Re: [PATCH v2 3/3] s390x/pci: drive ISM reset from subsystem reset

[Eric Farman]

On Thu, 2024-01-18 at 13:51 -0500, Matthew Rosato wrote:
> 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>
> ---
>  hw/s390x/s390-pci-bus.c         | 26 +++++++++++++++++---------
>  hw/s390x/s390-virtio-ccw.c      |  8 ++++++++
>  include/hw/s390x/s390-pci-bus.h |  1 +
>  3 files changed, 26 insertions(+), 9 deletions(-)

Thanks for the reminder on ISM/interpretation in v1.

Reviewed-by: Eric Farman <farman@linux.ibm.com>