Merge tag 's390-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 updates from Vasily Gorbik:

 - Improve stop_machine wait logic: replace cpu_relax_yield call in
   generic stop_machine function with a weak stop_machine_yield
   function. This is overridden on s390, which yields the current cpu to
   the neighbouring cpu after a couple of retries, instead of blindly
   giving up the cpu to the hipervisor. This significantly improves
   stop_machine performance on s390 in overcommitted scenarios.

   This includes common code changes which have been Acked by Peter
   Zijlstra and Thomas Gleixner.

 - Improve jump label transformation speed: transform jump labels
   without using stop_machine.

 - Refactoring of the vfio-ccw cp handling, simplifying the code and
   avoiding unneeded allocating/copying.

 - Various vfio-ccw fixes (ccw translation, state machine).

 - Add support for vfio-ap queue interrupt control in the guest. This
   includes s390 kvm changes which have been Acked by Christian
   Borntraeger.

 - Add protected virtualization support for virtio-ccw.

 - Enforce both CONFIG_SMP and CONFIG_HOTPLUG_CPU, which allows to
   remove some code which most likely isn't working at all, besides that
   s390 didn't even compile for !CONFIG_SMP.

 - Support for special flagged EP11 CPRBs for zcrypt.

 - Handle PCI devices with no support for new MIO instructions.

 - Avoid KASAN false positives in reworked stack unwinder.

 - Couple of fixes for the QDIO layer.

 - Convert s390 specific documentation to ReST format.

 - Let s390 crypto modules return -ENODEV instead of -EOPNOTSUPP if
   hardware is missing. This way our modules behave like most other
   modules and which is also what systemd's systemd-modules-load.service
   expects.

 - Replace defconfig with performance_defconfig, so there is one config
   file less to maintain.

 - Remove the SCLP call home device driver, which was never useful.

 - Cleanups all over the place.

* tag 's390-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (83 commits)
  docs: s390: s390dbf: typos and formatting, update crash command
  docs: s390: unify and update s390dbf kdocs at debug.c
  docs: s390: restore important non-kdoc parts of s390dbf.rst
  vfio-ccw: Fix the conversion of Format-0 CCWs to Format-1
  s390/pci: correctly handle MIO opt-out
  s390/pci: deal with devices that have no support for MIO instructions
  s390: ap: kvm: Enable PQAP/AQIC facility for the guest
  s390: ap: implement PAPQ AQIC interception in kernel
  vfio: ap: register IOMMU VFIO notifier
  s390: ap: kvm: add PQAP interception for AQIC
  s390/unwind: cleanup unused READ_ONCE_TASK_STACK
  s390/kasan: avoid false positives during stack unwind
  s390/qdio: don't touch the dsci in tiqdio_add_input_queues()
  s390/qdio: (re-)initialize tiqdio list entries
  s390/dasd: Fix a precision vs width bug in dasd_feature_list()
  s390/cio: introduce driver_override on the css bus
  vfio-ccw: make convert_ccw0_to_ccw1 static
  vfio-ccw: Remove copy_ccw_from_iova()
  vfio-ccw: Factor out the ccw0-to-ccw1 transition
  vfio-ccw: Copy CCW data outside length calculation
  ...

1 files changed, 23 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-css b/Documentation/ABI/testing/sysfs-bus-css
index 2979c40c10e9..966f8504bd7b 100644
--- a/Documentation/ABI/testing/sysfs-bus-css
+++ b/Documentation/ABI/testing/sysfs-bus-css
@@ -33,3 +33,26 @@ Description:	Contains the PIM/PAM/POM values, as reported by the
 		in sync with the values current in the channel subsystem).
 		Note: This is an I/O-subchannel specific attribute.
 Users:		s390-tools, HAL
+
+What:		/sys/bus/css/devices/.../driver_override
+Date:		June 2019
+Contact:	Cornelia Huck <cohuck@redhat.com>
+		linux-s390@vger.kernel.org
+Description:	This file allows the driver for a device to be specified. When
+		specified, only a driver with a name matching the value written
+		to driver_override will have an opportunity to bind to the
+		device. The override is specified by writing a string to the
+		driver_override file (echo vfio-ccw > driver_override) and
+		may be cleared with an empty string (echo > driver_override).
+		This returns the device to standard matching rules binding.
+		Writing to driver_override does not automatically unbind the
+		device from its current driver or make any attempt to
+		automatically load the specified driver.  If no driver with a
+		matching name is currently loaded in the kernel, the device
+		will not bind to any driver.  This also allows devices to
+		opt-out of driver binding using a driver_override name such as
+		"none".  Only a single driver may be specified in the override,
+		there is no support for parsing delimiters.
+		Note that unlike the mechanism of the same name for pci, this
+		file does not allow to override basic matching rules. I.e.,
+		the driver must still match the subchannel type of the device.