiak (3):
vfio: ap: realize the VFIO_DEVICE_GET_IRQ_INFO ioctl
vfio: ap: realize the VFIO_DEVICE_SET_IRQS ioctl
s390/vfio-ap: Wire in the vfio_device_ops request callback
drivers/s390/crypto/vfio_ap_ops.c | 134 +++++++++++++++++++++++++-
drivers/s390/crypto/vfio_ap_private.h | 3 +
include/uapi/linux/vfio.h | 9 ++
3 files changed, 145 insertions(+), 1 deletion(-)
