Messages in this thread | | | Date | Thu, 1 Jun 2023 08:15:27 -0400 | Subject | Re: [PATCH 0/3] s390/vfio-ap: fix hang when mdev attached to guest is removed | From | Anthony Krowiak <> |
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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@linux.ibm.com>
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@linux.ibm.com
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(-) >> >
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