KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

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>

1 files changed, 98 insertions, 0 deletions

diff --git a/scripts/checkincludes.pl b/scripts/checkincludes.pl
new file mode 100755
index 000000000..b514a956d
--- /dev/null
+++ b/scripts/checkincludes.pl
@@ -0,0 +1,98 @@
+#!/usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+#
+# checkincludes: find/remove files included more than once
+#
+# Copyright abandoned, 2000, Niels Kristian Bech Jensen <nkbj@image.dk>.
+# Copyright 2009 Luis R. Rodriguez <mcgrof@gmail.com>
+#
+# This script checks for duplicate includes. It also has support
+# to remove them in place. Note that this will not take into
+# consideration macros so you should run this only if you know
+# you do have real dups and do not have them under #ifdef's. You
+# could also just review the results.
+
+use strict;
+
+sub usage {
+	print "Usage: checkincludes.pl [-r]\n";
+	print "By default we just warn of duplicates\n";
+	print "To remove duplicated includes in place use -r\n";
+	exit 1;
+}
+
+my $remove = 0;
+
+if ($#ARGV < 0) {
+	usage();
+}
+
+if ($#ARGV >= 1) {
+	if ($ARGV[0] =~ /^-/) {
+		if ($ARGV[0] eq "-r") {
+			$remove = 1;
+			shift;
+		} else {
+			usage();
+		}
+	}
+}
+
+my $dup_counter = 0;
+
+foreach my $file (@ARGV) {
+	open(my $f, '<', $file)
+	    or die "Cannot open $file: $!.\n";
+
+	my %includedfiles = ();
+	my @file_lines = ();
+
+	while (<$f>) {
+		if (m/^\s*#\s*include\s*[<"](\S*)[>"]/o) {
+			++$includedfiles{$1};
+		}
+		push(@file_lines, $_);
+	}
+
+	close($f);
+
+	if (!$remove) {
+		foreach my $filename (keys %includedfiles) {
+			if ($includedfiles{$filename} > 1) {
+				print "$file: $filename is included more than once.\n";
+				++$dup_counter;
+			}
+		}
+		next;
+	}
+
+	open($f, '>', $file)
+	    or die("Cannot write to $file: $!");
+
+	my $dups = 0;
+	foreach (@file_lines) {
+		if (m/^\s*#\s*include\s*[<"](\S*)[>"]/o) {
+			foreach my $filename (keys %includedfiles) {
+				if ($1 eq $filename) {
+					if ($includedfiles{$filename} > 1) {
+						$includedfiles{$filename}--;
+						$dups++;
+						++$dup_counter;
+					} else {
+						print {$f} $_;
+					}
+				}
+			}
+		} else {
+			print {$f} $_;
+		}
+	}
+	if ($dups > 0) {
+		print "$file: removed $dups duplicate includes\n";
+	}
+	close($f);
+}
+
+if ($dup_counter == 0) {
+	print "No duplicate includes found.\n";
+}