s390x/pci: drive ISM reset from subsystem reset

s390x/pci: drive ISM reset from subsystem reset

ISM devices are sensitive to manipulation of the IOMMU, so the ISM device
needs to be reset before the vfio-pci device is reset (triggering a full
UNMAP).  In order to ensure this occurs, trigger ISM device resets from
subsystem_reset before triggering the PCI bus reset (which will also
trigger vfio-pci reset).  This only needs to be done for ISM devices
which were enabled for use by the guest.
Further, ensure that AIF is disabled as part of the reset event.

Fixes: ef1535901a ("s390x: do a subsystem reset before the unprotect on reboot")
Fixes: 03451953c7 ("s390x/pci: reset ISM passthrough devices on shutdown and system reset")
Reported-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Message-ID: <20240118185151.265329-4-mjrosato@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>