This is a note to let you know that I've just added the patch titled
s390/vfio-ap: let on_scan_complete() callback filter matrix and update guest's APCB
to the 6.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-vfio-ap-let-on_scan_complete-callback-filter-matrix-and-update-guest-s-apcb.patch
and it can be found in the queue-6.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 774d10196e648e2c0b78da817f631edfb3dfa557 Mon Sep 17 00:00:00 2001
From: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Date: Mon, 15 Jan 2024 13:54:33 -0500
Subject: s390/vfio-ap: let on_scan_complete() callback filter matrix and update guest's APCB
From: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
commit 774d10196e648e2c0b78da817f631edfb3dfa557 upstream.
When adapters and/or domains are added to the host's AP configuration, this
may result in multiple queue devices getting created and probed by the
vfio_ap device driver. For each queue device probed, the matrix of adapters
and domains assigned to a matrix mdev will be filtered to update the
guest's APCB. If any adapters or domains get added to or removed from the
APCB, the guest's AP configuration will be dynamically updated (i.e., hot
plug/unplug). To dynamically update the guest's configuration, its VCPUs
must be taken out of SIE for the period of time it takes to make the
update. This is disruptive to the guest's operation and if there are many
queues probed due to a change in the host's AP configuration, this could be
troublesome. The problem is exacerbated by the fact that the
'on_scan_complete' callback also filters the mdev's matrix and updates
the guest's AP configuration.
In order to reduce the potential amount of disruption to the guest that may
result from a change to the host's AP configuration, let's bypass the
filtering of the matrix and updating of the guest's AP configuration in the
probe callback - if due to a host config change - and defer it until the
'on_scan_complete' callback is invoked after the AP bus finishes its device
scan operation. This way the filtering and updating will be performed only
once regardless of the number of queues added.
Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
Fixes: 48cae940c31d ("s390/vfio-ap: refresh guest's APCB by filtering AP resources assigned to mdev")
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20240115185441.31526-4-akrowiak@xxxxxxxxxxxxx
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/s390/crypto/vfio_ap_ops.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -2084,9 +2084,22 @@ int vfio_ap_mdev_probe_queue(struct ap_d
if (matrix_mdev) {
vfio_ap_mdev_link_queue(matrix_mdev, q);
+ /*
+ * If we're in the process of handling the adding of adapters or
+ * domains to the host's AP configuration, then let the
+ * vfio_ap device driver's on_scan_complete callback filter the
+ * matrix and update the guest's AP configuration after all of
+ * the new queue devices are probed.
+ */
+ if (!bitmap_empty(matrix_mdev->apm_add, AP_DEVICES) ||
+ !bitmap_empty(matrix_mdev->aqm_add, AP_DOMAINS))
+ goto done;
+
if (vfio_ap_mdev_filter_matrix(matrix_mdev))
vfio_ap_mdev_update_guest_apcb(matrix_mdev);
}
+
+done:
dev_set_drvdata(&apdev->device, q);
release_update_locks_for_mdev(matrix_mdev);
Patches currently in stable-queue which might be from akrowiak@xxxxxxxxxxxxx are
queue-6.7/s390-vfio-ap-loop-over-the-shadow-apcb-when-filtering-guest-s-ap-configuration.patch
queue-6.7/s390-vfio-ap-reset-queues-associated-with-adapter-for-queue-unbound-from-driver.patch
queue-6.7/s390-vfio-ap-let-on_scan_complete-callback-filter-matrix-and-update-guest-s-apcb.patch
queue-6.7/s390-vfio-ap-do-not-reset-queue-removed-from-host-config.patch
queue-6.7/s390-vfio-ap-reset-queues-filtered-from-the-guest-s-ap-config.patch
queue-6.7/s390-vfio-ap-always-filter-entire-ap-matrix.patch
queue-6.7/s390-vfio-ap-unpin-pages-on-gisc-registration-failure.patch
