From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Wed, 23 Sep 2026 09:37:21 -0700
Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host
 migration

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 tools/docs/documentation-file-ref-check | 245 ++++++++++++++++++++++++++++++++
 1 file changed, 245 insertions(+)
 create mode 100755 tools/docs/documentation-file-ref-check

(limited to 'tools/docs/documentation-file-ref-check')

diff --git a/tools/docs/documentation-file-ref-check b/tools/docs/documentation-file-ref-check
new file mode 100755
index 000000000..93b53f3a5
--- /dev/null
+++ b/tools/docs/documentation-file-ref-check
@@ -0,0 +1,245 @@
+#!/usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+#
+# Treewide grep for references to files under Documentation, and report
+# non-existing files in stderr.
+
+use warnings;
+use strict;
+use Getopt::Long qw(:config no_auto_abbrev);
+
+# NOTE: only add things here when the file was gone, but the text wants
+# to mention a past documentation file, for example, to give credits for
+# the original work.
+my %false_positives = (
+	"Documentation/scsi/scsi_mid_low_api.rst" => "Documentation/Configure.help",
+	"drivers/vhost/vhost.c" => "Documentation/virtual/lguest/lguest.c",
+);
+
+my $scriptname = $0;
+$scriptname =~ s,tools/docs/([^/]+/),$1,;
+
+# Parse arguments
+my $help = 0;
+my $fix = 0;
+my $warn = 0;
+
+if (! -e ".git") {
+	printf "Warning: can't check if file exists, as this is not a git tree\n";
+	exit 0;
+}
+
+GetOptions(
+	'fix' => \$fix,
+	'warn' => \$warn,
+	'h|help|usage' => \$help,
+);
+
+if ($help != 0) {
+    print "$scriptname [--help] [--fix]\n";
+    exit -1;
+}
+
+# Step 1: find broken references
+print "Finding broken references. This may take a while...  " if ($fix);
+
+my %broken_ref;
+
+my $doc_fix = 0;
+
+open IN, "git grep ':doc:\`' Documentation/|"
+     or die "Failed to run git grep";
+while (<IN>) {
+	next if (!m,^([^:]+):.*\:doc\:\`([^\`]+)\`,);
+	next if (m,sphinx/,);
+
+	my $file = $1;
+	my $d = $1;
+	my $doc_ref = $2;
+
+	my $f = $doc_ref;
+
+	$d =~ s,(.*/).*,$1,;
+	$f =~ s,.*\<([^\>]+)\>,$1,;
+
+	if ($f =~ m,^/,) {
+		$f = "$f.rst";
+		$f =~ s,^/,Documentation/,;
+	} else {
+		$f = "$d$f.rst";
+	}
+
+	next if (grep -e, glob("$f"));
+
+	if ($fix && !$doc_fix) {
+		print STDERR "\nWARNING: Currently, can't fix broken :doc:`` fields\n";
+	}
+	$doc_fix++;
+
+	print STDERR "$file: :doc:`$doc_ref`\n";
+}
+close IN;
+
+open IN, "git grep 'Documentation/'|"
+     or die "Failed to run git grep";
+while (<IN>) {
+	next if (!m/^([^:]+):(.*)/);
+
+	my $f = $1;
+	my $ln = $2;
+
+	# On linux-next, discard the Next/ directory
+	next if ($f =~ m,^Next/,);
+
+	# Makefiles and scripts contain nasty expressions to parse docs
+	next if ($f =~ m/Makefile/ || $f =~ m/\.(sh|py|pl|~|rej|org|orig)$/);
+
+	# It doesn't make sense to parse hidden files
+	next if ($f =~ m#/\.#);
+
+	# Skip this script
+	next if ($f eq $scriptname);
+
+	# Ignore the dir where documentation will be built
+	next if ($ln =~ m,\b(\S*)Documentation/output,);
+
+	if ($ln =~ m,\b(\S*)(Documentation/[A-Za-z0-9\_\.\,\~/\*\[\]\?+-]*)(.*),) {
+		my $prefix = $1;
+		my $ref = $2;
+		my $base = $2;
+		my $extra = $3;
+
+		# some file references are like:
+		# /usr/src/linux/Documentation/DMA-{API,mapping}.txt
+		# For now, ignore them
+		next if ($extra =~ m/^{/);
+
+		# Remove footnotes at the end like:
+		# Documentation/devicetree/dt-object-internal.txt[1]
+		$ref =~ s/(txt|rst)\[\d+]$/$1/;
+
+		# Remove ending ']' without any '['
+		$ref =~ s/\].*// if (!($ref =~ m/\[/));
+
+		# Remove puntuation marks at the end
+		$ref =~ s/[\,\.]+$//;
+
+		my $fulref = "$prefix$ref";
+
+		$fulref =~ s/^(\<file|ref)://;
+		$fulref =~ s/^[\'\`]+//;
+		$fulref =~ s,^\$\(.*\)/,,;
+		$base =~ s,.*/,,;
+
+		# Remove URL false-positives
+		next if ($fulref =~ m/^http/);
+
+		# Remove sched-pelt false-positive
+		next if ($fulref =~ m,^Documentation/scheduler/sched-pelt$,);
+
+		# Discard some build examples from Documentation/target/tcm_mod_builder.rst
+		next if ($fulref =~ m,mnt/sdb/lio-core-2.6.git/Documentation/target,);
+
+		# Check if exists, evaluating wildcards
+		next if (grep -e, glob("$ref $fulref"));
+
+		# Accept relative Documentation paths for tools/
+		if ($f =~ m/tools/) {
+			my $path = $f;
+			$path =~ s,(.*)/.*,$1,;
+			$path =~ s,testing/selftests/bpf,bpf/bpftool,;
+			next if (grep -e, glob("$path/$ref $path/../$ref $path/$fulref"));
+		}
+
+		# Discard known false-positives
+		if (defined($false_positives{$f})) {
+			next if ($false_positives{$f} eq $fulref);
+		}
+
+		if ($fix) {
+			if (!($ref =~ m/(scripts|Kconfig|Kbuild)/)) {
+				$broken_ref{$ref}++;
+			}
+		} elsif ($warn) {
+			print STDERR "Warning: $f references a file that doesn't exist: $fulref\n";
+		} else {
+			print STDERR "$f: $fulref\n";
+		}
+	}
+}
+close IN;
+
+exit 0 if (!$fix);
+
+# Step 2: Seek for file name alternatives
+print "Auto-fixing broken references. Please double-check the results\n";
+
+foreach my $ref (keys %broken_ref) {
+	my $new =$ref;
+
+	my $basedir = ".";
+	# On translations, only seek inside the translations directory
+	$basedir  = $1 if ($ref =~ m,(Documentation/translations/[^/]+),);
+
+	# get just the basename
+	$new =~ s,.*/,,;
+
+	my $f="";
+
+	# usual reason for breakage: DT file moved around
+	if ($ref =~ /devicetree/) {
+		# usual reason for breakage: DT file renamed to .yaml
+		if (!$f) {
+			my $new_ref = $ref;
+			$new_ref =~ s/\.txt$/.yaml/;
+			$f=$new_ref if (-f $new_ref);
+		}
+
+		if (!$f) {
+			my $search = $new;
+			$search =~ s,^.*/,,;
+			$f = qx(find Documentation/devicetree/ -iname "*$search*") if ($search);
+			if (!$f) {
+				# Manufacturer name may have changed
+				$search =~ s/^.*,//;
+				$f = qx(find Documentation/devicetree/ -iname "*$search*") if ($search);
+			}
+		}
+	}
+
+	# usual reason for breakage: file renamed to .rst
+	if (!$f) {
+		$new =~ s/\.txt$/.rst/;
+		$f=qx(find $basedir -iname $new) if ($new);
+	}
+
+	# usual reason for breakage: use dash or underline
+	if (!$f) {
+		$new =~ s/[-_]/[-_]/g;
+		$f=qx(find $basedir -iname $new) if ($new);
+	}
+
+	# Wild guess: seek for the same name on another place
+	if (!$f) {
+		$f = qx(find $basedir -iname $new) if ($new);
+	}
+
+	my @find = split /\s+/, $f;
+
+	if (!$f) {
+		print STDERR "ERROR: Didn't find a replacement for $ref\n";
+	} elsif (scalar(@find) > 1) {
+		print STDERR "WARNING: Won't auto-replace, as found multiple files close to $ref:\n";
+		foreach my $j (@find) {
+			$j =~ s,^./,,;
+			print STDERR "    $j\n";
+		}
+	} else {
+		$f = $find[0];
+		$f =~ s,^./,,;
+		print "INFO: Replacing $ref to $f\n";
+		foreach my $j (qx(git grep -l $ref)) {
+			qx(sed "s\@$ref\@$f\@g" -i $j);
+		}
+	}
+}
-- 
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