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, 275 insertions, 0 deletions

diff --git a/lib/tests/cmdline_kunit.c b/lib/tests/cmdline_kunit.c
new file mode 100644
index 000000000..3f61ff8d3
--- /dev/null
+++ b/lib/tests/cmdline_kunit.c
@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Test cases for API provided by cmdline.c
+ */
+
+#include <kunit/test.h>
+#include <linux/kernel.h>
+#include <linux/random.h>
+#include <linux/sizes.h>
+#include <linux/string.h>
+
+static const char *cmdline_test_strings[] = {
+	"\"\"", ""  , "=" , "\"-", ","    , "-,"   , ",-"   , "-" ,
+	"+,"  , "--", ",,", "''" , "\"\",", "\",\"", "-\"\"", "\"",
+};
+
+static const int cmdline_test_values[] = {
+	1, 1, 1, 1, 2, 3, 2, 3,
+	1, 3, 2, 1, 1, 1, 3, 1,
+};
+
+static_assert(ARRAY_SIZE(cmdline_test_strings) == ARRAY_SIZE(cmdline_test_values));
+
+static const char *cmdline_test_range_strings[] = {
+	"-7" , "--7"  , "-1-2"    , "7--9",
+	"7-" , "-7--9", "7-9,"    , "9-7" ,
+	"5-a", "a-5"  , "5-8"     , ",8-5",
+	"+,1", "-,4"  , "-3,0-1,6", "4,-" ,
+	" +2", " -9"  , "0-1,-3,6", "- 9" ,
+};
+
+static const int cmdline_test_range_values[][16] = {
+	{ 1, -7, }, { 0, -0, }, { 4, -1, 0, +1, 2, }, { 0, 7, },
+	{ 0, +7, }, { 0, -7, }, { 3, +7, 8, +9, 0, }, { 0, 9, },
+	{ 0, +5, }, { 0, -0, }, { 4, +5, 6, +7, 8, }, { 0, 0, },
+	{ 0, +0, }, { 0, -0, }, { 4, -3, 0, +1, 6, }, { 1, 4, },
+	{ 0, +0, }, { 0, -0, }, { 4, +0, 1, -3, 6, }, { 0, 0, },
+};
+
+static_assert(ARRAY_SIZE(cmdline_test_range_strings) == ARRAY_SIZE(cmdline_test_range_values));
+
+static void cmdline_do_one_test(struct kunit *test, const char *in, int rc, int offset)
+{
+	const char *fmt = "Pattern: %s";
+	const char *out = in;
+	int dummy;
+	int ret;
+
+	ret = get_option((char **)&out, &dummy);
+
+	KUNIT_EXPECT_EQ_MSG(test, ret, rc, fmt, in);
+	KUNIT_EXPECT_PTR_EQ_MSG(test, out, in + offset, fmt, in);
+}
+
+static void cmdline_test_noint(struct kunit *test)
+{
+	unsigned int i = 0;
+
+	do {
+		const char *str = cmdline_test_strings[i];
+		int rc = 0;
+		int offset;
+
+		/* Only first and leading '-' will advance the pointer */
+		offset = !!(*str == '-');
+		cmdline_do_one_test(test, str, rc, offset);
+	} while (++i < ARRAY_SIZE(cmdline_test_strings));
+}
+
+static void cmdline_test_lead_int(struct kunit *test)
+{
+	unsigned int i = 0;
+	char in[32];
+
+	do {
+		const char *str = cmdline_test_strings[i];
+		int rc = cmdline_test_values[i];
+		int offset;
+
+		sprintf(in, "%u%s", get_random_u8(), str);
+		/* Only first '-' after the number will advance the pointer */
+		offset = strlen(in) - strlen(str) + !!(rc == 2);
+		cmdline_do_one_test(test, in, rc, offset);
+	} while (++i < ARRAY_SIZE(cmdline_test_strings));
+}
+
+static void cmdline_test_tail_int(struct kunit *test)
+{
+	unsigned int i = 0;
+	char in[32];
+
+	do {
+		const char *str = cmdline_test_strings[i];
+		/* When "" or "-" the result will be valid integer */
+		int rc = strcmp(str, "") ? (strcmp(str, "-") ? 0 : 1) : 1;
+		int offset;
+
+		sprintf(in, "%s%u", str, get_random_u8());
+		/*
+		 * Only first and leading '-' not followed by integer
+		 * will advance the pointer.
+		 */
+		offset = rc ? strlen(in) : !!(*str == '-');
+		cmdline_do_one_test(test, in, rc, offset);
+	} while (++i < ARRAY_SIZE(cmdline_test_strings));
+}
+
+static void cmdline_do_one_range_test(struct kunit *test, const char *in,
+				      unsigned int n, const int *e)
+{
+	unsigned int i;
+	int r[16];
+	int *p;
+
+	memset(r, 0, sizeof(r));
+	get_options(in, ARRAY_SIZE(r), r);
+	KUNIT_EXPECT_EQ_MSG(test, r[0], e[0], "in test %u (parsed) expected %d numbers, got %d",
+			    n, e[0], r[0]);
+	for (i = 1; i < ARRAY_SIZE(r); i++)
+		KUNIT_EXPECT_EQ_MSG(test, r[i], e[i], "in test %u at %u", n, i);
+
+	memset(r, 0, sizeof(r));
+	get_options(in, 0, r);
+	KUNIT_EXPECT_EQ_MSG(test, r[0], e[0], "in test %u (validated) expected %d numbers, got %d",
+			    n, e[0], r[0]);
+
+	p = memchr_inv(&r[1], 0, sizeof(r) - sizeof(r[0]));
+	KUNIT_EXPECT_PTR_EQ_MSG(test, p, NULL, "in test %u at %td out of bound", n, p - r);
+}
+
+static void cmdline_test_range(struct kunit *test)
+{
+	unsigned int i = 0;
+
+	do {
+		const char *str = cmdline_test_range_strings[i];
+		const int *e = cmdline_test_range_values[i];
+
+		cmdline_do_one_range_test(test, str, i, e);
+	} while (++i < ARRAY_SIZE(cmdline_test_range_strings));
+}
+
+static void cmdline_test_next_arg_quoted_value(struct kunit *test)
+{
+	char in[] = "foo=\"bar baz\" qux=1";
+	char *next, *param, *val;
+
+	next = next_arg(in, &param, &val);
+	KUNIT_EXPECT_STREQ(test, param, "foo");
+	KUNIT_ASSERT_NOT_NULL(test, val);
+	KUNIT_EXPECT_STREQ(test, val, "bar baz");
+	KUNIT_EXPECT_STREQ(test, next, "qux=1");
+
+	next = next_arg(next, &param, &val);
+	KUNIT_EXPECT_STREQ(test, param, "qux");
+	KUNIT_ASSERT_NOT_NULL(test, val);
+	KUNIT_EXPECT_STREQ(test, val, "1");
+	KUNIT_EXPECT_STREQ(test, next, "");
+}
+
+static void cmdline_test_next_arg_bare_quote_regression(struct kunit *test)
+{
+	char in[] = "foo=bar \"";
+	char *next, *param, *val;
+
+	next = next_arg(in, &param, &val);
+	KUNIT_EXPECT_STREQ(test, param, "foo");
+	KUNIT_ASSERT_NOT_NULL(test, val);
+	KUNIT_EXPECT_STREQ(test, val, "bar");
+	KUNIT_EXPECT_STREQ(test, next, "\"");
+
+	/* This hits the i == 0 quoted-token case fixed by 9847f21225c4. */
+	next = next_arg(next, &param, &val);
+	KUNIT_EXPECT_STREQ(test, param, "");
+	KUNIT_EXPECT_PTR_EQ(test, val, NULL);
+	KUNIT_EXPECT_STREQ(test, next, "");
+}
+
+static void cmdline_test_next_arg_mixed_tokens(struct kunit *test)
+{
+	char in[] = "bbb= jjj kkk=\"a=b\"";
+	char *next, *param, *val;
+
+	next = next_arg(in, &param, &val);
+	KUNIT_EXPECT_STREQ(test, param, "bbb");
+	KUNIT_ASSERT_NOT_NULL(test, val);
+	KUNIT_EXPECT_STREQ(test, val, "");
+	KUNIT_EXPECT_STREQ(test, next, "jjj kkk=\"a=b\"");
+
+	next = next_arg(next, &param, &val);
+	KUNIT_EXPECT_STREQ(test, param, "jjj");
+	KUNIT_EXPECT_NULL(test, val);
+	KUNIT_EXPECT_STREQ(test, next, "kkk=\"a=b\"");
+
+	next = next_arg(next, &param, &val);
+	KUNIT_EXPECT_STREQ(test, param, "kkk");
+	KUNIT_ASSERT_NOT_NULL(test, val);
+	KUNIT_EXPECT_STREQ(test, val, "a=b");
+	KUNIT_EXPECT_STREQ(test, next, "");
+}
+
+struct cmdline_test_memparse_entry {
+	const char *input;
+	const char *unrecognized;
+	unsigned long long result;
+};
+
+static const struct cmdline_test_memparse_entry testdata[] = {
+	{ "0",				"",	0ULL },
+	{ "1",				"",	1ULL },
+	{ "a",				"a",	0ULL },
+	{ "k",				"k",	0ULL },
+	{ "E",				"E",	0ULL },
+	{ "0xb",			"",	11ULL },
+	{ "0xz",			"x",	0ULL },
+	{ "1234",			"",	1234ULL },
+	{ "04567",			"",	2423ULL },
+	{ "0x9876",			"",	39030LL },
+	{ "05678",			"8",	375ULL },
+	{ "0xabcdefz",			"z",	11259375ULL },
+	{ "0cdba",			"c",	0ULL },
+	{ "4K",				"",	SZ_4K },
+	{ "0x10k@0xaaaabbbb",		"@",	SZ_16K },
+	{ "32M",			"",	SZ_32M },
+	{ "067m:foo",			":",	55 * SZ_1M },
+	{ "2G;bar=baz",			";",	SZ_2G },
+	{ "07gz",			"z",	7ULL * SZ_1G },
+	{ "3T+data",			"+",	3 * SZ_1T },
+	{ "04t,ro",			",",	SZ_4T },
+	{ "012p",			"",	11258999068426240ULL },
+	{ "7P,sync",			",",	7881299347898368ULL },
+	{ "0x2e",			"",	46ULL },
+	{ "2E and more",		" ",	2305843009213693952ULL },
+	{ "18446744073709551615",	"",	ULLONG_MAX },
+	{ "0xffffffffffffffff0",	"",	ULLONG_MAX },
+	{ "1111111111111111111T",	"",	ULLONG_MAX },
+	{ "222222222222222222222G",	"",	ULLONG_MAX },
+	{ "3333333333333333333333M",	"",	ULLONG_MAX },
+};
+
+static void cmdline_test_memparse(struct kunit *test)
+{
+	const struct cmdline_test_memparse_entry *e;
+	unsigned long long ret;
+	char *retptr;
+
+	for (e = testdata; e < testdata + ARRAY_SIZE(testdata); e++) {
+		ret = memparse(e->input, &retptr);
+		KUNIT_EXPECT_EQ_MSG(test, ret, e->result,
+				    "    when parsing '%s'", e->input);
+		KUNIT_EXPECT_EQ_MSG(test, *retptr, *e->unrecognized,
+				    "    when parsing '%s'", e->input);
+	}
+}
+
+static struct kunit_case cmdline_test_cases[] = {
+	KUNIT_CASE(cmdline_test_noint),
+	KUNIT_CASE(cmdline_test_lead_int),
+	KUNIT_CASE(cmdline_test_tail_int),
+	KUNIT_CASE(cmdline_test_range),
+	KUNIT_CASE(cmdline_test_next_arg_quoted_value),
+	KUNIT_CASE(cmdline_test_next_arg_bare_quote_regression),
+	KUNIT_CASE(cmdline_test_next_arg_mixed_tokens),
+	KUNIT_CASE(cmdline_test_memparse),
+	{}
+};
+
+static struct kunit_suite cmdline_test_suite = {
+	.name = "cmdline",
+	.test_cases = cmdline_test_cases,
+};
+kunit_test_suite(cmdline_test_suite);
+
+MODULE_DESCRIPTION("Test cases for API provided by cmdline.c");
+MODULE_LICENSE("GPL");