[V1 PATCH 6/6] KVM: selftests: x86: Add selftest for private memory

[Vishal Annapurve]

Add a selftest to exercise implicit/explicit conversion functionality
within KVM and verify:
1) Shared memory is visible to host userspace after conversion
2) Private memory is not visible to host userspace before/after conversion
3) Host userspace and guest can communicate over shared memory

Signed-off-by: Vishal Annapurve <vannapurve@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/x86_64/private_mem_test.c   | 190 ++++++++++++++++++
 3 files changed, 192 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/x86_64/private_mem_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 2f0d705db9db..77b79b740424 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -32,6 +32,7 @@
 /x86_64/nested_exceptions_test
 /x86_64/nx_huge_pages_test
 /x86_64/platform_info_test
+/x86_64/private_mem_test
 /x86_64/pmu_event_filter_test
 /x86_64/set_boot_cpu_id
 /x86_64/set_sregs_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 57385ad58527..d1fa27a58f8f 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -95,6 +95,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/monitor_mwait_test
 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_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/smm_test
diff --git a/tools/testing/selftests/kvm/x86_64/private_mem_test.c b/tools/testing/selftests/kvm/x86_64/private_mem_test.c
new file mode 100644
index 000000000000..a93f9e5d15a8
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/private_mem_test.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * tools/testing/selftests/kvm/lib/kvm_util.c
+ *
+ * Copyright (C) 2022, Google LLC.
+ */
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <limits.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/kvm_para.h>
+#include <linux/memfd.h>
+
+#include <test_util.h>
+#include <kvm_util.h>
+#include <private_mem.h>
+#include <processor.h>
+
+#define TEST_AREA_SLOT		10
+#define TEST_AREA_GPA		0xC0000000
+#define TEST_AREA_SIZE		(2 * 1024 * 1024)
+#define GUEST_TEST_MEM_OFFSET	(1 * 1024 * 1024)
+#define GUEST_TEST_MEM_SIZE	(10 * 4096)
+
+#define VM_STAGE_PROCESSED(x)	pr_info("Processed stage %s\n", #x)
+
+#define TEST_MEM_DATA_PATTERN1	0x66
+#define TEST_MEM_DATA_PATTERN2	0x99
+#define TEST_MEM_DATA_PATTERN3	0x33
+#define TEST_MEM_DATA_PATTERN4	0xaa
+#define TEST_MEM_DATA_PATTERN5	0x12
+
+static bool verify_mem_contents(void *mem, uint32_t size, uint8_t pattern)
+{
+	uint8_t *buf = (uint8_t *)mem;
+
+	for (uint32_t i = 0; i < size; i++) {
+		if (buf[i] != pattern)
+			return false;
+	}
+
+	return true;
+}
+
+static void populate_test_area(void *test_area_base, uint64_t pattern)
+{
+	memset(test_area_base, pattern, TEST_AREA_SIZE);
+}
+
+static void populate_guest_test_mem(void *guest_test_mem, uint64_t pattern)
+{
+	memset(guest_test_mem, pattern, GUEST_TEST_MEM_SIZE);
+}
+
+static bool verify_test_area(void *test_area_base, uint64_t area_pattern,
+	uint64_t guest_pattern)
+{
+	void *guest_test_mem = test_area_base + GUEST_TEST_MEM_OFFSET;
+	void *test_area2_base = guest_test_mem + GUEST_TEST_MEM_SIZE;
+	uint64_t test_area2_size = (TEST_AREA_SIZE - (GUEST_TEST_MEM_OFFSET +
+			GUEST_TEST_MEM_SIZE));
+
+	return (verify_mem_contents(test_area_base, GUEST_TEST_MEM_OFFSET, area_pattern) &&
+		verify_mem_contents(guest_test_mem, GUEST_TEST_MEM_SIZE, guest_pattern) &&
+		verify_mem_contents(test_area2_base, test_area2_size, area_pattern));
+}
+
+#define GUEST_STARTED			0
+#define GUEST_PRIVATE_MEM_POPULATED	1
+#define GUEST_SHARED_MEM_POPULATED	2
+#define GUEST_PRIVATE_MEM_POPULATED2	3
+
+/*
+ * Run memory conversion tests with explicit conversion:
+ * Execute KVM hypercall to map/unmap gpa range which will cause userspace exit
+ * to back/unback private memory. Subsequent accesses by guest to the gpa range
+ * will not cause exit to userspace.
+ *
+ * Test memory conversion scenarios with following steps:
+ * 1) Access private memory using private access and verify that memory contents
+ *   are not visible to userspace.
+ * 2) Convert memory to shared using explicit conversions and ensure that
+ *   userspace is able to access the shared regions.
+ * 3) Convert memory back to private using explicit conversions and ensure that
+ *   userspace is again not able to access converted private regions.
+ */
+static void guest_conv_test_fn(void)
+{
+	void *test_area_base = (void *)TEST_AREA_GPA;
+	void *guest_test_mem = (void *)(TEST_AREA_GPA + GUEST_TEST_MEM_OFFSET);
+	uint64_t guest_test_size = GUEST_TEST_MEM_SIZE;
+
+	GUEST_SYNC(GUEST_STARTED);
+
+	populate_test_area(test_area_base, TEST_MEM_DATA_PATTERN1);
+	GUEST_SYNC(GUEST_PRIVATE_MEM_POPULATED);
+	GUEST_ASSERT(verify_test_area(test_area_base, TEST_MEM_DATA_PATTERN1,
+		TEST_MEM_DATA_PATTERN1));
+
+	kvm_hypercall_map_shared((uint64_t)guest_test_mem, guest_test_size);
+
+	populate_guest_test_mem(guest_test_mem, TEST_MEM_DATA_PATTERN2);
+
+	GUEST_SYNC(GUEST_SHARED_MEM_POPULATED);
+	GUEST_ASSERT(verify_test_area(test_area_base, TEST_MEM_DATA_PATTERN1,
+		TEST_MEM_DATA_PATTERN5));
+
+	kvm_hypercall_map_private((uint64_t)guest_test_mem, guest_test_size);
+
+	populate_guest_test_mem(guest_test_mem, TEST_MEM_DATA_PATTERN3);
+	GUEST_SYNC(GUEST_PRIVATE_MEM_POPULATED2);
+
+	GUEST_ASSERT(verify_test_area(test_area_base, TEST_MEM_DATA_PATTERN1,
+		TEST_MEM_DATA_PATTERN3));
+	GUEST_DONE();
+}
+
+static void conv_test_ioexit_fn(struct kvm_vm *vm, uint32_t uc_arg1)
+{
+	void *test_area_hva = addr_gpa2hva(vm, TEST_AREA_GPA);
+	void *guest_test_mem_hva = (test_area_hva + GUEST_TEST_MEM_OFFSET);
+	uint64_t guest_mem_gpa = (TEST_AREA_GPA + GUEST_TEST_MEM_OFFSET);
+	uint64_t guest_test_size = GUEST_TEST_MEM_SIZE;
+
+	switch (uc_arg1) {
+	case GUEST_STARTED:
+		populate_test_area(test_area_hva, TEST_MEM_DATA_PATTERN4);
+		VM_STAGE_PROCESSED(GUEST_STARTED);
+		break;
+	case GUEST_PRIVATE_MEM_POPULATED:
+		TEST_ASSERT(verify_test_area(test_area_hva, TEST_MEM_DATA_PATTERN4,
+				TEST_MEM_DATA_PATTERN4), "failed");
+		VM_STAGE_PROCESSED(GUEST_PRIVATE_MEM_POPULATED);
+		break;
+	case GUEST_SHARED_MEM_POPULATED:
+		TEST_ASSERT(verify_test_area(test_area_hva, TEST_MEM_DATA_PATTERN4,
+				TEST_MEM_DATA_PATTERN2), "failed");
+		populate_guest_test_mem(guest_test_mem_hva, TEST_MEM_DATA_PATTERN5);
+		VM_STAGE_PROCESSED(GUEST_SHARED_MEM_POPULATED);
+		break;
+	case GUEST_PRIVATE_MEM_POPULATED2:
+		TEST_ASSERT(verify_test_area(test_area_hva, TEST_MEM_DATA_PATTERN4,
+				TEST_MEM_DATA_PATTERN5), "failed");
+		VM_STAGE_PROCESSED(GUEST_PRIVATE_MEM_POPULATED2);
+		break;
+	default:
+		TEST_FAIL("Unknown stage %d\n", uc_arg1);
+		break;
+	}
+}
+
+static void execute_memory_conversion_test(enum vm_mem_backing_src_type test_mem_src)
+{
+	struct vm_setup_info info;
+	struct test_setup_info *test_info = &info.test_info;
+
+	info.test_mem_src = test_mem_src;
+	test_info->test_area_gpa = TEST_AREA_GPA;
+	test_info->test_area_size = TEST_AREA_SIZE;
+	test_info->test_area_slot = TEST_AREA_SLOT;
+	info.ioexit_cb = conv_test_ioexit_fn;
+
+	info.guest_fn = guest_conv_test_fn;
+	execute_vm_with_private_test_mem(&info);
+}
+
+int main(int argc, char *argv[])
+{
+	/* Tell stdout not to buffer its content */
+	setbuf(stdout, NULL);
+
+	execute_memory_conversion_test(VM_MEM_SRC_ANONYMOUS_AND_RESTRICTED_MEMFD);
+
+	/* Needs 2MB Hugepages */
+	if (get_free_huge_2mb_pages() >= 1) {
+		printf("Running private mem test with 2M pages\n");
+		execute_memory_conversion_test(VM_MEM_SRC_ANON_HTLB2M_AND_RESTRICTED_MEMFD);
+	} else
+		printf("Skipping private mem test with 2M pages\n");
+
+	return 0;
+}
-- 
2.38.1.431.g37b22c650d-goog