The vfio_ap_mdev_hot_unplug_cfg() function uses the return value of bitmap_andnot() to determine whether the guest APCB needs to be updated. However, bitmap_andnot() returns false when the resulting destination bitmap is empty. This means that if the only adapter, domain or control domain assigned to an mdev is removed from the host's AP configuration, the bit is correctly cleared from the shadow APCB, but bitmap_andnot() returns false because the result is an empty bitmap. Consequently, do_hotplug remains 0 and vfio_ap_mdev_update_guest_apcb() is never called, leaving the KVM guest with stale hardware access to the unplugged AP devices. Fix this by replacing the bitmap_andnot() return value check with bitmap_intersects() to determine whether the shadow APCB actually overlaps with the removal mask. If there is an intersection, call bitmap_andnot() solely for its side effect of clearing the bits, then unconditionally set do_hotplug to trigger the guest APCB update. Fixes: eeb386aeb5b7c ("s390/vfio-ap: handle config changed and scan complete notification") Cc: stable@vger.kernel.org Signed-off-by: Anthony Krowiak Reviewed-by: Matthew Rosato --- drivers/s390/crypto/vfio_ap_ops.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index cdc9bf5c5e53..cb1e5db69d8a 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -2563,24 +2563,28 @@ static void vfio_ap_mdev_hot_unplug_cfg(struct ap_matrix_mdev *matrix_mdev, unsigned long *aqrem, unsigned long *cdrem) { - int do_hotplug = 0; + bool do_hotplug = false; - if (!bitmap_empty(aprem, AP_DEVICES)) { - do_hotplug |= bitmap_andnot(matrix_mdev->shadow_apcb.apm, - matrix_mdev->shadow_apcb.apm, - aprem, AP_DEVICES); + if (bitmap_intersects(matrix_mdev->shadow_apcb.apm, aprem, AP_DEVICES)) { + bitmap_andnot(matrix_mdev->shadow_apcb.apm, + matrix_mdev->shadow_apcb.apm, + aprem, AP_DEVICES); + do_hotplug = true; } - if (!bitmap_empty(aqrem, AP_DOMAINS)) { - do_hotplug |= bitmap_andnot(matrix_mdev->shadow_apcb.aqm, - matrix_mdev->shadow_apcb.aqm, - aqrem, AP_DEVICES); + if (bitmap_intersects(matrix_mdev->shadow_apcb.aqm, aqrem, AP_DOMAINS)) { + bitmap_andnot(matrix_mdev->shadow_apcb.aqm, + matrix_mdev->shadow_apcb.aqm, + aqrem, AP_DOMAINS); + do_hotplug = true; } - if (!bitmap_empty(cdrem, AP_DOMAINS)) - do_hotplug |= bitmap_andnot(matrix_mdev->shadow_apcb.adm, - matrix_mdev->shadow_apcb.adm, - cdrem, AP_DOMAINS); + if (bitmap_intersects(matrix_mdev->shadow_apcb.adm, cdrem, AP_DOMAINS)) { + bitmap_andnot(matrix_mdev->shadow_apcb.adm, + matrix_mdev->shadow_apcb.adm, + cdrem, AP_DOMAINS); + do_hotplug = true; + } if (do_hotplug) vfio_ap_mdev_update_guest_apcb(matrix_mdev); -- 2.53.0