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>

4 files changed, 143 insertions, 0 deletions

diff --git a/tools/testing/rbtree/Makefile b/tools/testing/rbtree/Makefile
new file mode 100644
index 000000000..d7bbae2af
--- /dev/null
+++ b/tools/testing/rbtree/Makefile
@@ -0,0 +1,33 @@
+# SPDX-License-Identifier: GPL-2.0
+
+.PHONY: clean
+
+TARGETS = rbtree_test interval_tree_test
+OFILES = $(SHARED_OFILES) rbtree-shim.o interval_tree-shim.o maple-shim.o
+DEPS = ../../../include/linux/rbtree.h \
+	../../../include/linux/rbtree_types.h \
+	../../../include/linux/rbtree_augmented.h \
+	../../../include/linux/interval_tree.h \
+	../../../include/linux/interval_tree_generic.h \
+	../../../lib/rbtree.c \
+	../../../lib/interval_tree.c
+
+targets: $(TARGETS)
+
+include ../shared/shared.mk
+
+ifeq ($(DEBUG), 1)
+	CFLAGS += -g
+endif
+
+$(TARGETS):	$(OFILES)
+
+rbtree-shim.o: $(DEPS)
+rbtree_test.o:  ../../../lib/rbtree_test.c
+interval_tree-shim.o: $(DEPS)
+interval_tree-shim.o: CFLAGS += -DCONFIG_INTERVAL_TREE_SPAN_ITER
+interval_tree_test.o: 	../../../lib/interval_tree_test.c
+interval_tree_test.o: CFLAGS += -DCONFIG_INTERVAL_TREE_SPAN_ITER
+
+clean:
+	$(RM) $(TARGETS) *.o radix-tree.c idr.c generated/*
diff --git a/tools/testing/rbtree/interval_tree_test.c b/tools/testing/rbtree/interval_tree_test.c
new file mode 100644
index 000000000..49bc5b534
--- /dev/null
+++ b/tools/testing/rbtree/interval_tree_test.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * interval_tree.c: Userspace Interval Tree test-suite
+ * Copyright (c) 2025 Wei Yang <richard.weiyang@gmail.com>
+ */
+#include <linux/math64.h>
+#include <linux/kern_levels.h>
+#include "shared.h"
+#include "maple-shared.h"
+
+#include "../../../lib/interval_tree_test.c"
+
+int usage(void)
+{
+	fprintf(stderr, "Userland interval tree test cases\n");
+	fprintf(stderr, "  -n: Number of nodes in the interval tree\n");
+	fprintf(stderr, "  -p: Number of iterations modifying the tree\n");
+	fprintf(stderr, "  -q: Number of searches to the interval tree\n");
+	fprintf(stderr, "  -s: Number of iterations searching the tree\n");
+	fprintf(stderr, "  -a: Searches will iterate all nodes in the tree\n");
+	fprintf(stderr, "  -m: Largest value for the interval's endpoint\n");
+	fprintf(stderr, "  -r: Random seed\n");
+	exit(-1);
+}
+
+void interval_tree_tests(void)
+{
+	interval_tree_test_init();
+	interval_tree_test_exit();
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "n:p:q:s:am:r:")) != -1) {
+		if (opt == 'n')
+			nnodes = strtoul(optarg, NULL, 0);
+		else if (opt == 'p')
+			perf_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'q')
+			nsearches = strtoul(optarg, NULL, 0);
+		else if (opt == 's')
+			search_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'a')
+			search_all = true;
+		else if (opt == 'm')
+			max_endpoint = strtoul(optarg, NULL, 0);
+		else if (opt == 'r')
+			seed = strtoul(optarg, NULL, 0);
+		else
+			usage();
+	}
+
+	maple_tree_init();
+	interval_tree_tests();
+	return 0;
+}
diff --git a/tools/testing/rbtree/rbtree_test.c b/tools/testing/rbtree/rbtree_test.c
new file mode 100644
index 000000000..585c970f6
--- /dev/null
+++ b/tools/testing/rbtree/rbtree_test.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rbtree_test.c: Userspace Red Black Tree test-suite
+ * Copyright (c) 2025 Wei Yang <richard.weiyang@gmail.com>
+ */
+#include <linux/init.h>
+#include <linux/math64.h>
+#include <linux/kern_levels.h>
+#include "shared.h"
+
+#include "../../../lib/rbtree_test.c"
+
+int usage(void)
+{
+	fprintf(stderr, "Userland rbtree test cases\n");
+	fprintf(stderr, "  -n: Number of nodes in the rb-tree\n");
+	fprintf(stderr, "  -p: Number of iterations modifying the rb-tree\n");
+	fprintf(stderr, "  -c: Number of iterations modifying and verifying the rb-tree\n");
+	fprintf(stderr, "  -r: Random seed\n");
+	exit(-1);
+}
+
+void rbtree_tests(void)
+{
+	rbtree_test_init();
+	rbtree_test_exit();
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "n:p:c:r:")) != -1) {
+		if (opt == 'n')
+			nnodes = strtoul(optarg, NULL, 0);
+		else if (opt == 'p')
+			perf_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'c')
+			check_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'r')
+			seed = strtoul(optarg, NULL, 0);
+		else
+			usage();
+	}
+
+	rbtree_tests();
+	return 0;
+}
diff --git a/tools/testing/rbtree/test.h b/tools/testing/rbtree/test.h
new file mode 100644
index 000000000..f1f1b545b
--- /dev/null
+++ b/tools/testing/rbtree/test.h
@@ -0,0 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+void rbtree_tests(void);
+void interval_tree_tests(void);