KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 301 insertions, 0 deletions

diff --git a/tools/bootconfig/scripts/bconf2ftrace.sh b/tools/bootconfig/scripts/bconf2ftrace.sh
new file mode 100755
index 000000000..850c20734
--- /dev/null
+++ b/tools/bootconfig/scripts/bconf2ftrace.sh
@@ -0,0 +1,301 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+
+usage() {
+	echo "Ftrace boottime trace test tool"
+	echo "Usage: $0 [--apply|--init] [--debug] BOOTCONFIG-FILE"
+	echo "    --apply: Test actual apply to tracefs (need sudo)"
+	echo "    --init:  Initialize ftrace before applying (imply --apply)"
+	exit 1
+}
+
+[ $# -eq 0 ] && usage
+
+BCONF=
+DEBUG=
+APPLY=
+INIT=
+while [ x"$1" != x ]; do
+	case "$1" in
+	"--debug")
+		DEBUG=$1;;
+	"--apply")
+		APPLY=$1;;
+	"--init")
+		APPLY=$1
+		INIT=$1;;
+	*)
+		[ ! -f $1 ] && usage
+		BCONF=$1;;
+	esac
+	shift 1
+done
+
+if [ x"$APPLY" != x ]; then
+	if [ `id -u` -ne 0 ]; then
+		echo "This must be run by root user. Try sudo." 1>&2
+		exec sudo $0 $DEBUG $APPLY $BCONF
+	fi
+fi
+
+run_cmd() { # command
+	echo "$*"
+	if [ x"$APPLY" != x ]; then # apply command
+		eval $*
+	fi
+}
+
+if [ x"$DEBUG" != x ]; then
+	set -x
+fi
+
+TRACEFS=`grep -m 1 -w tracefs /proc/mounts | cut -f 2 -d " "`
+if [ -z "$TRACEFS" ]; then
+	if ! grep -wq debugfs /proc/mounts; then
+		echo "Error: No tracefs/debugfs was mounted." 1>&2
+		exit 1
+	fi
+	TRACEFS=`grep -m 1 -w debugfs /proc/mounts | cut -f 2 -d " "`/tracing
+	if [ ! -d $TRACEFS ]; then
+		echo "Error: ftrace is not enabled on this kernel." 1>&2
+		exit 1
+	fi
+fi
+
+if [ x"$INIT" != x ]; then
+	. `dirname $0`/ftrace.sh
+	(cd $TRACEFS; initialize_ftrace)
+fi
+
+. `dirname $0`/xbc.sh
+
+######## main #########
+set -e
+
+xbc_init $BCONF
+
+set_value_of() { # key file
+	if xbc_has_key $1; then
+		val=`xbc_get_val $1 1`
+		run_cmd "echo '$val' >> $2"
+	fi
+}
+
+set_array_of() { # key file
+	if xbc_has_key $1; then
+		xbc_get_val $1 | while read line; do
+			run_cmd "echo '$line' >> $2"
+		done
+	fi
+}
+
+compose_synth() { # event_name branch
+	echo -n "$1 "
+	xbc_get_val $2 | while read field; do echo -n "$field; "; done
+}
+
+print_hist_array() { # prefix key
+	__sep="="
+	if xbc_has_key ${1}.${2}; then
+		echo -n ":$2"
+		xbc_get_val ${1}.${2} | while read field; do
+			echo -n "$__sep$field"; __sep=","
+		done
+	fi
+}
+
+print_hist_action_array() { # prefix key
+	__sep="("
+	echo -n ".$2"
+	xbc_get_val ${1}.${2} | while read field; do
+		echo -n "$__sep$field"; __sep=","
+	done
+	echo -n ")"
+}
+
+print_hist_one_action() { # prefix handler param
+	echo -n ":${2}("`xbc_get_val ${1}.${3}`")"
+	if xbc_has_key "${1}.trace"; then
+		print_hist_action_array ${1} "trace"
+	elif xbc_has_key "${1}.save"; then
+		print_hist_action_array ${1} "save"
+	elif xbc_has_key "${1}.snapshot"; then
+		echo -n ".snapshot()"
+	fi
+}
+
+print_hist_actions() { # prefix handler param
+	for __hdr in `xbc_subkeys ${1}.${2} 1 ".[0-9]"`; do
+		print_hist_one_action ${1}.${2}.$__hdr ${2} ${3}
+	done
+	if xbc_has_key ${1}.${2}.${3} ; then
+		print_hist_one_action ${1}.${2} ${2} ${3}
+	fi
+}
+
+print_hist_var() { # prefix varname
+	echo -n ":${2}="`xbc_get_val ${1}.var.${2} | tr -d [:space:]`
+}
+
+print_one_histogram() { # prefix
+	echo -n "hist"
+	print_hist_array $1 "keys"
+	print_hist_array $1 "values"
+	print_hist_array $1 "sort"
+	if xbc_has_key "${1}.size"; then
+		echo -n ":size="`xbc_get_val ${1}.size`
+	fi
+	if xbc_has_key "${1}.name"; then
+		echo -n ":name="`xbc_get_val ${1}.name`
+	fi
+	for __var in `xbc_subkeys "${1}.var" 1`; do
+		print_hist_var ${1} ${__var}
+	done
+	if xbc_has_key "${1}.pause"; then
+		echo -n ":pause"
+	elif xbc_has_key "${1}.continue"; then
+		echo -n ":continue"
+	elif xbc_has_key "${1}.clear"; then
+		echo -n ":clear"
+	fi
+	print_hist_actions ${1} "onmax" "var"
+	print_hist_actions ${1} "onchange" "var"
+	print_hist_actions ${1} "onmatch" "event"
+
+	if xbc_has_key "${1}.filter"; then
+		echo -n " if "`xbc_get_val ${1}.filter`
+	fi
+}
+
+setup_one_histogram() { # prefix trigger-file
+	run_cmd "echo '`print_one_histogram ${1}`' >> ${2}"
+}
+
+setup_histograms() { # prefix trigger-file
+	for __hist in `xbc_subkeys ${1} 1 ".[0-9]"`; do
+		setup_one_histogram ${1}.$__hist ${2}
+	done
+	if xbc_has_key ${1}.keys; then
+		setup_one_histogram ${1} ${2}
+	fi
+}
+
+setup_event() { # prefix group event [instance]
+	branch=$1.$2.$3
+	if [ "$4" ]; then
+		eventdir="$TRACEFS/instances/$4/events/$2/$3"
+	else
+		eventdir="$TRACEFS/events/$2/$3"
+	fi
+	# group enable
+	if [ "$3" = "enable" ]; then
+		run_cmd "echo 1 > ${eventdir}"
+		return
+	fi
+
+	case $2 in
+	kprobes)
+		xbc_get_val ${branch}.probes | while read line; do
+			run_cmd "echo 'p:kprobes/$3 $line' >> $TRACEFS/kprobe_events"
+		done
+		;;
+	synthetic)
+		run_cmd "echo '`compose_synth $3 ${branch}.fields`' >> $TRACEFS/synthetic_events"
+		;;
+	esac
+
+	set_value_of ${branch}.filter ${eventdir}/filter
+	set_array_of ${branch}.actions ${eventdir}/trigger
+
+	setup_histograms ${branch}.hist ${eventdir}/trigger
+
+	if xbc_has_key ${branch}.enable; then
+		run_cmd "echo 1 > ${eventdir}/enable"
+	fi
+}
+
+setup_events() { # prefix("ftrace" or "ftrace.instance.INSTANCE") [instance]
+	prefix="${1}.event"
+	if xbc_has_branch ${1}.event; then
+		for grpev in `xbc_subkeys ${1}.event 2`; do
+			setup_event $prefix ${grpev%.*} ${grpev#*.} $2
+		done
+	fi
+	if xbc_has_branch ${1}.event.enable; then
+		if [ "$2" ]; then
+			run_cmd "echo 1 > $TRACEFS/instances/$2/events/enable"
+		else
+			run_cmd "echo 1 > $TRACEFS/events/enable"
+		fi
+	fi
+}
+
+size2kb() { # size[KB|MB]
+	case $1 in
+	*KB)
+		echo ${1%KB};;
+	*MB)
+		expr ${1%MB} \* 1024;;
+	*)
+		expr $1 / 1024 ;;
+	esac
+}
+
+setup_instance() { # [instance]
+	if [ "$1" ]; then
+		instance="ftrace.instance.${1}"
+		instancedir=$TRACEFS/instances/$1
+	else
+		instance="ftrace"
+		instancedir=$TRACEFS
+	fi
+
+	set_array_of ${instance}.options ${instancedir}/trace_options
+	set_value_of ${instance}.trace_clock ${instancedir}/trace_clock
+	set_value_of ${instance}.cpumask ${instancedir}/tracing_cpumask
+	set_value_of ${instance}.tracing_on ${instancedir}/tracing_on
+	set_value_of ${instance}.tracer ${instancedir}/current_tracer
+	set_array_of ${instance}.ftrace.filters \
+		${instancedir}/set_ftrace_filter
+	set_array_of ${instance}.ftrace.notrace \
+		${instancedir}/set_ftrace_notrace
+
+	if xbc_has_key ${instance}.alloc_snapshot; then
+		run_cmd "echo 1 > ${instancedir}/snapshot"
+	fi
+
+	if xbc_has_key ${instance}.buffer_size; then
+		size=`xbc_get_val ${instance}.buffer_size 1`
+		size=`eval size2kb $size`
+		run_cmd "echo $size >> ${instancedir}/buffer_size_kb"
+	fi
+
+	setup_events ${instance} $1
+	set_array_of ${instance}.events ${instancedir}/set_event
+}
+
+# ftrace global configs (kernel.*)
+if xbc_has_key "kernel.dump_on_oops"; then
+	dump_mode=`xbc_get_val "kernel.dump_on_oops" 1`
+	[ "$dump_mode" ] && dump_mode=`eval echo $dump_mode` || dump_mode=1
+	run_cmd "echo \"$dump_mode\" > /proc/sys/kernel/ftrace_dump_on_oops"
+fi
+
+set_value_of kernel.fgraph_max_depth $TRACEFS/max_graph_depth
+set_array_of kernel.fgraph_filters $TRACEFS/set_graph_function
+set_array_of kernel.fgraph_notraces $TRACEFS/set_graph_notrace
+
+# Per-instance/per-event configs
+if ! xbc_has_branch "ftrace" ; then
+	exit 0
+fi
+
+setup_instance # root instance
+
+if xbc_has_branch "ftrace.instance"; then
+	for i in `xbc_subkeys "ftrace.instance" 1`; do
+		run_cmd "mkdir -p $TRACEFS/instances/$i"
+		setup_instance $i
+	done
+fi
+