Pull VFIO updates from Alex Williamson:
- Replace deprecated git://github.com link in MAINTAINERS (Palmer
Dabbelt)
- Simplify vfio/mlx5 with module_pci_driver() helper (Shang XiaoJing)
- Drop unnecessary buffer from ACPI call (Rafael Mendonca)
- Correct latent missing include issue in iova-bitmap and fix support
for unaligned bitmaps. Follow-up with better fix through refactor
(Joao Martins)
- Rework ccw mdev driver to split private data from parent structure,
better aligning with the mdev lifecycle and allowing us to remove a
temporary workaround (Eric Farman)
- Add an interface to get an estimated migration data size for a
device, allowing userspace to make informed decisions, ex. more
accurately predicting VM downtime (Yishai Hadas)
- Fix minor typo in vfio/mlx5 array declaration (Yishai Hadas)
- Simplify module and Kconfig through consolidating SPAPR/EEH code and
config options and folding virqfd module into main vfio module (Jason
Gunthorpe)
- Fix error path from device_register() across all vfio mdev and sample
drivers (Alex Williamson)
- Define migration pre-copy interface and implement for vfio/mlx5
devices, allowing portions of the device state to be saved while the
device continues operation, towards reducing the stop-copy state size
(Jason Gunthorpe, Yishai Hadas, Shay Drory)
- Implement pre-copy for hisi_acc devices (Shameer Kolothum)
- Fixes to mdpy mdev driver remove path and error path on probe (Shang
XiaoJing)
- vfio/mlx5 fixes for incorrect return after copy_to_user() fault and
incorrect buffer freeing (Dan Carpenter)
* tag 'vfio-v6.2-rc1' of https://github.com/awilliam/linux-vfio: (42 commits)
vfio/mlx5: error pointer dereference in error handling
vfio/mlx5: fix error code in mlx5vf_precopy_ioctl()
samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe()
hisi_acc_vfio_pci: Enable PRE_COPY flag
hisi_acc_vfio_pci: Move the dev compatibility tests for early check
hisi_acc_vfio_pci: Introduce support for PRE_COPY state transitions
hisi_acc_vfio_pci: Add support for precopy IOCTL
vfio/mlx5: Enable MIGRATION_PRE_COPY flag
vfio/mlx5: Fallback to STOP_COPY upon specific PRE_COPY error
vfio/mlx5: Introduce multiple loads
vfio/mlx5: Consider temporary end of stream as part of PRE_COPY
vfio/mlx5: Introduce vfio precopy ioctl implementation
vfio/mlx5: Introduce SW headers for migration states
vfio/mlx5: Introduce device transitions of PRE_COPY
vfio/mlx5: Refactor to use queue based data chunks
vfio/mlx5: Refactor migration file state
vfio/mlx5: Refactor MKEY usage
vfio/mlx5: Refactor PD usage
vfio/mlx5: Enforce a single SAVE command at a time
vfio: Extend the device migration protocol with PRE_COPY
...
Emulated VFIO devices are calling vfio_register_emulated_iommu_dev() and
consist of all the mdev drivers.
Like the physical drivers, support for iommufd is provided by the driver
supplying the correct standard ops. Provide ops from the core that
duplicate what vfio_register_emulated_iommu_dev() does.
Emulated drivers are where it is more likely to see variation in the
iommfd support ops. For instance IDXD will probably need to setup both a
iommfd_device context linked to a PASID and an iommufd_access context to
support all their mdev operations.
Link: https://lore.kernel.org/r/7-v4-42cd2eb0e3eb+335a-vfio_iommufd_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Lixiao Yang <lixiao.yang@intel.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Tested-by: Yu He <yu.he@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
There's already a device initialization callback that is used to
initialize the release completion workaround that was introduced
by commit ebb72b765f ("vfio/ccw: Use the new device life cycle
helpers").
Move the other elements of the vfio_ccw_private struct that
require distinct initialization over to that routine.
With that done, the vfio_ccw_alloc_private routine only does a
kzalloc, so fold it inline.
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20221104142007.1314999-4-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Move the stuff associated with the mdev parent (and thus the
subchannel struct) into its own struct, and leave the rest in
the existing private structure.
The subchannel will point to the parent, and the parent will point
to the private, for the areas where one or both are needed. Further
separation of these structs will follow.
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20221104142007.1314999-2-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Many of the mdev drivers use a simple counter for keeping track of the
available instances. Move this code to the core code and store the counter
in the mdev_parent. Implement it using correct locking, fixing mdpy.
Drivers just provide the value in the mdev_driver at registration time
and the core code takes care of maintaining it and exposing the value in
sysfs.
[hch: count instances per-parent instead of per-type, use an atomic_t
to avoid taking mdev_list_lock in the show method]
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/r/20220923092652.100656-15-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
ccw is the only exception which cannot use vfio_alloc_device() because
its private device structure is designed to serve both mdev and parent.
Life cycle of the parent is managed by css_driver so vfio_ccw_private
must be allocated/freed in css_driver probe/remove path instead of
conforming to vfio core life cycle for mdev.
Given that use a wait/completion scheme so the mdev remove path waits
after vfio_put_device() until receiving a completion notification from
@release. The completion indicates that all active references on
vfio_device have been released.
After that point although free of vfio_ccw_private is delayed to
css_driver it's at least guaranteed to have no parallel reference on
released vfio device part from other code paths.
memset() in @probe is removed. vfio_device is either already cleared
when probed for the first time or cleared in @release from last probe.
The right fix is to introduce separate structures for mdev and parent,
but this won't happen in short term per prior discussions.
Remove vfio_init/uninit_group_dev() as no user now.
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/r/20220921104401.38898-14-kevin.tian@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Part of the confusion that has existed is the FSM lifecycle of
subchannels between the common CSS driver and the vfio-ccw driver.
During configuration, the FSM state goes from NOT_OPER to STANDBY
to IDLE, but then back to NOT_OPER. For example:
vfio_ccw_sch_probe: VFIO_CCW_STATE_NOT_OPER
vfio_ccw_sch_probe: VFIO_CCW_STATE_STANDBY
vfio_ccw_mdev_probe: VFIO_CCW_STATE_IDLE
vfio_ccw_mdev_remove: VFIO_CCW_STATE_NOT_OPER
vfio_ccw_sch_remove: VFIO_CCW_STATE_NOT_OPER
vfio_ccw_sch_shutdown: VFIO_CCW_STATE_NOT_OPER
Rearrange the open/close events to align with the mdev open/close,
to better manage the memory and state of the devices as time
progresses. Specifically, make mdev_open() perform the FSM open,
and mdev_close() perform the FSM close instead of reset (which is
both close and open).
This makes the NOT_OPER state a dead-end path, indicating the
device is probably not recoverable without fully probing and
re-configuring the device.
This has the nice side-effect of removing a number of special-cases
where the FSM state is managed outside of the FSM itself (such as
the aforementioned mdev_close() routine).
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220707135737.720765-12-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Refactor the vfio_ccw_sch_quiesce() routine to extract the bit that
disables the subchannel and affects the FSM state. Use this to form
the basis of a CLOSE event that will mirror the OPEN event, and move
the subchannel back to NOT_OPER state.
A key difference with that mirroring is that while OPEN handles the
transition from NOT_OPER => STANDBY, the later probing of the mdev
handles the transition from STANDBY => IDLE. On the other hand,
the CLOSE event will move from one of the operating states {IDLE,
CP_PROCESSING, CP_PENDING} => NOT_OPER. That is, there is no stop
in a STANDBY state on the deconfigure path.
Add a call to cp_free() in this event, such that it is captured for
the various permutations of this event.
In the unlikely event that cio_disable_subchannel() returns -EBUSY,
the remaining logic of vfio_ccw_sch_quiesce() can still be used.
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220707135737.720765-10-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The FSM is in STANDBY state when arriving in vfio_ccw_mdev_probe(),
and this routine converts it to IDLE as part of its processing.
The error exit sets it to IDLE (again) but clears the private->mdev
pointer.
The FSM should of course be managing the state itself, but the
correct thing for vfio_ccw_mdev_probe() to do would be to put
the state back the way it found it.
The corresponding check of private->mdev in vfio_ccw_sch_io_todo()
can be removed, since the distinction is unnecessary at this point.
Fixes: 3bf1311f35 ("vfio/ccw: Convert to use vfio_register_emulated_iommu_dev()")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220707135737.720765-3-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
As vfio-ccw devices are created/destroyed, the uuid of the associated
mdevs that are recorded in $S390DBF/vfio_ccw_msg/sprintf get lost.
This is because a pointer to the UUID is stored instead of the UUID
itself, and that memory may have been repurposed if/when the logs are
examined. The result is usually garbage UUID data in the logs, though
there is an outside chance of an oops happening here.
Simply remove the UUID from the traces, as the subchannel number will
provide useful configuration information for problem determination,
and is stored directly into the log instead of a pointer.
As we were the only consumer of mdev_uuid(), remove that too.
Cc: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Michael Kawano <mkawano@linux.ibm.com>
Fixes: 60e05d1cf0 ("vfio-ccw: add some logging")
Fixes: b7701dfbf9 ("vfio-ccw: Register a chp_event callback for vfio-ccw")
[farman: reworded commit message, added Fixes: tags]
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Link: https://lore.kernel.org/r/20220707135737.720765-2-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This is a more complicated conversion because vfio_ccw is sharing the
vfio_device between both the mdev_device, its vfio_device and the
css_driver.
The mdev is a singleton, and the reason for this sharing is so the extra
css_driver function callbacks to be delivered to the vfio_device
implementation.
This keeps things as they are, with the css_driver allocating the
singleton, not the mdev_driver.
Embed the vfio_device in the vfio_ccw_private and instantiate it as a
vfio_device when the mdev probes. The drvdata of both the css_device and
the mdev_device point at the private, and container_of is used to get it
back from the vfio_device.
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v4-cea4f5bd2c00+b52-ccw_mdev_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The user can open multiple device FDs if it likes, however these open()
functions call vfio_register_notifier() on some device global
state. Calling vfio_register_notifier() twice in will trigger a WARN_ON
from notifier_chain_register() and the first close will wrongly delete the
notifier and more.
Since these really want the new open/close_device() semantics just change
the functions over.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/12-v4-9ea22c5e6afb+1adf-vfio_reflck_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
When an I/O request is made, the fsm_io_request() routine
moves the FSM state from IDLE to CP_PROCESSING, and then
fsm_io_helper() moves it to CP_PENDING if the START SUBCHANNEL
received a cc0. Yet, the error case to go from CP_PROCESSING
back to IDLE is done after the FSM call returns.
Let's move this up into the FSM proper, to provide some
better symmetry when unwinding in this case.
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Matthew Rosato <mjrosato@linux.ibm.com>
Message-Id: <20210511195631.3995081-3-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
The driver core standard is to pass in the properly typed object, the
properly typed attribute and the buffer data. It stems from the root
kobject method:
ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr,..)
Each subclass of kobject should provide their own function with the same
signature but more specific types, eg struct device uses:
ssize_t (*show)(struct device *dev, struct device_attribute *attr,..)
In this case the existing signature is:
ssize_t (*show)(struct kobject *kobj, struct device *dev,..)
Where kobj is a 'struct mdev_type *' and dev is 'mdev_type->parent->dev'.
Change the mdev_type related sysfs attribute functions to:
ssize_t (*show)(struct mdev_type *mtype, struct mdev_type_attribute *attr,..)
In order to restore type safety and match the driver core standard
There are no current users of 'attr', but if it is ever needed it would be
hard to add in retroactively, so do it now.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <18-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The kobj here is a type-erased version of mdev_type, which is already
stored in the struct mdev_device being passed in. It was only ever used to
compute the type_group_id, which is now extracted directly from the mdev.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <17-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The device is being unplugged, so pass the request to userspace to
ask for a graceful cleanup. This should free up the thread that
would otherwise loop waiting for the device to be fully released.
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This region provides a mechanism to pass a Channel Report Word
that affect vfio-ccw devices, and needs to be passed to the guest
for its awareness and/or processing.
The base driver (see crw_collect_info()) provides space for two
CRWs, as a subchannel event may have two CRWs chained together
(one for the ssid, one for the subchannel). As vfio-ccw will
deal with everything at the subchannel level, provide space
for a single CRW to be transferred in one shot.
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200505122745.53208-7-farman@linux.ibm.com>
[CH: added padding to ccw_crw_region]
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
The schib region can be used by userspace to get the subchannel-
information block (SCHIB) for the passthrough subchannel.
This can be useful to get information such as channel path
information via the SCHIB.PMCW fields.
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200505122745.53208-5-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This is mostly for the purposes of a later patch, since
we'll need to do the same thing later.
While we are at it, move the resulting function call to ahead
of the unregistering of the IOMMU notifier, so that it's done
in the reverse order of how it was created.
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200505122745.53208-4-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Usually, the common I/O layer logs various things into the s390
cio debug feature, which has been very helpful in the past when
looking at crash dumps. As vfio-ccw devices unbind from the
standard I/O subchannel driver, we lose some information there.
Let's introduce some vfio-ccw debug features and log some things
there. (Unfortunately we cannot reuse the cio debug feature from
a module.)
Message-Id: <20190816151505.9853-2-cohuck@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
When releasing the vfio-ccw mdev, we currently do not release
any existing channel program and its pinned pages. This can
lead to the following warning:
[1038876.561565] WARNING: CPU: 2 PID: 144727 at drivers/vfio/vfio_iommu_type1.c:1494 vfio_sanity_check_pfn_list+0x40/0x70 [vfio_iommu_type1]
....
1038876.561921] Call Trace:
[1038876.561935] ([<00000009897fb870>] 0x9897fb870)
[1038876.561949] [<000003ff8013bf62>] vfio_iommu_type1_detach_group+0xda/0x2f0 [vfio_iommu_type1]
[1038876.561965] [<000003ff8007b634>] __vfio_group_unset_container+0x64/0x190 [vfio]
[1038876.561978] [<000003ff8007b87e>] vfio_group_put_external_user+0x26/0x38 [vfio]
[1038876.562024] [<000003ff806fc608>] kvm_vfio_group_put_external_user+0x40/0x60 [kvm]
[1038876.562045] [<000003ff806fcb9e>] kvm_vfio_destroy+0x5e/0xd0 [kvm]
[1038876.562065] [<000003ff806f63fc>] kvm_put_kvm+0x2a4/0x3d0 [kvm]
[1038876.562083] [<000003ff806f655e>] kvm_vm_release+0x36/0x48 [kvm]
[1038876.562098] [<00000000003c2dc4>] __fput+0x144/0x228
[1038876.562113] [<000000000016ee82>] task_work_run+0x8a/0xd8
[1038876.562125] [<000000000014c7a8>] do_exit+0x5d8/0xd90
[1038876.562140] [<000000000014d084>] do_group_exit+0xc4/0xc8
[1038876.562155] [<000000000015c046>] get_signal+0x9ae/0xa68
[1038876.562169] [<0000000000108d66>] do_signal+0x66/0x768
[1038876.562185] [<0000000000b9e37e>] system_call+0x1ea/0x2d8
[1038876.562195] 2 locks held by qemu-system-s39/144727:
[1038876.562205] #0: 00000000537abaf9 (&container->group_lock){++++}, at: __vfio_group_unset_container+0x3c/0x190 [vfio]
[1038876.562230] #1: 00000000670008b5 (&iommu->lock){+.+.}, at: vfio_iommu_type1_detach_group+0x36/0x2f0 [vfio_iommu_type1]
[1038876.562250] Last Breaking-Event-Address:
[1038876.562262] [<000003ff8013aa24>] vfio_sanity_check_pfn_list+0x3c/0x70 [vfio_iommu_type1]
[1038876.562272] irq event stamp: 4236481
[1038876.562287] hardirqs last enabled at (4236489): [<00000000001cee7a>] console_unlock+0x6d2/0x740
[1038876.562299] hardirqs last disabled at (4236496): [<00000000001ce87e>] console_unlock+0xd6/0x740
[1038876.562311] softirqs last enabled at (4234162): [<0000000000b9fa1e>] __do_softirq+0x556/0x598
[1038876.562325] softirqs last disabled at (4234153): [<000000000014e4cc>] irq_exit+0xac/0x108
[1038876.562337] ---[ end trace 6c96d467b1c3ca06 ]---
Similarly we do not free the channel program when we are removing
the vfio-ccw device. Let's fix this by resetting the device and freeing
the channel program and pinned pages in the release path. For the remove
path we can just quiesce the device, since in the remove path the mediated
device is going away for good and so we don't need to do a full reset.
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Message-Id: <ae9f20dc8873f2027f7b3c5d2aaa0bdfe06850b8.1554756534.git.alifm@linux.ibm.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Add a region to the vfio-ccw device that can be used to submit
asynchronous I/O instructions. ssch continues to be handled by the
existing I/O region; the new region handles hsch and csch.
Interrupt status continues to be reported through the same channels
as for ssch.
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Allow to extend the regions used by vfio-ccw. The first user will be
handling of halt and clear subchannel.
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Introduce a mutex to disallow concurrent reads or writes to the
I/O region. This makes sure that the data the kernel or user
space see is always consistent.
The same mutex will be used to protect the async region as well.
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
The flow for processing ssch requests can be improved by splitting
the BUSY state:
- CP_PROCESSING: We reject any user space requests while we are in
the process of translating a channel program and submitting it to
the hardware. Use -EAGAIN to signal user space that it should
retry the request.
- CP_PENDING: We have successfully submitted a request with ssch and
are now expecting an interrupt. As we can't handle more than one
channel program being processed, reject any further requests with
-EBUSY. A final interrupt will move us out of this state.
By making this a separate state, we make it possible to issue a
halt or a clear while we're still waiting for the final interrupt
for the ssch (in a follow-on patch).
It also makes a lot of sense not to preemptively filter out writes to
the io_region if we're in an incorrect state: the state machine will
handle this correctly.
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
