Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Ingo Molnar:
 "The changes in this cycle are:

   - RCU flavor consolidation cleanups and optmizations

   - Documentation updates

   - Miscellaneous fixes

   - SRCU updates

   - RCU-sync flavor consolidation

   - Torture-test updates

   - Linux-kernel memory-consistency-model updates, most notably the
     addition of plain C-language accesses"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (61 commits)
  tools/memory-model: Improve data-race detection
  tools/memory-model: Change definition of rcu-fence
  tools/memory-model: Expand definition of barrier
  tools/memory-model: Do not use "herd" to refer to "herd7"
  tools/memory-model: Fix comment in MP+poonceonces.litmus
  Documentation: atomic_t.txt: Explain ordering provided by smp_mb__{before,after}_atomic()
  rcu: Don't return a value from rcu_assign_pointer()
  rcu: Force inlining of rcu_read_lock()
  rcu: Fix irritating whitespace error in rcu_assign_pointer()
  rcu: Upgrade sync_exp_work_done() to smp_mb()
  rcutorture: Upper case solves the case of the vanishing NULL pointer
  torture: Suppress propagating trace_printk() warning
  rcutorture: Dump trace buffer for callback pipe drain failures
  torture: Add --trust-make to suppress "make clean"
  torture: Make --cpus override idleness calculations
  torture: Run kernel build in source directory
  torture: Add function graph-tracing cheat sheet
  torture: Capture qemu output
  rcutorture: Tweak kvm options
  rcutorture: Add trivial RCU implementation
  ...

29 files changed, 203 insertions, 89 deletions

diff --git a/tools/include/linux/rcu.h b/tools/include/linux/rcu.h
index 7d02527e5bce..9554d3fa54f3 100644
--- a/tools/include/linux/rcu.h
+++ b/tools/include/linux/rcu.h
@@ -19,7 +19,7 @@ static inline bool rcu_is_watching(void)
 	return false;
 }
 
-#define rcu_assign_pointer(p, v) ((p) = (v))
-#define RCU_INIT_POINTER(p, v) p=(v)
+#define rcu_assign_pointer(p, v)	do { (p) = (v); } while (0)
+#define RCU_INIT_POINTER(p, v)	do { (p) = (v); } while (0)
 
 #endif
diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell
index def9131d3d8e..5be86b1025e8 100644
--- a/tools/memory-model/linux-kernel.bell
+++ b/tools/memory-model/linux-kernel.bell
@@ -24,6 +24,7 @@ instructions RMW[{'once,'acquire,'release}]
 enum Barriers = 'wmb (*smp_wmb*) ||
 		'rmb (*smp_rmb*) ||
 		'mb (*smp_mb*) ||
+		'barrier (*barrier*) ||
 		'rcu-lock (*rcu_read_lock*)  ||
 		'rcu-unlock (*rcu_read_unlock*) ||
 		'sync-rcu (*synchronize_rcu*) ||
@@ -76,3 +77,8 @@ flag ~empty rcu-rscs & (po ; [Sync-srcu] ; po) as invalid-sleep
 
 (* Validate SRCU dynamic match *)
 flag ~empty different-values(srcu-rscs) as srcu-bad-nesting
+
+(* Compute marked and plain memory accesses *)
+let Marked = (~M) | IW | Once | Release | Acquire | domain(rmw) | range(rmw) |
+		LKR | LKW | UL | LF | RL | RU
+let Plain = M \ Marked
diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat
index 8dcb37835b61..ea2ff4b94074 100644
--- a/tools/memory-model/linux-kernel.cat
+++ b/tools/memory-model/linux-kernel.cat
@@ -24,8 +24,14 @@ include "lock.cat"
 (* Basic relations *)
 (*******************)
 
+(* Release Acquire *)
+let acq-po = [Acquire] ; po ; [M]
+let po-rel = [M] ; po ; [Release]
+let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po
+
 (* Fences *)
-let rmb = [R \ Noreturn] ; fencerel(Rmb) ; [R \ Noreturn]
+let R4rmb = R \ Noreturn	(* Reads for which rmb works *)
+let rmb = [R4rmb] ; fencerel(Rmb) ; [R4rmb]
 let wmb = [W] ; fencerel(Wmb) ; [W]
 let mb = ([M] ; fencerel(Mb) ; [M]) |
 	([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) |
@@ -34,13 +40,14 @@ let mb = ([M] ; fencerel(Mb) ; [M]) |
 	([M] ; po ; [UL] ; (co | po) ; [LKW] ;
 		fencerel(After-unlock-lock) ; [M])
 let gp = po ; [Sync-rcu | Sync-srcu] ; po?
-
 let strong-fence = mb | gp
 
-(* Release Acquire *)
-let acq-po = [Acquire] ; po ; [M]
-let po-rel = [M] ; po ; [Release]
-let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po
+let nonrw-fence = strong-fence | po-rel | acq-po
+let fence = nonrw-fence | wmb | rmb
+let barrier = fencerel(Barrier | Rmb | Wmb | Mb | Sync-rcu | Sync-srcu |
+		Before-atomic | After-atomic | Acquire | Release |
+		Rcu-lock | Rcu-unlock | Srcu-lock | Srcu-unlock) |
+	(po ; [Release]) | ([Acquire] ; po)
 
 (**********************************)
 (* Fundamental coherence ordering *)
@@ -61,21 +68,22 @@ empty rmw & (fre ; coe) as atomic
 let dep = addr | data
 let rwdep = (dep | ctrl) ; [W]
 let overwrite = co | fr
-let to-w = rwdep | (overwrite & int)
-let to-r = addr | (dep ; rfi)
-let fence = strong-fence | wmb | po-rel | rmb | acq-po
+let to-w = rwdep | (overwrite & int) | (addr ; [Plain] ; wmb)
+let to-r = addr | (dep ; [Marked] ; rfi)
 let ppo = to-r | to-w | fence | (po-unlock-rf-lock-po & int)
 
 (* Propagation: Ordering from release operations and strong fences. *)
-let A-cumul(r) = rfe? ; r
-let cumul-fence = A-cumul(strong-fence | po-rel) | wmb | po-unlock-rf-lock-po
-let prop = (overwrite & ext)? ; cumul-fence* ; rfe?
+let A-cumul(r) = (rfe ; [Marked])? ; r
+let cumul-fence = [Marked] ; (A-cumul(strong-fence | po-rel) | wmb |
+	po-unlock-rf-lock-po) ; [Marked]
+let prop = [Marked] ; (overwrite & ext)? ; cumul-fence* ;
+	[Marked] ; rfe? ; [Marked]
 
 (*
  * Happens Before: Ordering from the passage of time.
  * No fences needed here for prop because relation confined to one process.
  *)
-let hb = ppo | rfe | ((prop \ id) & int)
+let hb = [Marked] ; (ppo | rfe | ((prop \ id) & int)) ; [Marked]
 acyclic hb as happens-before
 
 (****************************************)
@@ -83,7 +91,7 @@ acyclic hb as happens-before
 (****************************************)
 
 (* Propagation: Each non-rf link needs a strong fence. *)
-let pb = prop ; strong-fence ; hb*
+let pb = prop ; strong-fence ; hb* ; [Marked]
 acyclic pb as propagation
 
 (*******)
@@ -114,24 +122,28 @@ let rcu-link = po? ; hb* ; pb* ; prop ; po
 
 (*
  * Any sequence containing at least as many grace periods as RCU read-side
- * critical sections (joined by rcu-link) acts as a generalized strong fence.
+ * critical sections (joined by rcu-link) induces order like a generalized
+ * inter-CPU strong fence.
  * Likewise for SRCU grace periods and read-side critical sections, provided
  * the synchronize_srcu() and srcu_read_[un]lock() calls refer to the same
  * struct srcu_struct location.
  *)
-let rec rcu-fence = rcu-gp | srcu-gp |
+let rec rcu-order = rcu-gp | srcu-gp |
 	(rcu-gp ; rcu-link ; rcu-rscsi) |
 	((srcu-gp ; rcu-link ; srcu-rscsi) & loc) |
 	(rcu-rscsi ; rcu-link ; rcu-gp) |
 	((srcu-rscsi ; rcu-link ; srcu-gp) & loc) |
-	(rcu-gp ; rcu-link ; rcu-fence ; rcu-link ; rcu-rscsi) |
-	((srcu-gp ; rcu-link ; rcu-fence ; rcu-link ; srcu-rscsi) & loc) |
-	(rcu-rscsi ; rcu-link ; rcu-fence ; rcu-link ; rcu-gp) |
-	((srcu-rscsi ; rcu-link ; rcu-fence ; rcu-link ; srcu-gp) & loc) |
-	(rcu-fence ; rcu-link ; rcu-fence)
+	(rcu-gp ; rcu-link ; rcu-order ; rcu-link ; rcu-rscsi) |
+	((srcu-gp ; rcu-link ; rcu-order ; rcu-link ; srcu-rscsi) & loc) |
+	(rcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; rcu-gp) |
+	((srcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; srcu-gp) & loc) |
+	(rcu-order ; rcu-link ; rcu-order)
+let rcu-fence = po ; rcu-order ; po?
+let fence = fence | rcu-fence
+let strong-fence = strong-fence | rcu-fence
 
 (* rb orders instructions just as pb does *)
-let rb = prop ; po ; rcu-fence ; po? ; hb* ; pb*
+let rb = prop ; rcu-fence ; hb* ; pb* ; [Marked]
 
 irreflexive rb as rcu
 
@@ -143,3 +155,49 @@ irreflexive rb as rcu
  * let xb = hb | pb | rb
  * acyclic xb as executes-before
  *)
+
+(*********************************)
+(* Plain accesses and data races *)
+(*********************************)
+
+(* Warn about plain writes and marked accesses in the same region *)
+let mixed-accesses = ([Plain & W] ; (po-loc \ barrier) ; [Marked]) |
+	([Marked] ; (po-loc \ barrier) ; [Plain & W])
+flag ~empty mixed-accesses as mixed-accesses
+
+(* Executes-before and visibility *)
+let xbstar = (hb | pb | rb)*
+let vis = cumul-fence* ; rfe? ; [Marked] ;
+	((strong-fence ; [Marked] ; xbstar) | (xbstar & int))
+
+(* Boundaries for lifetimes of plain accesses *)
+let w-pre-bounded = [Marked] ; (addr | fence)?
+let r-pre-bounded = [Marked] ; (addr | nonrw-fence |
+	([R4rmb] ; fencerel(Rmb) ; [~Noreturn]))?
+let w-post-bounded = fence? ; [Marked]
+let r-post-bounded = (nonrw-fence | ([~Noreturn] ; fencerel(Rmb) ; [R4rmb]))? ;
+	[Marked]
+
+(* Visibility and executes-before for plain accesses *)
+let ww-vis = fence | (strong-fence ; xbstar ; w-pre-bounded) |
+	(w-post-bounded ; vis ; w-pre-bounded)
+let wr-vis = fence | (strong-fence ; xbstar ; r-pre-bounded) |
+	(w-post-bounded ; vis ; r-pre-bounded)
+let rw-xbstar = fence | (r-post-bounded ; xbstar ; w-pre-bounded)
+
+(* Potential races *)
+let pre-race = ext & ((Plain * M) | ((M \ IW) * Plain))
+
+(* Coherence requirements for plain accesses *)
+let wr-incoh = pre-race & rf & rw-xbstar^-1
+let rw-incoh = pre-race & fr & wr-vis^-1
+let ww-incoh = pre-race & co & ww-vis^-1
+empty (wr-incoh | rw-incoh | ww-incoh) as plain-coherence
+
+(* Actual races *)
+let ww-nonrace = ww-vis & ((Marked * W) | rw-xbstar) & ((W * Marked) | wr-vis)
+let ww-race = (pre-race & co) \ ww-nonrace
+let wr-race = (pre-race & (co? ; rf)) \ wr-vis
+let rw-race = (pre-race & fr) \ rw-xbstar
+
+flag ~empty (ww-race | wr-race | rw-race) as data-race
diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def
index 551eeaa389d4..ef0f3c1850de 100644
--- a/tools/memory-model/linux-kernel.def
+++ b/tools/memory-model/linux-kernel.def
@@ -24,6 +24,7 @@ smp_mb__before_atomic() { __fence{before-atomic}; }
 smp_mb__after_atomic() { __fence{after-atomic}; }
 smp_mb__after_spinlock() { __fence{after-spinlock}; }
 smp_mb__after_unlock_lock() { __fence{after-unlock-lock}; }
+barrier() { __fence{barrier}; }
 
 // Exchange
 xchg(X,V)  __xchg{mb}(X,V)
diff --git a/tools/memory-model/litmus-tests/MP+poonceonces.litmus b/tools/memory-model/litmus-tests/MP+poonceonces.litmus
index b2b60b84fb9d..172f0145301c 100644
--- a/tools/memory-model/litmus-tests/MP+poonceonces.litmus
+++ b/tools/memory-model/litmus-tests/MP+poonceonces.litmus
@@ -1,7 +1,7 @@
 C MP+poonceonces
 
 (*
- * Result: Maybe
+ * Result: Sometimes
  *
  * Can the counter-intuitive message-passing outcome be prevented with
  * no ordering at all?
diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
index 5ee08f129094..681f9067fa9e 100644
--- a/tools/memory-model/litmus-tests/README
+++ b/tools/memory-model/litmus-tests/README
@@ -244,7 +244,7 @@ produce the name:
 Adding the ".litmus" suffix: SB+rfionceonce-poonceonces.litmus
 
 The descriptors that describe connections between consecutive accesses
-within the cycle through a given litmus test can be provided by the herd
+within the cycle through a given litmus test can be provided by the herd7
 tool (Rfi, Po, Fre, and so on) or by the linux-kernel.bell file (Once,
 Release, Acquire, and so on).
 
diff --git a/tools/memory-model/lock.cat b/tools/memory-model/lock.cat
index a059d1a6d8a2..6b52f365d73a 100644
--- a/tools/memory-model/lock.cat
+++ b/tools/memory-model/lock.cat
@@ -11,7 +11,7 @@
 include "cross.cat"
 
 (*
- * The lock-related events generated by herd are as follows:
+ * The lock-related events generated by herd7 are as follows:
  *
  * LKR		Lock-Read: the read part of a spin_lock() or successful
  *			spin_trylock() read-modify-write event pair
diff --git a/tools/memory-model/scripts/README b/tools/memory-model/scripts/README
index 29375a1fbbfa..095c7eb36f9f 100644
--- a/tools/memory-model/scripts/README
+++ b/tools/memory-model/scripts/README
@@ -22,7 +22,7 @@ checklitmushist.sh
 
 	Run all litmus tests having .litmus.out files from previous
 	initlitmushist.sh or newlitmushist.sh runs, comparing the
-	herd output to that of the original runs.
+	herd7 output to that of the original runs.
 
 checklitmus.sh
 
@@ -43,7 +43,7 @@ initlitmushist.sh
 
 judgelitmus.sh
 
-	Given a .litmus file and its .litmus.out herd output, check the
+	Given a .litmus file and its .litmus.out herd7 output, check the
 	.litmus.out file against the .litmus file's "Result:" comment to
 	judge whether the test ran correctly.  Not normally run manually,
 	provided instead for use by other scripts.
diff --git a/tools/memory-model/scripts/checkalllitmus.sh b/tools/memory-model/scripts/checkalllitmus.sh
index b35fcd61ecf6..3c0c7fbbd223 100755
--- a/tools/memory-model/scripts/checkalllitmus.sh
+++ b/tools/memory-model/scripts/checkalllitmus.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0+
 #
-# Run herd tests on all .litmus files in the litmus-tests directory
+# Run herd7 tests on all .litmus files in the litmus-tests directory
 # and check each file's result against a "Result:" comment within that
 # litmus test.  If the verification result does not match that specified
 # in the litmus test, this script prints an error message prefixed with
diff --git a/tools/memory-model/scripts/checklitmus.sh b/tools/memory-model/scripts/checklitmus.sh
index dd08801a30b0..11461ed40b5e 100755
--- a/tools/memory-model/scripts/checklitmus.sh
+++ b/tools/memory-model/scripts/checklitmus.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0+
 #
-# Run a herd test and invokes judgelitmus.sh to check the result against
+# Run a herd7 test and invokes judgelitmus.sh to check the result against
 # a "Result:" comment within the litmus test.  It also outputs verification
 # results to a file whose name is that of the specified litmus test, but
 # with ".out" appended.
diff --git a/tools/memory-model/scripts/parseargs.sh b/tools/memory-model/scripts/parseargs.sh
index 859e1d581e05..40f52080fdbd 100644
--- a/tools/memory-model/scripts/parseargs.sh
+++ b/tools/memory-model/scripts/parseargs.sh
@@ -91,7 +91,7 @@ do
 		shift
 		;;
 	--herdopts|--herdopt)
-		checkarg --destdir "(herd options)" "$#" "$2" '.*' '^--'
+		checkarg --destdir "(herd7 options)" "$#" "$2" '.*' '^--'
 		LKMM_HERD_OPTIONS="$2"
 		shift
 		;;
diff --git a/tools/memory-model/scripts/runlitmushist.sh b/tools/memory-model/scripts/runlitmushist.sh
index e507f5f933d5..6ed376f495bb 100644
--- a/tools/memory-model/scripts/runlitmushist.sh
+++ b/tools/memory-model/scripts/runlitmushist.sh
@@ -79,7 +79,7 @@ then
 	echo ' ---' Summary: 1>&2
 	grep '!!!' $T/*.sh.out 1>&2
 	nfail="`grep '!!!' $T/*.sh.out | wc -l`"
-	echo 'Number of failed herd runs (e.g., timeout): ' $nfail 1>&2
+	echo 'Number of failed herd7 runs (e.g., timeout): ' $nfail 1>&2
 	exit 1
 else
 	echo All runs completed successfully. 1>&2
diff --git a/tools/testing/radix-tree/linux/rcupdate.h b/tools/testing/radix-tree/linux/rcupdate.h
index fd280b070fdb..fed468fb0c78 100644
--- a/tools/testing/radix-tree/linux/rcupdate.h
+++ b/tools/testing/radix-tree/linux/rcupdate.h
@@ -7,6 +7,6 @@
 #define rcu_dereference_raw(p) rcu_dereference(p)
 #define rcu_dereference_protected(p, cond) rcu_dereference(p)
 #define rcu_dereference_check(p, cond) rcu_dereference(p)
-#define RCU_INIT_POINTER(p, v)	(p) = (v)
+#define RCU_INIT_POINTER(p, v)	do { (p) = (v); } while (0)
 
 #endif
diff --git a/tools/testing/selftests/rcutorture/Makefile b/tools/testing/selftests/rcutorture/Makefile
new file mode 100644
index 000000000000..5202dc666206
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0+
+all:
+	( cd ../../../..; tools/testing/selftests/rcutorture/bin/kvm.sh --duration 10 --configs TREE01 )
diff --git a/tools/testing/selftests/rcutorture/bin/configinit.sh b/tools/testing/selftests/rcutorture/bin/configinit.sh
index 40359486b3a8..93e80a42249a 100755
--- a/tools/testing/selftests/rcutorture/bin/configinit.sh
+++ b/tools/testing/selftests/rcutorture/bin/configinit.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0+
 #
-# Usage: configinit.sh config-spec-file build-output-dir results-dir
+# Usage: configinit.sh config-spec-file results-dir
 #
 # Create a .config file from the spec file.  Run from the kernel source tree.
 # Exits with 0 if all went well, with 1 if all went well but the config
@@ -11,10 +11,6 @@
 # desired settings, for example, "CONFIG_NO_HZ=y".  For best results,
 # this should be a full pathname.
 #
-# The second argument is a optional path to a build output directory,
-# for example, "O=/tmp/foo".  If this argument is omitted, the .config
-# file will be generated directly in the current directory.
-#
 # Copyright (C) IBM Corporation, 2013
 #
 # Authors: Paul E. McKenney <paulmck@linux.ibm.com>
@@ -26,34 +22,23 @@ mkdir $T
 # Capture config spec file.
 
 c=$1
-buildloc=$2
-resdir=$3
-builddir=
-if echo $buildloc | grep -q '^O='
-then
-	builddir=`echo $buildloc | sed -e 's/^O=//'`
-	if test ! -d $builddir
-	then
-		mkdir $builddir
-	fi
-else
-	echo Bad build directory: \"$buildloc\"
-	exit 2
-fi
+resdir=$2
 
 sed -e 's/^\(CONFIG[0-9A-Z_]*\)=.*$/grep -v "^# \1" |/' < $c > $T/u.sh
 sed -e 's/^\(CONFIG[0-9A-Z_]*=\).*$/grep -v \1 |/' < $c >> $T/u.sh
 grep '^grep' < $T/u.sh > $T/upd.sh
 echo "cat - $c" >> $T/upd.sh
-make mrproper
-make $buildloc distclean > $resdir/Make.distclean 2>&1
-make $buildloc $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1
-mv $builddir/.config $builddir/.config.sav
-sh $T/upd.sh < $builddir/.config.sav > $builddir/.config
-cp $builddir/.config $builddir/.config.new
-yes '' | make $buildloc oldconfig > $resdir/Make.oldconfig.out 2> $resdir/Make.oldconfig.err
+if test -z "$TORTURE_TRUST_MAKE"
+then
+	make clean > $resdir/Make.clean 2>&1
+fi
+make $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1
+mv .config .config.sav
+sh $T/upd.sh < .config.sav > .config
+cp .config .config.new
+yes '' | make oldconfig > $resdir/Make.oldconfig.out 2> $resdir/Make.oldconfig.err
 
 # verify new config matches specification.
-configcheck.sh $builddir/.config $c
+configcheck.sh .config $c
 
 exit 0
diff --git a/tools/testing/selftests/rcutorture/bin/cpus2use.sh b/tools/testing/selftests/rcutorture/bin/cpus2use.sh
index ff7102212703..4e9485590c10 100755
--- a/tools/testing/selftests/rcutorture/bin/cpus2use.sh
+++ b/tools/testing/selftests/rcutorture/bin/cpus2use.sh
@@ -9,6 +9,11 @@
 #
 # Authors: Paul E. McKenney <paulmck@linux.ibm.com>
 
+if test -n "$TORTURE_ALLOTED_CPUS"
+then
+	echo $TORTURE_ALLOTED_CPUS
+	exit 0
+fi
 ncpus=`grep '^processor' /proc/cpuinfo | wc -l`
 idlecpus=`mpstat | tail -1 | \
 	awk -v ncpus=$ncpus '{ print ncpus * ($7 + $NF) / 100 }'`
diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh
index 6bcb8b5b2ff2..c3a49fb4d6f6 100644
--- a/tools/testing/selftests/rcutorture/bin/functions.sh
+++ b/tools/testing/selftests/rcutorture/bin/functions.sh
@@ -172,7 +172,7 @@ identify_qemu_append () {
 	local console=ttyS0
 	case "$1" in
 	qemu-system-x86_64|qemu-system-i386)
-		echo noapic selinux=0 initcall_debug debug
+		echo selinux=0 initcall_debug debug
 		;;
 	qemu-system-aarch64)
 		console=ttyAMA0
@@ -191,8 +191,19 @@ identify_qemu_append () {
 # Output arguments for qemu arguments based on the TORTURE_QEMU_MAC
 # and TORTURE_QEMU_INTERACTIVE environment variables.
 identify_qemu_args () {
+	local KVM_CPU=""
+	case "$1" in
+	qemu-system-x86_64)
+		KVM_CPU=kvm64
+		;;
+	qemu-system-i386)
+		KVM_CPU=kvm32
+		;;
+	esac
 	case "$1" in
 	qemu-system-x86_64|qemu-system-i386)
+		echo -machine q35,accel=kvm
+		echo -cpu ${KVM_CPU}
 		;;
 	qemu-system-aarch64)
 		echo -machine virt,gic-version=host -cpu host
diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh b/tools/testing/selftests/rcutorture/bin/jitter.sh
index 435b60933985..dc49a3ba6111 100755
--- a/tools/testing/selftests/rcutorture/bin/jitter.sh
+++ b/tools/testing/selftests/rcutorture/bin/jitter.sh
@@ -34,10 +34,15 @@ do
 		exit 0;
 	fi
 
-	# Set affinity to randomly selected CPU
-	cpus=`ls /sys/devices/system/cpu/*/online |
-		sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//' |
-		grep -v '^0*$'`
+	# Set affinity to randomly selected online CPU
+	cpus=`grep 1 /sys/devices/system/cpu/*/online |
+		sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//'`
+
+	# Do not leave out poor old cpu0 which may not be hot-pluggable
+	if [ ! -f "/sys/devices/system/cpu/cpu0/online" ]; then
+		cpus="0 $cpus"
+	fi
+
 	cpumask=`awk -v cpus="$cpus" -v me=$me -v n=$n 'BEGIN {
 		srand(n + me + systime());
 		ncpus = split(cpus, ca);
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-build.sh b/tools/testing/selftests/rcutorture/bin/kvm-build.sh
index c27a0bbb9c02..18d6518504ee 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-build.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-build.sh
@@ -3,7 +3,7 @@
 #
 # Build a kvm-ready Linux kernel from the tree in the current directory.
 #
-# Usage: kvm-build.sh config-template build-dir resdir
+# Usage: kvm-build.sh config-template resdir
 #
 # Copyright (C) IBM Corporation, 2011
 #
@@ -15,8 +15,7 @@ then
 	echo "kvm-build.sh :$config_template: Not a readable file"
 	exit 1
 fi
-builddir=${2}
-resdir=${3}
+resdir=${2}
 
 T=${TMPDIR-/tmp}/test-linux.sh.$$
 trap 'rm -rf $T' 0
@@ -29,14 +28,14 @@ CONFIG_VIRTIO_PCI=y
 CONFIG_VIRTIO_CONSOLE=y
 ___EOF___
 
-configinit.sh $T/config O=$builddir $resdir
+configinit.sh $T/config $resdir
 retval=$?
 if test $retval -gt 1
 then
 	exit 2
 fi
 ncpus=`cpus2use.sh`
-make O=$builddir -j$ncpus $TORTURE_KMAKE_ARG > $resdir/Make.out 2>&1
+make -j$ncpus $TORTURE_KMAKE_ARG > $resdir/Make.out 2>&1
 retval=$?
 if test $retval -ne 0 || grep "rcu[^/]*": < $resdir/Make.out | egrep -q "Stop|Error|error:|warning:" || egrep -q "Stop|Error|error:" < $resdir/Make.out
 then
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh b/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh
index 8426fe1f15ee..1871d00bccd7 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh
@@ -11,6 +11,7 @@
 #
 # The "directory" above should end with the date/time directory, for example,
 # "tools/testing/selftests/rcutorture/res/2018.02.25-14:27:27".
+# Returns error status reflecting the success (or not) of the specified run.
 #
 # Copyright (C) IBM Corporation, 2018
 #
@@ -56,6 +57,8 @@ done
 if test -n "$files"
 then
 	$editor $files
+	exit 1
 else
 	echo No errors in console logs.
+	exit 0
 fi
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
index 2adde6aaafdb..e5edd5198725 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
@@ -7,6 +7,8 @@
 #
 # Usage: kvm-recheck.sh resdir ...
 #
+# Returns status reflecting the success or not of the last run specified.
+#
 # Copyright (C) IBM Corporation, 2011
 #
 # Authors: Paul E. McKenney <paulmck@linux.ibm.com>
@@ -28,8 +30,16 @@ do
 		TORTURE_SUITE="`cat $i/../TORTURE_SUITE`"
 		rm -f $i/console.log.*.diags
 		kvm-recheck-${TORTURE_SUITE}.sh $i
-		if test -f "$i/console.log"
+		if test -f "$i/qemu-retval" && test "`cat $i/qemu-retval`" -ne 0 && test "`cat $i/qemu-retval`" -ne 137
+		then
+			echo QEMU error, output:
+			cat $i/qemu-output
+		elif test -f "$i/console.log"
 		then
+			if test -f "$i/qemu-retval" && test "`cat $i/qemu-retval`" -eq 137
+			then
+				echo QEMU killed
+			fi
 			configcheck.sh $i/.config $i/ConfigFragment
 			if test -r $i/Make.oldconfig.err
 			then
@@ -58,3 +68,4 @@ do
 		fi
 	done
 done
+EDITOR=echo kvm-find-errors.sh "${@: -1}" > /dev/null 2>&1
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
index 0eb1ec16d78a..27b7b5693ede 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
@@ -36,11 +36,6 @@ config_template=${1}
 config_dir=`echo $config_template | sed -e 's,/[^/]*$,,'`
 title=`echo $config_template | sed -e 's/^.*\///'`
 builddir=${2}
-if test -z "$builddir" -o ! -d "$builddir" -o ! -w "$builddir"
-then
-	echo "kvm-test-1-run.sh :$builddir: Not a writable directory, cannot build into it"
-	exit 1
-fi
 resdir=${3}
 if test -z "$resdir" -o ! -d "$resdir" -o ! -w "$resdir"
 then
@@ -85,18 +80,18 @@ then
 	ln -s $base_resdir/.config $resdir  # for kvm-recheck.sh
 	# Arch-independent indicator
 	touch $resdir/builtkernel
-elif kvm-build.sh $T/Kc2 $builddir $resdir
+elif kvm-build.sh $T/Kc2 $resdir
 then
 	# Had to build a kernel for this test.
-	QEMU="`identify_qemu $builddir/vmlinux`"
+	QEMU="`identify_qemu vmlinux`"
 	BOOT_IMAGE="`identify_boot_image $QEMU`"
-	cp $builddir/vmlinux $resdir
-	cp $builddir/.config $resdir
-	cp $builddir/Module.symvers $resdir > /dev/null || :
-	cp $builddir/System.map $resdir > /dev/null || :
+	cp vmlinux $resdir
+	cp .config $resdir
+	cp Module.symvers $resdir > /dev/null || :
+	cp System.map $resdir > /dev/null || :
 	if test -n "$BOOT_IMAGE"
 	then
-		cp $builddir/$BOOT_IMAGE $resdir
+		cp $BOOT_IMAGE $resdir
 		KERNEL=$resdir/${BOOT_IMAGE##*/}
 		# Arch-independent indicator
 		touch $resdir/builtkernel
@@ -107,7 +102,7 @@ then
 	parse-build.sh $resdir/Make.out $title
 else
 	# Build failed.
-	cp $builddir/.config $resdir || :
+	cp .config $resdir || :
 	echo Build failed, not running KVM, see $resdir.
 	if test -f $builddir.wait
 	then
@@ -165,7 +160,7 @@ then
 fi
 echo "NOTE: $QEMU either did not run or was interactive" > $resdir/console.log
 echo $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append \"$qemu_append $boot_args\" > $resdir/qemu-cmd
-( $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append "$qemu_append $boot_args"& echo $! > $resdir/qemu_pid; wait `cat  $resdir/qemu_pid`; echo $? > $resdir/qemu-retval ) &
+( $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append "$qemu_append $boot_args" > $resdir/qemu-output 2>&1 & echo $! > $resdir/qemu_pid; wait `cat  $resdir/qemu_pid`; echo $? > $resdir/qemu-retval ) &
 commandcompleted=0
 sleep 10 # Give qemu's pid a chance to reach the file
 if test -s "$resdir/qemu_pid"
diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh
index 8f1e337b9b54..72518580df23 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm.sh
@@ -24,6 +24,7 @@ dur=$((30*60))
 dryrun=""
 KVM="`pwd`/tools/testing/selftests/rcutorture"; export KVM
 PATH=${KVM}/bin:$PATH; export PATH
+TORTURE_ALLOTED_CPUS=""
 TORTURE_DEFCONFIG=defconfig
 TORTURE_BOOT_IMAGE=""
 TORTURE_INITRD="$KVM/initrd"; export TORTURE_INITRD
@@ -32,6 +33,7 @@ TORTURE_KMAKE_ARG=""
 TORTURE_QEMU_MEM=512
 TORTURE_SHUTDOWN_GRACE=180
 TORTURE_SUITE=rcu
+TORTURE_TRUST_MAKE=""
 resdir=""
 configs=""
 cpus=0
@@ -62,6 +64,7 @@ usage () {
 	echo "       --qemu-cmd qemu-system-..."
 	echo "       --results absolute-pathname"
 	echo "       --torture rcu"
+	echo "       --trust-make"
 	exit 1
 }
 
@@ -89,6 +92,7 @@ do
 	--cpus)
 		checkarg --cpus "(number)" "$#" "$2" '^[0-9]*$' '^--'
 		cpus=$2
+		TORTURE_ALLOTED_CPUS="$2"
 		shift
 		;;
 	--datestamp)
@@ -173,6 +177,9 @@ do
 			jitter=0
 		fi
 		;;
+	--trust-make)
+		TORTURE_TRUST_MAKE="y"
+		;;
 	*)
 		echo Unknown argument $1
 		usage
@@ -285,6 +292,7 @@ cat << ___EOF___ > $T/script
 CONFIGFRAG="$CONFIGFRAG"; export CONFIGFRAG
 KVM="$KVM"; export KVM
 PATH="$PATH"; export PATH
+TORTURE_ALLOTED_CPUS="$TORTURE_ALLOTED_CPUS"; export TORTURE_ALLOTED_CPUS
 TORTURE_BOOT_IMAGE="$TORTURE_BOOT_IMAGE"; export TORTURE_BOOT_IMAGE
 TORTURE_BUILDONLY="$TORTURE_BUILDONLY"; export TORTURE_BUILDONLY
 TORTURE_DEFCONFIG="$TORTURE_DEFCONFIG"; export TORTURE_DEFCONFIG
@@ -297,6 +305,7 @@ TORTURE_QEMU_MAC="$TORTURE_QEMU_MAC"; export TORTURE_QEMU_MAC
 TORTURE_QEMU_MEM="$TORTURE_QEMU_MEM"; export TORTURE_QEMU_MEM
 TORTURE_SHUTDOWN_GRACE="$TORTURE_SHUTDOWN_GRACE"; export TORTURE_SHUTDOWN_GRACE
 TORTURE_SUITE="$TORTURE_SUITE"; export TORTURE_SUITE
+TORTURE_TRUST_MAKE="$TORTURE_TRUST_MAKE"; export TORTURE_TRUST_MAKE
 if ! test -e $resdir
 then
 	mkdir -p "$resdir" || :
@@ -342,7 +351,7 @@ function dump(first, pastlast, batchnum)
 	print "needqemurun="
 	jn=1
 	for (j = first; j < pastlast; j++) {
-		builddir=KVM "/b1"
+		builddir=KVM "/b" j - first + 1
 		cpusr[jn] = cpus[j];
 		if (cfrep[cf[j]] == "") {
 			cfr[jn] = cf[j];
@@ -358,7 +367,6 @@ function dump(first, pastlast, batchnum)
 		print "echo ", cfr[jn], cpusr[jn] ovf ": Starting build. `date` | tee -a " rd "log";
 		print "rm -f " builddir ".*";
 		print "touch " builddir ".wait";
-		print "mkdir " builddir " > /dev/null 2>&1 || :";
 		print "mkdir " rd cfr[jn] " || :";
 		print "kvm-test-1-run.sh " CONFIGDIR cf[j], builddir, rd cfr[jn], dur " \"" TORTURE_QEMU_ARG "\" \"" TORTURE_BOOTARGS "\" > " rd cfr[jn]  "/kvm-test-1-run.sh.out 2>&1 &"
 		print "echo ", cfr[jn], cpusr[jn] ovf ": Waiting for build to complete. `date` | tee -a " rd "log";
@@ -464,3 +472,5 @@ else
 fi
 
 # Tracing: trace_event=rcu:rcu_grace_period,rcu:rcu_future_grace_period,rcu:rcu_grace_period_init,rcu:rcu_nocb_wake,rcu:rcu_preempt_task,rcu:rcu_unlock_preempted_task,rcu:rcu_quiescent_state_report,rcu:rcu_fqs,rcu:rcu_callback,rcu:rcu_kfree_callback,rcu:rcu_batch_start,rcu:rcu_invoke_callback,rcu:rcu_invoke_kfree_callback,rcu:rcu_batch_end,rcu:rcu_torture_read,rcu:rcu_barrier
+# Function-graph tracing: ftrace=function_graph ftrace_graph_filter=sched_setaffinity,migration_cpu_stop
+# Also --kconfig "CONFIG_FUNCTION_TRACER=y CONFIG_FUNCTION_GRAPH_TRACER=y"
diff --git a/tools/testing/selftests/rcutorture/bin/parse-build.sh b/tools/testing/selftests/rcutorture/bin/parse-build.sh
index 0701b3bf6ade..09155c15ea65 100755
--- a/tools/testing/selftests/rcutorture/bin/parse-build.sh
+++ b/tools/testing/selftests/rcutorture/bin/parse-build.sh
@@ -21,7 +21,7 @@ mkdir $T
 
 . functions.sh
 
-if grep -q CC < $F
+if grep -q CC < $F || test -n "$TORTURE_TRUST_MAKE"
 then
 	:
 else
diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh
index 4508373a922f..4bf62d7b1cbc 100755
--- a/tools/testing/selftests/rcutorture/bin/parse-console.sh
+++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh
@@ -106,6 +106,7 @@ fi | tee -a $file.diags
 
 egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:|detected stalls on CPUs/tasks:|self-detected stall on CPU|Stall ended before state dump start|\?\?\? Writer stall state|rcu_.*kthread starved for' < $file |
 grep -v 'ODEBUG: ' |
+grep -v 'This means that this is a DEBUG kernel and it is' |
 grep -v 'Warning: unable to open an initial console' > $T.diags
 if test -s $T.diags
 then
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
index d2d2a86139db..e19a444a0684 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
+++ b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
@@ -1,2 +1,5 @@
 CONFIG_RCU_TORTURE_TEST=y
 CONFIG_PRINTK_TIME=y
+CONFIG_HYPERVISOR_GUEST=y
+CONFIG_PARAVIRT=y
+CONFIG_KVM_GUEST=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot b/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot
index ea47da95374b..d6da9a61d44a 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot
@@ -3,3 +3,4 @@ rcutree.gp_preinit_delay=3
 rcutree.gp_init_delay=3
 rcutree.gp_cleanup_delay=3
 rcu_nocbs=0
+rcutorture.fwd_progress=0
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL
new file mode 100644
index 000000000000..4d8eb5bfb6f6
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL
@@ -0,0 +1,14 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=8
+CONFIG_PREEMPT_NONE=y
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=n
+CONFIG_HZ_PERIODIC=n
+CONFIG_NO_HZ_IDLE=y
+CONFIG_NO_HZ_FULL=n
+CONFIG_HOTPLUG_CPU=n
+CONFIG_SUSPEND=n
+CONFIG_HIBERNATION=n
+CONFIG_DEBUG_LOCK_ALLOC=n
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_RCU_EXPERT=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot
new file mode 100644
index 000000000000..7017f5f5a55f
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot
@@ -0,0 +1,3 @@
+rcutorture.torture_type=trivial
+rcutorture.onoff_interval=0
+rcutorture.shuffle_interval=0