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>

5 files changed, 555 insertions, 0 deletions

diff --git a/tools/testing/selftests/kselftest/ksft.py b/tools/testing/selftests/kselftest/ksft.py
new file mode 100644
index 000000000..0e030837f
--- /dev/null
+++ b/tools/testing/selftests/kselftest/ksft.py
@@ -0,0 +1,93 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2023 Collabora Ltd
+#
+# Kselftest helpers for outputting in KTAP format. Based on kselftest.h.
+#
+
+import sys
+
+ksft_cnt = {"pass": 0, "fail": 0, "skip": 0}
+ksft_num_tests = 0
+ksft_test_number = 1
+
+KSFT_PASS = 0
+KSFT_FAIL = 1
+KSFT_SKIP = 4
+
+
+def print_header():
+    print("TAP version 13")
+
+
+def set_plan(num_tests):
+    global ksft_num_tests
+    ksft_num_tests = num_tests
+    print("1..{}".format(num_tests))
+
+
+def print_cnts():
+    if ksft_cnt['skip'] > 0:
+        print(f"# {ksft_cnt['skip']} skipped test(s) detected. Consider enabling relevant config options to improve coverage.")
+
+    print(
+        f"# Totals: pass:{ksft_cnt['pass']} fail:{ksft_cnt['fail']} xfail:0 xpass:0 skip:{ksft_cnt['skip']} error:0"
+    )
+
+
+def print_msg(msg):
+    print(f"# {msg}")
+
+
+def _test_print(result, description, directive=None):
+    if directive:
+        directive_str = f"# {directive}"
+    else:
+        directive_str = ""
+
+    global ksft_test_number
+    print(f"{result} {ksft_test_number} {description} {directive_str}")
+    ksft_test_number += 1
+
+
+def test_result_pass(description):
+    _test_print("ok", description)
+    ksft_cnt["pass"] += 1
+
+
+def test_result_fail(description):
+    _test_print("not ok", description)
+    ksft_cnt["fail"] += 1
+
+
+def test_result_skip(description):
+    _test_print("ok", description, "SKIP")
+    ksft_cnt["skip"] += 1
+
+
+def test_result(condition, description=""):
+    if condition:
+        test_result_pass(description)
+    else:
+        test_result_fail(description)
+
+
+def finished():
+    if ksft_cnt["pass"] + ksft_cnt["skip"] == ksft_num_tests:
+        exit_code = KSFT_PASS
+    else:
+        exit_code = KSFT_FAIL
+
+    print_cnts()
+
+    sys.exit(exit_code)
+
+
+def exit_fail():
+    print_cnts()
+    sys.exit(KSFT_FAIL)
+
+
+def exit_pass():
+    print_cnts()
+    sys.exit(KSFT_PASS)
diff --git a/tools/testing/selftests/kselftest/ktap_helpers.sh b/tools/testing/selftests/kselftest/ktap_helpers.sh
new file mode 100644
index 000000000..32dbfe9da
--- /dev/null
+++ b/tools/testing/selftests/kselftest/ktap_helpers.sh
@@ -0,0 +1,126 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2023 Collabora Ltd
+#
+# Helpers for outputting in KTAP format
+#
+KTAP_TESTNO=1
+KTAP_CNT_PASS=0
+KTAP_CNT_FAIL=0
+KTAP_CNT_XFAIL=0
+KTAP_CNT_SKIP=0
+
+KSFT_PASS=0
+KSFT_FAIL=1
+KSFT_XFAIL=2
+KSFT_XPASS=3
+KSFT_SKIP=4
+
+KSFT_NUM_TESTS=0
+
+ktap_print_header() {
+	echo "TAP version 13"
+}
+
+ktap_print_msg()
+{
+	echo "#" $@
+}
+
+ktap_set_plan() {
+	KSFT_NUM_TESTS="$1"
+
+	echo "1..$KSFT_NUM_TESTS"
+}
+
+ktap_skip_all() {
+	echo -n "1..0 # SKIP "
+	echo $@
+}
+
+__ktap_test() {
+	result="$1"
+	description="$2"
+	directive="${3:-}" # optional
+
+	local directive_str=
+	[ ! -z "$directive" ] && directive_str="# $directive"
+
+	echo $result $KTAP_TESTNO $description $directive_str
+
+	KTAP_TESTNO=$((KTAP_TESTNO+1))
+}
+
+ktap_test_pass() {
+	description="$1"
+
+	result="ok"
+	__ktap_test "$result" "$description"
+
+	KTAP_CNT_PASS=$((KTAP_CNT_PASS+1))
+}
+
+ktap_test_skip() {
+	description="$1"
+
+	result="ok"
+	directive="SKIP"
+	__ktap_test "$result" "$description" "$directive"
+
+	KTAP_CNT_SKIP=$((KTAP_CNT_SKIP+1))
+}
+
+ktap_test_xfail() {
+	description="$1"
+
+	result="ok"
+	directive="XFAIL"
+	__ktap_test "$result" "$description" "$directive"
+
+	KTAP_CNT_XFAIL=$((KTAP_CNT_XFAIL+1))
+}
+
+ktap_test_fail() {
+	description="$1"
+
+	result="not ok"
+	__ktap_test "$result" "$description"
+
+	KTAP_CNT_FAIL=$((KTAP_CNT_FAIL+1))
+}
+
+ktap_test_result() {
+	description="$1"
+	shift
+
+	if $@; then
+		ktap_test_pass "$description"
+	else
+		ktap_test_fail "$description"
+	fi
+}
+
+ktap_exit_fail_msg() {
+	echo "Bail out! " $@
+	ktap_print_totals
+
+	exit "$KSFT_FAIL"
+}
+
+ktap_finished() {
+	ktap_print_totals
+
+	if [ $((KTAP_CNT_PASS + KTAP_CNT_SKIP + KTAP_CNT_XFAIL)) -eq "$KSFT_NUM_TESTS" ]; then
+		exit "$KSFT_PASS"
+	else
+		exit "$KSFT_FAIL"
+	fi
+}
+
+ktap_print_totals() {
+	if [ "$KTAP_CNT_SKIP" -gt 0 ]; then
+		echo "# $KTAP_CNT_SKIP skipped test(s) detected. " \
+			"Consider enabling relevant config options to improve coverage."
+	fi
+	echo "# Totals: pass:$KTAP_CNT_PASS fail:$KTAP_CNT_FAIL xfail:$KTAP_CNT_XFAIL xpass:0 skip:$KTAP_CNT_SKIP error:0"
+}
diff --git a/tools/testing/selftests/kselftest/module.sh b/tools/testing/selftests/kselftest/module.sh
new file mode 100755
index 000000000..51fb65159
--- /dev/null
+++ b/tools/testing/selftests/kselftest/module.sh
@@ -0,0 +1,84 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+
+#
+# Runs an individual test module.
+#
+# kselftest expects a separate executable for each test, this can be
+# created by adding a script like this:
+#
+#   #!/bin/sh
+#   SPDX-License-Identifier: GPL-2.0+
+#   $(dirname $0)/../kselftest/module.sh "description" module_name
+#
+# Example: tools/testing/selftests/lib/bitmap.sh
+
+desc=""				# Output prefix.
+module=""			# Filename (without the .ko).
+args=""				# modprobe arguments.
+
+modprobe="/sbin/modprobe"
+
+main() {
+    parse_args "$@"
+    assert_root
+    assert_have_module
+    run_module
+}
+
+parse_args() {
+    script=${0##*/}
+
+    if [ $# -lt 2 ]; then
+	echo "Usage: $script <description> <module_name> [FAIL]"
+	exit 1
+    fi
+
+    desc="$1"
+    shift || true
+    module="$1"
+    shift || true
+    args="$@"
+}
+
+assert_root() {
+    if [ ! -w /dev ]; then
+	skip "please run as root"
+    fi
+}
+
+assert_have_module() {
+    if ! $modprobe -q -n $module; then
+	skip "module $module is not found"
+    fi
+}
+
+run_module() {
+    if $modprobe -q $module $args; then
+	$modprobe -q -r $module
+	say "ok"
+    else
+	fail ""
+    fi
+}
+
+say() {
+    echo "$desc: $1"
+}
+
+
+fail() {
+    say "$1 [FAIL]" >&2
+    exit 1
+}
+
+skip() {
+    say "$1 [SKIP]" >&2
+    # Kselftest framework requirement - SKIP code is 4.
+    exit 4
+}
+
+#
+# Main script
+#
+main "$@"
diff --git a/tools/testing/selftests/kselftest/prefix.pl b/tools/testing/selftests/kselftest/prefix.pl
new file mode 100755
index 000000000..12a7f4ca2
--- /dev/null
+++ b/tools/testing/selftests/kselftest/prefix.pl
@@ -0,0 +1,24 @@
+#!/usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+# Prefix all lines with "# ", unbuffered. Command being piped in may need
+# to have unbuffering forced with "stdbuf -i0 -o0 -e0 $cmd".
+use strict;
+use IO::Handle;
+
+binmode STDIN;
+binmode STDOUT;
+
+STDOUT->autoflush(1);
+
+my $needed = 1;
+while (1) {
+	my $char;
+	my $bytes = sysread(STDIN, $char, 1);
+	exit 0 if ($bytes == 0);
+	if ($needed) {
+		print "# ";
+		$needed = 0;
+	}
+	print $char;
+	$needed = 1 if ($char eq "\n");
+}
diff --git a/tools/testing/selftests/kselftest/runner.sh b/tools/testing/selftests/kselftest/runner.sh
new file mode 100644
index 000000000..311811dc5
--- /dev/null
+++ b/tools/testing/selftests/kselftest/runner.sh
@@ -0,0 +1,228 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Runs a set of tests in a given subdirectory.
+
+# There isn't a shell-agnostic way to find the path of a sourced file,
+# so we must rely on BASE_DIR being set to find other tools.
+if [ -z "$BASE_DIR" ]; then
+	echo "Error: BASE_DIR must be set before sourcing." >&2
+	exit 1
+fi
+
+. ${BASE_DIR}/kselftest/ktap_helpers.sh
+
+export timeout_rc=124
+export logfile=/dev/stdout
+export per_test_logging=
+export per_test_log_dir=/tmp
+export RUN_IN_NETNS=
+
+# Defaults for "settings" file fields:
+# "timeout" how many seconds to let each test run before running
+# over our soft timeout limit.
+export kselftest_default_timeout=45
+
+TR_CMD=$(command -v tr)
+
+# If Perl is unavailable, we must fall back to line-at-a-time prefixing
+# with sed instead of unbuffered output.
+tap_prefix()
+{
+	if [ ! -x /usr/bin/perl ]; then
+		sed -e 's/^/# /'
+	else
+		"$BASE_DIR"/kselftest/prefix.pl
+	fi
+}
+
+tap_timeout()
+{
+	# Make sure tests will time out if utility is available.
+	if [ -x /usr/bin/timeout ] ; then
+		/usr/bin/timeout --foreground "$kselftest_timeout" \
+			/usr/bin/timeout "$kselftest_timeout" $1
+	else
+		$1
+	fi
+}
+
+run_one()
+{
+	DIR="$1"
+	TEST="$2"
+
+	BASENAME_TEST=$(basename $TEST)
+
+	# Reset any "settings"-file variables.
+	export kselftest_timeout="$kselftest_default_timeout"
+
+	# Safe default if tr not available
+	kselftest_cmd_args_ref="KSELFTEST_ARGS"
+
+	# Optional arguments for this command, possibly defined as an
+	# environment variable built using the test executable in all
+	# uppercase and sanitized substituting non acceptable shell
+	# variable name characters with "_" as in:
+	#
+	# 	KSELFTEST_<UPPERCASE_SANITIZED_TESTNAME>_ARGS="<options>"
+	#
+	# e.g.
+	#
+	# 	rtctest --> KSELFTEST_RTCTEST_ARGS="/dev/rtc1"
+	#
+	# 	cpu-on-off-test.sh --> KSELFTEST_CPU_ON_OFF_TEST_SH_ARGS="-a -p 10"
+	#
+	if [ -n "$TR_CMD" ]; then
+		BASENAME_SANITIZED=$(echo "$BASENAME_TEST" | \
+					$TR_CMD -d "[:blank:][:cntrl:]" | \
+					$TR_CMD -c "[:alnum:]_" "_" | \
+					$TR_CMD [:lower:] [:upper:])
+		kselftest_cmd_args_ref="KSELFTEST_${BASENAME_SANITIZED}_ARGS"
+	fi
+
+	# Load per-test-directory kselftest "settings" file.
+	settings="$BASE_DIR/$DIR/settings"
+	if [ -r "$settings" ] ; then
+		while read line ; do
+			# Skip comments.
+			if echo "$line" | grep -q '^#'; then
+				continue
+			fi
+			field=$(echo "$line" | cut -d= -f1)
+			value=$(echo "$line" | cut -d= -f2-)
+			eval "kselftest_$field"="$value"
+		done < "$settings"
+	fi
+
+	# Command line timeout overrides the settings file
+	if [ -n "$kselftest_override_timeout" ]; then
+		kselftest_timeout="$kselftest_override_timeout"
+		ktap_print_msg "overriding timeout to $kselftest_timeout" >> "$logfile"
+	else
+		ktap_print_msg "timeout set to $kselftest_timeout" >> "$logfile"
+	fi
+
+	TEST_HDR_MSG="selftests: $DIR: $BASENAME_TEST"
+	echo "# $TEST_HDR_MSG"
+	if [ ! -e "$TEST" ]; then
+		ktap_print_msg "Warning: file $TEST is missing!"
+		ktap_test_fail "$TEST_HDR_MSG"
+		rc=$KSFT_FAIL
+	else
+		if [ -x /usr/bin/stdbuf ]; then
+			stdbuf="/usr/bin/stdbuf --output=L "
+		fi
+		eval kselftest_cmd_args="\$${kselftest_cmd_args_ref:-}"
+		if [ -x "$TEST" ]; then
+			cmd="$stdbuf ./$BASENAME_TEST $kselftest_cmd_args"
+		elif [ -x "./ksft_runner.sh" ]; then
+			cmd="$stdbuf ./ksft_runner.sh ./$BASENAME_TEST"
+		else
+			ktap_print_msg "Warning: file $TEST is not executable"
+
+			if [ $(head -n 1 "$TEST" | cut -c -2) = "#!" ]
+			then
+				interpreter=$(head -n 1 "$TEST" | cut -c 3-)
+				cmd="$stdbuf $interpreter ./$BASENAME_TEST"
+			else
+				ktap_test_fail "$TEST_HDR_MSG"
+				return $KSFT_FAIL
+			fi
+		fi
+		cd `dirname $TEST` > /dev/null
+		(((( tap_timeout "$cmd" 2>&1; echo $? >&3) |
+			tap_prefix >&4) 3>&1) |
+			(read xs; exit $xs)) 4>>"$logfile"
+		rc=$?
+		case "$rc" in
+		"$KSFT_PASS")
+			ktap_test_pass "$TEST_HDR_MSG";;
+		"$KSFT_SKIP")
+			ktap_test_skip "$TEST_HDR_MSG";;
+		"$KSFT_XFAIL")
+			ktap_test_xfail "$TEST_HDR_MSG";;
+		"$timeout_rc")
+			ktap_test_fail "$TEST_HDR_MSG # TIMEOUT $kselftest_timeout seconds";;
+		*)
+			ktap_test_fail "$TEST_HDR_MSG # exit=$rc";;
+		esac
+		cd - >/dev/null
+	fi
+
+	return $rc
+}
+
+in_netns()
+{
+	local name=$1
+	ip netns exec $name bash <<-EOF
+		BASE_DIR=$BASE_DIR
+		source $BASE_DIR/kselftest/runner.sh
+		logfile=$logfile
+		run_one $DIR $TEST
+	EOF
+}
+
+run_in_netns()
+{
+	local tmplog="/tmp/$(mktemp -u ${BASENAME_TEST}-XXXXXX)"
+	local netns=$(mktemp -u ${BASENAME_TEST}-XXXXXX)
+	local rc
+
+	ip netns add $netns
+	if [ $? -ne 0 ]; then
+		ktap_print_msg "Warning: Create namespace failed for $BASENAME_TEST"
+		ktap_test_fail "selftests: $DIR: $BASENAME_TEST # Create NS failed"
+	fi
+	ip -n $netns link set lo up
+
+	in_netns $netns &> $tmplog
+	rc=$?
+
+	ip netns del $netns &> /dev/null
+	# Cat the log at once to avoid parallel netns logs.
+	cat $tmplog
+	rm -f $tmplog
+	return $rc
+}
+
+run_many()
+{
+	DIR="${PWD#${BASE_DIR}/}"
+	local rc
+	pids=
+
+	for TEST in "$@"; do
+		BASENAME_TEST=$(basename $TEST)
+		if [ -n "$per_test_logging" ]; then
+			logfile="$per_test_log_dir/$BASENAME_TEST"
+			cat /dev/null > "$logfile"
+		fi
+		if [ -n "$RUN_IN_NETNS" ]; then
+			run_in_netns &
+			pids="$pids $!"
+		else
+			run_one "$DIR" "$TEST"
+		fi
+	done
+
+	# These variables are outputs of ktap_helpers.sh but since we've
+	# run the test in a subprocess we need to update them manually
+	for pid in $pids; do
+		wait "$pid"
+		rc=$?
+		case "$rc" in
+		"$KSFT_PASS")
+			KTAP_CNT_PASS=$((KTAP_CNT_PASS + 1));;
+		"$KSFT_FAIL")
+			KTAP_CNT_FAIL=$((KTAP_CNT_FAIL + 1));;
+		"$KSFT_SKIP")
+			KTAP_CNT_SKIP=$((KTAP_CNT_SKIP + 1));;
+		"$KSFT_XFAIL")
+			KTAP_CNT_XFAIL=$((KTAP_CNT_XFAIL + 1));;
+		*)
+			KTAP_CNT_FAIL=$((KTAP_CNT_FAIL + 1));;
+		esac
+	done
+}