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/kunit/assert.c b/lib/kunit/assert.c
new file mode 100644
index 000000000..4c751ad85
--- /dev/null
+++ b/lib/kunit/assert.c
@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Assertion and expectation serialization API.
+ *
+ * Copyright (C) 2019, Google LLC.
+ * Author: Brendan Higgins <brendanhiggins@google.com>
+ */
+#include <kunit/assert.h>
+#include <kunit/test.h>
+#include <kunit/visibility.h>
+
+#include "string-stream.h"
+
+void kunit_assert_prologue(const struct kunit_loc *loc,
+			   enum kunit_assert_type type,
+			      struct string_stream *stream)
+{
+	const char *expect_or_assert = NULL;
+
+	switch (type) {
+	case KUNIT_EXPECTATION:
+		expect_or_assert = "EXPECTATION";
+		break;
+	case KUNIT_ASSERTION:
+		expect_or_assert = "ASSERTION";
+		break;
+	}
+
+	string_stream_add(stream, "%s FAILED at %s:%d\n",
+			  expect_or_assert, loc->file, loc->line);
+}
+EXPORT_SYMBOL_GPL(kunit_assert_prologue);
+
+VISIBLE_IF_KUNIT
+void kunit_assert_print_msg(const struct va_format *message,
+			    struct string_stream *stream)
+{
+	if (message->fmt)
+		string_stream_add(stream, "\n%pV", message);
+}
+
+void kunit_fail_assert_format(const struct kunit_assert *assert,
+			      const struct va_format *message,
+			      struct string_stream *stream)
+{
+	string_stream_add(stream, "%pV", message);
+}
+EXPORT_SYMBOL_GPL(kunit_fail_assert_format);
+
+void kunit_unary_assert_format(const struct kunit_assert *assert,
+			       const struct va_format *message,
+			       struct string_stream *stream)
+{
+	const struct kunit_unary_assert *unary_assert;
+
+	unary_assert = container_of(assert, struct kunit_unary_assert, assert);
+
+	if (unary_assert->expected_true)
+		string_stream_add(stream,
+				  KUNIT_SUBTEST_INDENT "Expected %s to be true, but is false\n",
+				  unary_assert->condition);
+	else
+		string_stream_add(stream,
+				  KUNIT_SUBTEST_INDENT "Expected %s to be false, but is true\n",
+				  unary_assert->condition);
+	kunit_assert_print_msg(message, stream);
+}
+EXPORT_SYMBOL_GPL(kunit_unary_assert_format);
+
+void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
+				     const struct va_format *message,
+				     struct string_stream *stream)
+{
+	const struct kunit_ptr_not_err_assert *ptr_assert;
+
+	ptr_assert = container_of(assert, struct kunit_ptr_not_err_assert,
+				  assert);
+
+	if (!ptr_assert->value) {
+		string_stream_add(stream,
+				  KUNIT_SUBTEST_INDENT "Expected %s is not null, but is\n",
+				  ptr_assert->text);
+	} else if (IS_ERR(ptr_assert->value)) {
+		string_stream_add(stream,
+				  KUNIT_SUBTEST_INDENT "Expected %s is not error, but is: %ld\n",
+				  ptr_assert->text,
+				  PTR_ERR(ptr_assert->value));
+	}
+	kunit_assert_print_msg(message, stream);
+}
+EXPORT_SYMBOL_GPL(kunit_ptr_not_err_assert_format);
+
+/* Checks if `text` is a literal representing `value`, e.g. "5" and 5 */
+VISIBLE_IF_KUNIT bool is_literal(const char *text, long long value)
+{
+	char *buffer;
+	int len;
+	bool ret;
+
+	len = snprintf(NULL, 0, "%lld", value);
+	if (strlen(text) != len)
+		return false;
+
+	buffer = kmalloc(len+1, GFP_KERNEL);
+	if (!buffer)
+		return false;
+
+	snprintf(buffer, len+1, "%lld", value);
+	ret = strncmp(buffer, text, len) == 0;
+
+	kfree(buffer);
+
+	return ret;
+}
+
+void kunit_binary_assert_format(const struct kunit_assert *assert,
+				const struct va_format *message,
+				struct string_stream *stream)
+{
+	const struct kunit_binary_assert *binary_assert;
+
+	binary_assert = container_of(assert, struct kunit_binary_assert,
+				     assert);
+
+	string_stream_add(stream,
+			  KUNIT_SUBTEST_INDENT "Expected %s %s %s, but\n",
+			  binary_assert->text->left_text,
+			  binary_assert->text->operation,
+			  binary_assert->text->right_text);
+	if (!is_literal(binary_assert->text->left_text, binary_assert->left_value))
+		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld (0x%llx)\n",
+				  binary_assert->text->left_text,
+				  binary_assert->left_value,
+				  binary_assert->left_value);
+	if (!is_literal(binary_assert->text->right_text, binary_assert->right_value))
+		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld (0x%llx)",
+				  binary_assert->text->right_text,
+				  binary_assert->right_value,
+				  binary_assert->right_value);
+	kunit_assert_print_msg(message, stream);
+}
+EXPORT_SYMBOL_GPL(kunit_binary_assert_format);
+
+void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
+				    const struct va_format *message,
+				    struct string_stream *stream)
+{
+	const struct kunit_binary_ptr_assert *binary_assert;
+
+	binary_assert = container_of(assert, struct kunit_binary_ptr_assert,
+				     assert);
+
+	string_stream_add(stream,
+			  KUNIT_SUBTEST_INDENT "Expected %s %s %s, but\n",
+			  binary_assert->text->left_text,
+			  binary_assert->text->operation,
+			  binary_assert->text->right_text);
+	string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %px\n",
+			  binary_assert->text->left_text,
+			  binary_assert->left_value);
+	string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %px",
+			  binary_assert->text->right_text,
+			  binary_assert->right_value);
+	kunit_assert_print_msg(message, stream);
+}
+EXPORT_SYMBOL_GPL(kunit_binary_ptr_assert_format);
+
+/* Checks if KUNIT_EXPECT_STREQ() args were string literals.
+ * Note: `text` will have ""s where as `value` will not.
+ */
+VISIBLE_IF_KUNIT bool is_str_literal(const char *text, const char *value)
+{
+	int len;
+
+	len = strlen(text);
+	if (len < 2)
+		return false;
+	if (text[0] != '\"' || text[len - 1] != '\"')
+		return false;
+
+	return strncmp(text + 1, value, len - 2) == 0;
+}
+
+void kunit_binary_str_assert_format(const struct kunit_assert *assert,
+				    const struct va_format *message,
+				    struct string_stream *stream)
+{
+	const struct kunit_binary_str_assert *binary_assert;
+
+	binary_assert = container_of(assert, struct kunit_binary_str_assert,
+				     assert);
+
+	string_stream_add(stream,
+			  KUNIT_SUBTEST_INDENT "Expected %s %s %s, but\n",
+			  binary_assert->text->left_text,
+			  binary_assert->text->operation,
+			  binary_assert->text->right_text);
+	if (!is_str_literal(binary_assert->text->left_text, binary_assert->left_value))
+		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == \"%s\"\n",
+				  binary_assert->text->left_text,
+				  binary_assert->left_value);
+	if (!is_str_literal(binary_assert->text->right_text, binary_assert->right_value))
+		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == \"%s\"",
+				  binary_assert->text->right_text,
+				  binary_assert->right_value);
+	kunit_assert_print_msg(message, stream);
+}
+EXPORT_SYMBOL_GPL(kunit_binary_str_assert_format);
+
+/* Adds a hexdump of a buffer to a string_stream comparing it with
+ * a second buffer. The different bytes are marked with <>.
+ */
+VISIBLE_IF_KUNIT
+void kunit_assert_hexdump(struct string_stream *stream,
+			  const void *buf,
+			  const void *compared_buf,
+			  const size_t len)
+{
+	size_t i;
+	const u8 *buf1 = buf;
+	const u8 *buf2 = compared_buf;
+
+	string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT);
+
+	for (i = 0; i < len; ++i) {
+		if (!(i % 16) && i)
+			string_stream_add(stream, "\n" KUNIT_SUBSUBTEST_INDENT);
+
+		if (buf1[i] != buf2[i])
+			string_stream_add(stream, "<%02x>", buf1[i]);
+		else
+			string_stream_add(stream, " %02x ", buf1[i]);
+	}
+}
+
+void kunit_mem_assert_format(const struct kunit_assert *assert,
+			     const struct va_format *message,
+			     struct string_stream *stream)
+{
+	const struct kunit_mem_assert *mem_assert;
+
+	mem_assert = container_of(assert, struct kunit_mem_assert,
+				  assert);
+
+	if (!mem_assert->left_value) {
+		string_stream_add(stream,
+				  KUNIT_SUBTEST_INDENT "Expected %s is not null, but is\n",
+				  mem_assert->text->left_text);
+	} else if (!mem_assert->right_value) {
+		string_stream_add(stream,
+				  KUNIT_SUBTEST_INDENT "Expected %s is not null, but is\n",
+				  mem_assert->text->right_text);
+	} else {
+		string_stream_add(stream,
+				KUNIT_SUBTEST_INDENT "Expected %s %s %s, but\n",
+				mem_assert->text->left_text,
+				mem_assert->text->operation,
+				mem_assert->text->right_text);
+
+		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s ==\n",
+				mem_assert->text->left_text);
+		kunit_assert_hexdump(stream, mem_assert->left_value,
+					mem_assert->right_value, mem_assert->size);
+
+		string_stream_add(stream, "\n");
+
+		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s ==\n",
+				mem_assert->text->right_text);
+		kunit_assert_hexdump(stream, mem_assert->right_value,
+					mem_assert->left_value, mem_assert->size);
+
+		kunit_assert_print_msg(message, stream);
+	}
+}
+EXPORT_SYMBOL_GPL(kunit_mem_assert_format);