[RFC PATCH 10/10] KVM: selftests: Test KVM exit behavior for private memory/access

[Ackerley Tng <ackerleytng@google.com>]

"Testing private access when memslot gets deleted" tests the behavior
of KVM when a private memslot gets deleted while the VM is using the
private memslot. When KVM looks up the deleted (slot = NULL) memslot,
KVM should exit to userspace with KVM_EXIT_MEMORY_FAULT.

In the second test, upon a private access to non-private memslot, KVM
should also exit to userspace with KVM_EXIT_MEMORY_FAULT.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../kvm/x86_64/private_mem_kvm_exits_test.c   | 124 ++++++++++++++++++
 2 files changed, 125 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index bafee3c43b2e..0ad588852a1d 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -80,6 +80,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/nested_exceptions_test
 TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
 TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test
 TEST_GEN_PROGS_x86_64 += x86_64/private_mem_conversions_test
+TEST_GEN_PROGS_x86_64 += x86_64/private_mem_kvm_exits_test
 TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id
 TEST_GEN_PROGS_x86_64 += x86_64/set_sregs_test
 TEST_GEN_PROGS_x86_64 += x86_64/smaller_maxphyaddr_emulation_test
diff --git a/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c b/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c
new file mode 100644
index 000000000000..c8667dfbbf0a
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022, Google LLC.
+ */
+#include "kvm_util_base.h"
+#include <linux/kvm.h>
+#include <pthread.h>
+#include <stdint.h>
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+/* Arbitrarily selected to avoid overlaps with anything else */
+#define EXITS_TEST_GVA 0xc0000000
+#define EXITS_TEST_GPA EXITS_TEST_GVA
+#define EXITS_TEST_NPAGES 1
+#define EXITS_TEST_SIZE (EXITS_TEST_NPAGES * PAGE_SIZE)
+#define EXITS_TEST_SLOT 10
+
+static uint64_t guest_repeatedly_read(void)
+{
+	volatile uint64_t value;
+
+	while (true)
+		value = *((uint64_t *) EXITS_TEST_GVA);
+
+	return value;
+}
+
+static uint32_t run_vcpu_get_exit_reason(struct kvm_vcpu *vcpu)
+{
+	vcpu_run(vcpu);
+
+	return vcpu->run->exit_reason;
+}
+
+const struct vm_shape protected_vm_shape = {
+	.mode = VM_MODE_DEFAULT,
+	.type = KVM_X86_PROTECTED_VM,
+};
+
+static void test_private_access_memslot_deleted(void)
+{
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+	pthread_t vm_thread;
+	void *thread_return;
+	uint32_t exit_reason;
+
+	vm = vm_create_shape_with_one_vcpu(protected_vm_shape, &vcpu,
+					   guest_repeatedly_read);
+
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+				    EXITS_TEST_GPA, EXITS_TEST_SLOT,
+				    EXITS_TEST_NPAGES,
+				    KVM_MEM_PRIVATE);
+
+	virt_map(vm, EXITS_TEST_GVA, EXITS_TEST_GPA, EXITS_TEST_NPAGES);
+
+	/* Request to access page privately */
+	vm_mem_map_shared_or_private(vm, EXITS_TEST_GPA, EXITS_TEST_SIZE, false);
+
+	pr_info("Testing private access when memslot gets deleted\n");
+
+	pthread_create(&vm_thread, NULL,
+		       (void *(*)(void *))run_vcpu_get_exit_reason,
+		       (void *)vcpu);
+
+	vm_mem_region_delete(vm, EXITS_TEST_SLOT);
+
+	pthread_join(vm_thread, &thread_return);
+	exit_reason = (uint32_t)(uint64_t)thread_return;
+
+	ASSERT_EQ(exit_reason, KVM_EXIT_MEMORY_FAULT);
+	ASSERT_EQ(vcpu->run->memory.flags, KVM_MEMORY_EXIT_FLAG_PRIVATE);
+	ASSERT_EQ(vcpu->run->memory.gpa, EXITS_TEST_GPA);
+	ASSERT_EQ(vcpu->run->memory.size, EXITS_TEST_SIZE);
+
+	pr_info("\t ... PASSED\n");
+
+	kvm_vm_free(vm);
+}
+
+static void test_private_access_memslot_not_private(void)
+{
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+	uint32_t exit_reason;
+
+	vm = vm_create_shape_with_one_vcpu(protected_vm_shape, &vcpu,
+					   guest_repeatedly_read);
+
+	/* Add a non-private memslot (flags = 0) */
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+				    EXITS_TEST_GPA, EXITS_TEST_SLOT,
+				    EXITS_TEST_NPAGES, 0);
+
+	virt_map(vm, EXITS_TEST_GVA, EXITS_TEST_GPA, EXITS_TEST_NPAGES);
+
+	/* Request to access page privately */
+	vm_set_memory_attributes(vm, EXITS_TEST_GPA, EXITS_TEST_SIZE,
+				 KVM_MEMORY_ATTRIBUTE_PRIVATE);
+
+	pr_info("Testing private access to non-private memslot\n");
+
+	exit_reason = run_vcpu_get_exit_reason(vcpu);
+
+	ASSERT_EQ(exit_reason, KVM_EXIT_MEMORY_FAULT);
+	ASSERT_EQ(vcpu->run->memory.flags, KVM_MEMORY_EXIT_FLAG_PRIVATE);
+	ASSERT_EQ(vcpu->run->memory.gpa, EXITS_TEST_GPA);
+	ASSERT_EQ(vcpu->run->memory.size, EXITS_TEST_SIZE);
+
+	pr_info("\t ... PASSED\n");
+
+	kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+	TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_PROTECTED_VM));
+
+	test_private_access_memslot_deleted();
+	test_private_access_memslot_not_private();
+}
-- 
2.40.0.rc2.332.ga46443480c-goog