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, 193 insertions, 0 deletions

diff --git a/scripts/headerdep.pl b/scripts/headerdep.pl
new file mode 100755
index 000000000..ebfcbef43
--- /dev/null
+++ b/scripts/headerdep.pl
@@ -0,0 +1,193 @@
+#! /usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+#
+# Detect cycles in the header file dependency graph
+# Vegard Nossum <vegardno@ifi.uio.no>
+#
+
+use strict;
+use warnings;
+
+use Getopt::Long;
+
+my $opt_all;
+my @opt_include;
+my $opt_graph;
+
+&Getopt::Long::Configure(qw(bundling pass_through));
+&GetOptions(
+	help	=> \&help,
+	version	=> \&version,
+
+	all	=> \$opt_all,
+	"I=s"	=> \@opt_include,
+	graph	=> \$opt_graph,
+);
+
+push @opt_include, 'include';
+my %deps = ();
+my %linenos = ();
+
+my @headers = grep { strip($_) } @ARGV;
+
+parse_all(@headers);
+
+if($opt_graph) {
+	graph();
+} else {
+	detect_cycles(@headers);
+}
+
+
+sub help {
+	print "Usage: $0 [options] file...\n";
+	print "\n";
+	print "Options:\n";
+	print "  --all\n";
+	print "  --graph\n";
+	print "\n";
+	print "  -I includedir\n";
+	print "\n";
+	print "To make nice graphs, try:\n";
+	print "  $0 --graph include/linux/kernel.h | dot -Tpng -o graph.png\n";
+	exit;
+}
+
+sub version {
+	print "headerdep version 2\n";
+	exit;
+}
+
+# Get a file name that is relative to our include paths
+sub strip {
+	my $filename = shift;
+
+	for my $i (@opt_include) {
+		my $stripped = $filename;
+		$stripped =~ s/^$i\///;
+
+		return $stripped if $stripped ne $filename;
+	}
+
+	return $filename;
+}
+
+# Search for the file name in the list of include paths
+sub search {
+	my $filename = shift;
+	return $filename if -f $filename;
+
+	for my $i (@opt_include) {
+		my $path = "$i/$filename";
+		return $path if -f $path;
+	}
+	return;
+}
+
+sub parse_all {
+	# Parse all the headers.
+	my @queue = @_;
+	while(@queue) {
+		my $header = pop @queue;
+		next if exists $deps{$header};
+
+		$deps{$header} = [] unless exists $deps{$header};
+
+		my $path = search($header);
+		next unless $path;
+
+		open(my $file, '<', $path) or die($!);
+		chomp(my @lines = <$file>);
+		close($file);
+
+		for my $i (0 .. $#lines) {
+			my $line = $lines[$i];
+			if(my($dep) = ($line =~ m/^#\s*include\s*<(.*?)>/)) {
+				push @queue, $dep;
+				push @{$deps{$header}}, [$i + 1, $dep];
+			}
+		}
+	}
+}
+
+sub print_cycle {
+	# $cycle[n] includes $cycle[n + 1];
+	# $cycle[-1] will be the culprit
+	my $cycle = shift;
+
+	# Adjust the line numbers
+	for my $i (0 .. $#$cycle - 1) {
+		$cycle->[$i]->[0] = $cycle->[$i + 1]->[0];
+	}
+	$cycle->[-1]->[0] = 0;
+
+	my $first = shift @$cycle;
+	my $last = pop @$cycle;
+
+	my $msg = "In file included";
+	printf "%s from %s,\n", $msg, $last->[1] if defined $last;
+
+	for my $header (reverse @$cycle) {
+		printf "%s from %s:%d%s\n",
+			" " x length $msg,
+			$header->[1], $header->[0],
+			$header->[1] eq $last->[1] ? ' <-- here' : '';
+	}
+
+	printf "%s:%d: warning: recursive header inclusion\n",
+		$first->[1], $first->[0];
+}
+
+# Find and print the smallest cycle starting in the specified node.
+sub detect_cycles {
+	my @queue = map { [[0, $_]] } @_;
+	while(@queue) {
+		my $top = pop @queue;
+		my $name = $top->[-1]->[1];
+
+		for my $dep (@{$deps{$name}}) {
+			my $chain = [@$top, [$dep->[0], $dep->[1]]];
+
+			# If the dep already exists in the chain, we have a
+			# cycle...
+			if(grep { $_->[1] eq $dep->[1] } @$top) {
+				print_cycle($chain);
+				next if $opt_all;
+				return;
+			}
+
+			push @queue, $chain;
+		}
+	}
+}
+
+sub mangle {
+	$_ = shift;
+	s/\//__/g;
+	s/\./_/g;
+	s/-/_/g;
+	$_;
+}
+
+# Output dependency graph in GraphViz language.
+sub graph {
+	print "digraph {\n";
+
+	print "\t/* vertices */\n";
+	for my $header (keys %deps) {
+		printf "\t%s [label=\"%s\"];\n",
+			mangle($header), $header;
+	}
+
+	print "\n";
+
+	print "\t/* edges */\n";
+	for my $header (keys %deps) {
+		for my $dep (@{$deps{$header}}) {
+			printf "\t%s -> %s;\n",
+				mangle($header), mangle($dep->[1]);
+		}
+	}
+
+	print "}\n";
+}