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, 14 insertions, 5 deletions

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 2b5a6754646f..b4f83f7bdf86 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -177,12 +177,18 @@ static void ack_state(struct multi_stop_data *msdata)
 		set_state(msdata, msdata->state + 1);
 }
 
+void __weak stop_machine_yield(const struct cpumask *cpumask)
+{
+	cpu_relax();
+}
+
 /* This is the cpu_stop function which stops the CPU. */
 static int multi_cpu_stop(void *data)
 {
 	struct multi_stop_data *msdata = data;
 	enum multi_stop_state curstate = MULTI_STOP_NONE;
 	int cpu = smp_processor_id(), err = 0;
+	const struct cpumask *cpumask;
 	unsigned long flags;
 	bool is_active;
 
@@ -192,15 +198,18 @@ static int multi_cpu_stop(void *data)
 	 */
 	local_save_flags(flags);
 
-	if (!msdata->active_cpus)
-		is_active = cpu == cpumask_first(cpu_online_mask);
-	else
-		is_active = cpumask_test_cpu(cpu, msdata->active_cpus);
+	if (!msdata->active_cpus) {
+		cpumask = cpu_online_mask;
+		is_active = cpu == cpumask_first(cpumask);
+	} else {
+		cpumask = msdata->active_cpus;
+		is_active = cpumask_test_cpu(cpu, cpumask);
+	}
 
 	/* Simple state machine */
 	do {
 		/* Chill out and ensure we re-read multi_stop_state. */
-		cpu_relax_yield();
+		stop_machine_yield(cpumask);
 		if (msdata->state != curstate) {
 			curstate = msdata->state;
 			switch (curstate) {