linux-stable.git/drivers/s390, branch linux-5.14.y

s390/cio: make ccw_device_dma_* more robust

2021-11-17T10:04:48+00:00

commit ad9a14517263a16af040598c7920c09ca9670a31 upstream.

Since commit 48720ba56891 ("virtio/s390: use DMA memory for ccw I/O and
classic notifiers") we were supposed to make sure that
virtio_ccw_release_dev() completes before the ccw device and the
attached dma pool are torn down, but unfortunately we did not.  Before
that commit it used to be OK to delay cleaning up the memory allocated
by virtio-ccw indefinitely (which isn't really intuitive for guys used
to destruction happens in reverse construction order), but now we
trigger a BUG_ON if the genpool is destroyed before all memory allocated
from it is deallocated. Which brings down the guest. We can observe this
problem, when unregister_virtio_device() does not give up the last
reference to the virtio_device (e.g. because a virtio-scsi attached scsi
disk got removed without previously unmounting its previously mounted
partition).

To make sure that the genpool is only destroyed after all the necessary
freeing is done let us take a reference on the ccw device on each
ccw_device_dma_zalloc() and give it up on each ccw_device_dma_free().

Actually there are multiple approaches to fixing the problem at hand
that can work. The upside of this one is that it is the safest one while
remaining simple. We don't crash the guest even if the driver does not
pair allocations and frees. The downside is the reference counting
overhead, that the reference counting for ccw devices becomes more
complex, in a sense that we need to pair the calls to the aforementioned
functions for it to be correct, and that if we happen to leak, we leak
more than necessary (the whole ccw device instead of just the genpool).

Some alternatives to this approach are taking a reference in
virtio_ccw_online() and giving it up in virtio_ccw_release_dev() or
making sure virtio_ccw_release_dev() completes its work before
virtio_ccw_remove() returns. The downside of these approaches is that
these are less safe against programming errors.

Cc:  # v5.3
Signed-off-by: Halil Pasic 
Fixes: 48720ba56891 ("virtio/s390: use DMA memory for ccw I/O and classic notifiers")
Reported-by: bfu@redhat.com
Reviewed-by: Vineeth Vijayan 
Acked-by: Cornelia Huck 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

s390/ap: Fix hanging ioctl caused by orphaned replies

2021-11-17T10:04:48+00:00

commit 3826350e6dd435e244eb6e47abad5a47c169ebc2 upstream.

When a queue is switched to soft offline during heavy load and later
switched to soft online again and now used, it may be that the caller
is blocked forever in the ioctl call.

The failure occurs because there is a pending reply after the queue(s)
have been switched to offline. This orphaned reply is received when
the queue is switched to online and is accidentally counted for the
outstanding replies. So when there was a valid outstanding reply and
this orphaned reply is received it counts as the outstanding one thus
dropping the outstanding counter to 0. Voila, with this counter the
receive function is not called any more and the real outstanding reply
is never received (until another request comes in...) and the ioctl
blocks.

The fix is simple. However, instead of readjusting the counter when an
orphaned reply is detected, I check the queue status for not empty and
compare this to the outstanding counter. So if the queue is not empty
then the counter must not drop to 0 but at least have a value of 1.

Signed-off-by: Harald Freudenberger 
Cc: stable@vger.kernel.org
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

s390/tape: fix timer initialization in tape_std_assign()

2021-11-17T10:04:48+00:00

commit 213fca9e23b59581c573d558aa477556f00b8198 upstream.

commit 9c6c273aa424 ("timer: Remove init_timer_on_stack() in favor
of timer_setup_on_stack()") changed the timer setup from
init_timer_on_stack(() to timer_setup(), but missed to change the
mod_timer() call. And while at it, use msecs_to_jiffies() instead
of the open coded timeout calculation.

Cc: stable@vger.kernel.org
Fixes: 9c6c273aa424 ("timer: Remove init_timer_on_stack() in favor of timer_setup_on_stack()")
Signed-off-by: Sven Schnelle 
Reviewed-by: Vasily Gorbik 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

s390/cio: check the subchannel validity for dev_busid

2021-11-17T10:04:48+00:00

commit a4751f157c194431fae9e9c493f456df8272b871 upstream.

Check the validity of subchanel before reading other fields in
the schib.

Fixes: d3683c055212 ("s390/cio: add dev_busid sysfs entry for each subchannel")
CC: 
Reported-by: Cornelia Huck 
Signed-off-by: Vineeth Vijayan 
Reviewed-by: Cornelia Huck 
Link: https://lore.kernel.org/r/20211105154451.847288-1-vneethv@linux.ibm.com
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

s390/qeth: fix deadlock during failing recovery

2021-10-07T05:53:03+00:00

[ Upstream commit d2b59bd4b06d84a4eadb520b0f71c62fe8ec0a62 ]

Commit 0b9902c1fcc5 ("s390/qeth: fix deadlock during recovery") removed
taking discipline_mutex inside qeth_do_reset(), fixing potential
deadlocks. An error path was missed though, that still takes
discipline_mutex and thus has the original deadlock potential.

Intermittent deadlocks were seen when a qeth channel path is configured
offline, causing a race between qeth_do_reset and ccwgroup_remove.
Call qeth_set_offline() directly in the qeth_do_reset() error case and
then a new variant of ccwgroup_set_offline(), without taking
discipline_mutex.

Fixes: b41b554c1ee7 ("s390/qeth: fix locking for discipline setup / removal")
Signed-off-by: Alexandra Winter 
Reviewed-by: Julian Wiedmann 
Signed-off-by: Julian Wiedmann 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

s390/qeth: Fix deadlock in remove_discipline

2021-10-07T05:53:03+00:00

[ Upstream commit ee909d0b1dac8632eeb78cbf17661d6c7674bbd0 ]

Problem: qeth_close_dev_handler is a worker that tries to acquire
card->discipline_mutex via drv->set_offline() in ccwgroup_set_offline().
Since commit b41b554c1ee7
("s390/qeth: fix locking for discipline setup / removal")
qeth_remove_discipline() is called under card->discipline_mutex and
cancels the work and waits for it to finish.

STOPLAN reception with reason code IPA_RC_VEPA_TO_VEB_TRANSITION is the
only situation that schedules close_dev_work. In that situation scheduling
qeth recovery will also result in an offline interface, when resetting the
isolation mode fails, if the external switch is still set to VEB.
And since commit 0b9902c1fcc5 ("s390/qeth: fix deadlock during recovery")
qeth recovery does not aquire card->discipline_mutex anymore.

So we accept the longer pathlength of qeth_schedule_recovery in this
error situation and re-use the existing function.

As a side-benefit this changes the hwtrap to behave like during recovery
instead of like during a user-triggered set_offline.

Fixes: b41b554c1ee7 ("s390/qeth: fix locking for discipline setup / removal")
Signed-off-by: Alexandra Winter 
Acked-by: Julian Wiedmann 
Signed-off-by: Julian Wiedmann 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

s390/qeth: fix NULL deref in qeth_clear_working_pool_list()

2021-09-30T08:13:00+00:00

[ Upstream commit 248f064af222a1f97ee02c84a98013dfbccad386 ]

When qeth_set_online() calls qeth_clear_working_pool_list() to roll
back after an error exit from qeth_hardsetup_card(), we are at risk of
accessing card->qdio.in_q before it was allocated by
qeth_alloc_qdio_queues() via qeth_mpc_initialize().

qeth_clear_working_pool_list() then dereferences NULL, and by writing to
queue->bufs[i].pool_entry scribbles all over the CPU's lowcore.
Resulting in a crash when those lowcore areas are used next (eg. on
the next machine-check interrupt).

Such a scenario would typically happen when the device is first set
online and its queues aren't allocated yet. An early IO error or certain
misconfigs (eg. mismatched transport mode, bad portno) then cause us to
error out from qeth_hardsetup_card() with card->qdio.in_q still being
NULL.

Fix it by checking the pointer for NULL before accessing it.

Note that we also have (rare) paths inside qeth_mpc_initialize() where
a configuration change can cause us to free the existing queues,
expecting that subsequent code will allocate them again. If we then
error out before that re-allocation happens, the same bug occurs.

Fixes: eff73e16ee11 ("s390/qeth: tolerate pre-filled RX buffer")
Reported-by: Stefan Raspl 
Root-caused-by: Heiko Carstens 
Signed-off-by: Julian Wiedmann 
Reviewed-by: Alexandra Winter 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

s390/sclp: fix Secure-IPL facility detection

2021-09-22T10:39:18+00:00

commit d76b14f3971a0638b6cd0da289f8b48acee287d0 upstream.

Prevent out-of-range access if the returned SCLP SCCB response is smaller
in size than the address of the Secure-IPL flag.

Fixes: c9896acc7851 ("s390/ipl: Provide has_secure sysfs attribute")
Cc: stable@vger.kernel.org # 5.2+
Signed-off-by: Alexander Egorenkov 
Reviewed-by: Christian Borntraeger 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

s390/qdio: cancel the ESTABLISH ccw after timeout

2021-09-18T11:43:23+00:00

commit 1c1dc8bda3a05c60877a6649775894db5343bdea upstream.

When the ESTABLISH ccw does not complete within the specified timeout,
try our best to cancel the ccw program that is still active on the
device. Otherwise the IO subsystem might be accessing it even after
the driver eg. called qdio_free().

Fixes: 779e6e1c724d ("[S390] qdio: new qdio driver.")
Signed-off-by: Julian Wiedmann 
Reviewed-by: Benjamin Block 
Cc:  # 2.6.27
Signed-off-by: Heiko Carstens 
Signed-off-by: Greg Kroah-Hartman

s390/qdio: fix roll-back after timeout on ESTABLISH ccw

2021-09-18T11:43:23+00:00

commit 2c197870e4701610ec3b1143808d4e31152caf30 upstream.

When qdio_establish() times out while waiting for the ESTABLISH ccw to
complete, it calls qdio_shutdown() to roll back all of its previous
actions. But at this point the qdio_irq's state is still
QDIO_IRQ_STATE_INACTIVE, so qdio_shutdown() will exit immediately
without doing any actual work.

Which means that eg. the qdio_irq's thinint-indicator stays registered,
and cdev->handler isn't restored to its old value. And since
commit 954d6235be41 ("s390/qdio: make thinint registration symmetric")
the qdio_irq also stays on the tiq_list, so on the next qdio_establish()
we might get a helpful BUG from the list-debugging code:

...
[ 4633.512591] list_add double add: new=00000000005a4110, prev=00000001b357db78, next=00000000005a4110.
[ 4633.512621] ------------[ cut here ]------------
[ 4633.512623] kernel BUG at lib/list_debug.c:29!
...
[ 4633.512796]  [<00000001b2c6ee9a>] __list_add_valid+0x82/0xa0
[ 4633.512798] ([<00000001b2c6ee96>] __list_add_valid+0x7e/0xa0)
[ 4633.512800]  [<00000001b2fcecce>] qdio_establish_thinint+0x116/0x190
[ 4633.512805]  [<00000001b2fcbe58>] qdio_establish+0x128/0x498
...

Fix this by extracting a goto-chain from the existing error exits in
qdio_establish(), and check the return value of the wait_event_...()
to detect the timeout condition.

Fixes: 779e6e1c724d ("[S390] qdio: new qdio driver.")
Root-caused-by: Benjamin Block 
Signed-off-by: Julian Wiedmann 
Reviewed-by: Benjamin Block 
Cc:  # 2.6.27
Signed-off-by: Heiko Carstens 
Signed-off-by: Greg Kroah-Hartman