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, 330 insertions, 0 deletions

diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
new file mode 100644
index 000000000..f2cbc8e5b
--- /dev/null
+++ b/tools/testing/radix-tree/main.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <assert.h>
+#include <limits.h>
+
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+
+#include "test.h"
+#include "regression.h"
+
+void __gang_check(unsigned long middle, long down, long up, int chunk, int hop)
+{
+	long idx;
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	middle = 1 << 30;
+
+	for (idx = -down; idx < up; idx++)
+		item_insert(&tree, middle + idx);
+
+	item_check_absent(&tree, middle - down - 1);
+	for (idx = -down; idx < up; idx++)
+		item_check_present(&tree, middle + idx);
+	item_check_absent(&tree, middle + up);
+
+	if (chunk > 0) {
+		item_gang_check_present(&tree, middle - down, up + down,
+				chunk, hop);
+		item_full_scan(&tree, middle - down, down + up, chunk);
+	}
+	item_kill_tree(&tree);
+}
+
+void gang_check(void)
+{
+	__gang_check(1UL << 30, 128, 128, 35, 2);
+	__gang_check(1UL << 31, 128, 128, 32, 32);
+	__gang_check(1UL << 31, 128, 128, 32, 100);
+	__gang_check(1UL << 31, 128, 128, 17, 7);
+	__gang_check(0xffff0000UL, 0, 65536, 17, 7);
+	__gang_check(0xfffffffeUL, 1, 1, 17, 7);
+}
+
+void __big_gang_check(void)
+{
+	unsigned long start;
+	int wrapped = 0;
+
+	start = 0;
+	do {
+		unsigned long old_start;
+
+//		printf("0x%08lx\n", start);
+		__gang_check(start, rand() % 113 + 1, rand() % 71,
+				rand() % 157, rand() % 91 + 1);
+		old_start = start;
+		start += rand() % 1000000;
+		start %= 1ULL << 33;
+		if (start < old_start)
+			wrapped = 1;
+	} while (!wrapped);
+}
+
+void big_gang_check(bool long_run)
+{
+	int i;
+
+	for (i = 0; i < (long_run ? 1000 : 3); i++) {
+		__big_gang_check();
+		printv(2, "%d ", i);
+		fflush(stdout);
+	}
+}
+
+void add_and_check(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert(&tree, 44);
+	item_check_present(&tree, 44);
+	item_check_absent(&tree, 43);
+	item_kill_tree(&tree);
+}
+
+void dynamic_height_check(void)
+{
+	int i;
+	RADIX_TREE(tree, GFP_KERNEL);
+	tree_verify_min_height(&tree, 0);
+
+	item_insert(&tree, 42);
+	tree_verify_min_height(&tree, 42);
+
+	item_insert(&tree, 1000000);
+	tree_verify_min_height(&tree, 1000000);
+
+	assert(item_delete(&tree, 1000000));
+	tree_verify_min_height(&tree, 42);
+
+	assert(item_delete(&tree, 42));
+	tree_verify_min_height(&tree, 0);
+
+	for (i = 0; i < 1000; i++) {
+		item_insert(&tree, i);
+		tree_verify_min_height(&tree, i);
+	}
+
+	i--;
+	for (;;) {
+		assert(item_delete(&tree, i));
+		if (i == 0) {
+			tree_verify_min_height(&tree, 0);
+			break;
+		}
+		i--;
+		tree_verify_min_height(&tree, i);
+	}
+
+	item_kill_tree(&tree);
+}
+
+void check_copied_tags(struct radix_tree_root *tree, unsigned long start, unsigned long end, unsigned long *idx, int count, int fromtag, int totag)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+/*		if (i % 1000 == 0)
+			putchar('.'); */
+		if (idx[i] < start || idx[i] > end) {
+			if (item_tag_get(tree, idx[i], totag)) {
+				printv(2, "%lu-%lu: %lu, tags %d-%d\n", start,
+				       end, idx[i], item_tag_get(tree, idx[i],
+								 fromtag),
+				       item_tag_get(tree, idx[i], totag));
+			}
+			assert(!item_tag_get(tree, idx[i], totag));
+			continue;
+		}
+		if (item_tag_get(tree, idx[i], fromtag) ^
+			item_tag_get(tree, idx[i], totag)) {
+			printv(2, "%lu-%lu: %lu, tags %d-%d\n", start, end,
+			       idx[i], item_tag_get(tree, idx[i], fromtag),
+			       item_tag_get(tree, idx[i], totag));
+		}
+		assert(!(item_tag_get(tree, idx[i], fromtag) ^
+			 item_tag_get(tree, idx[i], totag)));
+	}
+}
+
+#define ITEMS 50000
+
+void copy_tag_check(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	unsigned long idx[ITEMS];
+	unsigned long start, end, count = 0, tagged, cur, tmp;
+	int i;
+
+//	printf("generating radix tree indices...\n");
+	start = rand();
+	end = rand();
+	if (start > end && (rand() % 10)) {
+		cur = start;
+		start = end;
+		end = cur;
+	}
+	/* Specifically create items around the start and the end of the range
+	 * with high probability to check for off by one errors */
+	cur = rand();
+	if (cur & 1) {
+		item_insert(&tree, start);
+		if (cur & 2) {
+			if (start <= end)
+				count++;
+			item_tag_set(&tree, start, 0);
+		}
+	}
+	if (cur & 4) {
+		item_insert(&tree, start-1);
+		if (cur & 8)
+			item_tag_set(&tree, start-1, 0);
+	}
+	if (cur & 16) {
+		item_insert(&tree, end);
+		if (cur & 32) {
+			if (start <= end)
+				count++;
+			item_tag_set(&tree, end, 0);
+		}
+	}
+	if (cur & 64) {
+		item_insert(&tree, end+1);
+		if (cur & 128)
+			item_tag_set(&tree, end+1, 0);
+	}
+
+	for (i = 0; i < ITEMS; i++) {
+		do {
+			idx[i] = rand();
+		} while (item_lookup(&tree, idx[i]));
+
+		item_insert(&tree, idx[i]);
+		if (rand() & 1) {
+			item_tag_set(&tree, idx[i], 0);
+			if (idx[i] >= start && idx[i] <= end)
+				count++;
+		}
+/*		if (i % 1000 == 0)
+			putchar('.'); */
+	}
+
+//	printf("\ncopying tags...\n");
+	tagged = tag_tagged_items(&tree, start, end, ITEMS, XA_MARK_0, XA_MARK_1);
+
+//	printf("checking copied tags\n");
+	assert(tagged == count);
+	check_copied_tags(&tree, start, end, idx, ITEMS, 0, 1);
+
+	/* Copy tags in several rounds */
+//	printf("\ncopying tags...\n");
+	tmp = rand() % (count / 10 + 2);
+	tagged = tag_tagged_items(&tree, start, end, tmp, XA_MARK_0, XA_MARK_2);
+	assert(tagged == count);
+
+//	printf("%lu %lu %lu\n", tagged, tmp, count);
+//	printf("checking copied tags\n");
+	check_copied_tags(&tree, start, end, idx, ITEMS, 0, 2);
+	verify_tag_consistency(&tree, 0);
+	verify_tag_consistency(&tree, 1);
+	verify_tag_consistency(&tree, 2);
+//	printf("\n");
+	item_kill_tree(&tree);
+}
+
+static void single_thread_tests(bool long_run)
+{
+	int i;
+
+	printv(1, "starting single_thread_tests: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	multiorder_checks();
+	rcu_barrier();
+	printv(2, "after multiorder_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	tag_check();
+	rcu_barrier();
+	printv(2, "after tag_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	gang_check();
+	rcu_barrier();
+	printv(2, "after gang_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	add_and_check();
+	rcu_barrier();
+	printv(2, "after add_and_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	dynamic_height_check();
+	rcu_barrier();
+	printv(2, "after dynamic_height_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	idr_checks();
+	ida_tests();
+	rcu_barrier();
+	printv(2, "after idr_checks: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	big_gang_check(long_run);
+	rcu_barrier();
+	printv(2, "after big_gang_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	for (i = 0; i < (long_run ? 2000 : 3); i++) {
+		copy_tag_check();
+		printv(2, "%d ", i);
+		fflush(stdout);
+	}
+	rcu_barrier();
+	printv(2, "after copy_tag_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+}
+
+int main(int argc, char **argv)
+{
+	bool long_run = false;
+	int opt;
+	unsigned int seed = time(NULL);
+
+	while ((opt = getopt(argc, argv, "ls:v")) != -1) {
+		if (opt == 'l')
+			long_run = true;
+		else if (opt == 's')
+			seed = strtoul(optarg, NULL, 0);
+		else if (opt == 'v')
+			test_verbose++;
+	}
+
+	printf("random seed %u\n", seed);
+	srand(seed);
+
+	printf("running tests\n");
+
+	rcu_register_thread();
+	radix_tree_init();
+
+	xarray_tests();
+	regression1_test();
+	regression2_test();
+	regression3_test();
+	regression4_test();
+	iteration_test(0, 10 + 90 * long_run);
+	iteration_test(7, 10 + 90 * long_run);
+	iteration_test2(10 + 90 * long_run);
+	single_thread_tests(long_run);
+
+	/* Free any remaining preallocated nodes */
+	radix_tree_cpu_dead(0);
+
+	benchmark();
+
+	rcu_barrier();
+	printv(2, "after rcu_barrier: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	rcu_unregister_thread();
+
+	printf("tests completed\n");
+
+	exit(0);
+}