Message-Id: <20220511000811.384766-3-vannapurve@google.com>
Date:   Wed, 11 May 2022 00:08:04 +0000
From:   Vishal Annapurve <vannapurve@...gle.com>
To:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Cc:     pbonzini@...hat.com, vkuznets@...hat.com, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        hpa@...or.com, shauh@...nel.org, yang.zhong@...el.com,
        drjones@...hat.com, ricarkol@...gle.com, aaronlewis@...gle.com,
        wei.w.wang@...el.com, kirill.shutemov@...ux.intel.com,
        corbet@....net, hughd@...gle.com, jlayton@...nel.org,
        bfields@...ldses.org, akpm@...ux-foundation.org,
        chao.p.peng@...ux.intel.com, yu.c.zhang@...ux.intel.com,
        jun.nakajima@...el.com, dave.hansen@...el.com,
        michael.roth@....com, qperret@...gle.com, steven.price@....com,
        ak@...ux.intel.com, david@...hat.com, luto@...nel.org,
        vbabka@...e.cz, marcorr@...gle.com, erdemaktas@...gle.com,
        pgonda@...gle.com, nikunj@....com, seanjc@...gle.com,
        diviness@...gle.com, Vishal Annapurve <vannapurve@...gle.com>
Subject: [RFC V2 PATCH 2/8] selftests: kvm: Add a basic selftest to test
 private memory

Add KVM selftest to access private memory privately
from the guest to test that memory updates from guest
and userspace vmm don't affect each other.

Signed-off-by: Vishal Annapurve <vannapurve@...gle.com>
---
 tools/testing/selftests/kvm/Makefile          |   1 +
 tools/testing/selftests/kvm/priv_memfd_test.c | 283 ++++++++++++++++++
 2 files changed, 284 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/priv_memfd_test.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 21c2dbd21a81..f2f9a8546c66 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -97,6 +97,7 @@ TEST_GEN_PROGS_x86_64 += max_guest_memory_test
 TEST_GEN_PROGS_x86_64 += memslot_modification_stress_test
 TEST_GEN_PROGS_x86_64 += memslot_perf_test
 TEST_GEN_PROGS_x86_64 += rseq_test
+TEST_GEN_PROGS_x86_64 += priv_memfd_test
 TEST_GEN_PROGS_x86_64 += set_memory_region_test
 TEST_GEN_PROGS_x86_64 += steal_time
 TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test
diff --git a/tools/testing/selftests/kvm/priv_memfd_test.c b/tools/testing/selftests/kvm/priv_memfd_test.c
new file mode 100644
index 000000000000..bbb58c62e186
--- /dev/null
+++ b/tools/testing/selftests/kvm/priv_memfd_test.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.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 <processor.h>
+
+#define TEST_MEM_GPA		0xb0000000
+#define TEST_MEM_SIZE		0x2000
+#define TEST_MEM_END		(TEST_MEM_GPA + TEST_MEM_SIZE)
+#define TEST_MEM_DATA_PAT1	0x6666666666666666
+#define TEST_MEM_DATA_PAT2	0x9999999999999999
+#define TEST_MEM_DATA_PAT3	0x3333333333333333
+#define TEST_MEM_DATA_PAT4	0xaaaaaaaaaaaaaaaa
+
+enum mem_op {
+	SET_PAT,
+	VERIFY_PAT
+};
+
+#define TEST_MEM_SLOT		10
+
+#define VCPU_ID			0
+
+#define VM_STAGE_PROCESSED(x)	pr_info("Processed stage %s\n", #x)
+
+typedef bool (*vm_stage_handler_fn)(struct kvm_vm *,
+				void *, uint64_t);
+typedef void (*guest_code_fn)(void);
+struct test_run_helper {
+	char *test_desc;
+	vm_stage_handler_fn vmst_handler;
+	guest_code_fn guest_fn;
+	void *shared_mem;
+	int priv_memfd;
+};
+
+/* Guest code in selftests is loaded to guest memory using kvm_vm_elf_load
+ * which doesn't handle global offset table updates. Calling standard libc
+ * functions would normally result in referring to the global offset table.
+ * Adding O1 here seems to prohibit compiler from replacing the memory
+ * operations with standard libc functions such as memset.
+ */
+static bool __attribute__((optimize("O1"))) do_mem_op(enum mem_op op,
+		void *mem, uint64_t pat, uint32_t size)
+{
+	uint64_t *buf = (uint64_t *)mem;
+	uint32_t chunk_size = sizeof(pat);
+	uint64_t mem_addr = (uint64_t)mem;
+
+	if (((mem_addr % chunk_size) != 0) || ((size % chunk_size) != 0))
+		return false;
+
+	for (uint32_t i = 0; i < (size / chunk_size); i++) {
+		if (op == SET_PAT)
+			buf[i] = pat;
+		if (op == VERIFY_PAT) {
+			if (buf[i] != pat)
+				return false;
+		}
+	}
+
+	return true;
+}
+
+/* Test to verify guest private accesses on private memory with following steps:
+ * 1) Upon entry, guest signals VMM that it has started.
+ * 2) VMM populates the shared memory with known pattern and continues guest
+ *    execution.
+ * 3) Guest writes a different pattern on the private memory and signals VMM
+ *      that it has updated private memory.
+ * 4) VMM verifies its shared memory contents to be same as the data populated
+ *      in step 2 and continues guest execution.
+ * 5) Guest verifies its private memory contents to be same as the data
+ *      populated in step 3 and marks the end of the guest execution.
+ */
+#define PMPAT_ID				0
+#define PMPAT_DESC				"PrivateMemoryPrivateAccessTest"
+
+/* Guest code execution stages for private mem access test */
+#define PMPAT_GUEST_STARTED			0ULL
+#define PMPAT_GUEST_PRIV_MEM_UPDATED		1ULL
+
+static bool pmpat_handle_vm_stage(struct kvm_vm *vm,
+			void *test_info,
+			uint64_t stage)
+{
+	void *shared_mem = ((struct test_run_helper *)test_info)->shared_mem;
+
+	switch (stage) {
+	case PMPAT_GUEST_STARTED: {
+		/* Initialize the contents of shared memory */
+		TEST_ASSERT(do_mem_op(SET_PAT, shared_mem,
+			TEST_MEM_DATA_PAT1, TEST_MEM_SIZE),
+			"Shared memory update failure");
+		VM_STAGE_PROCESSED(PMPAT_GUEST_STARTED);
+		break;
+	}
+	case PMPAT_GUEST_PRIV_MEM_UPDATED: {
+		/* verify host updated data is still intact */
+		TEST_ASSERT(do_mem_op(VERIFY_PAT, shared_mem,
+			TEST_MEM_DATA_PAT1, TEST_MEM_SIZE),
+			"Shared memory view mismatch");
+		VM_STAGE_PROCESSED(PMPAT_GUEST_PRIV_MEM_UPDATED);
+		break;
+	}
+	default:
+		printf("Unhandled VM stage %ld\n", stage);
+		return false;
+	}
+
+	return true;
+}
+
+static void pmpat_guest_code(void)
+{
+	void *priv_mem = (void *)TEST_MEM_GPA;
+	int ret;
+
+	GUEST_SYNC(PMPAT_GUEST_STARTED);
+
+	/* Mark the GPA range to be treated as always accessed privately */
+	ret = kvm_hypercall(KVM_HC_MAP_GPA_RANGE, TEST_MEM_GPA,
+		TEST_MEM_SIZE >> MIN_PAGE_SHIFT,
+		KVM_MARK_GPA_RANGE_ENC_ACCESS, 0);
+	GUEST_ASSERT_1(ret == 0, ret);
+
+	GUEST_ASSERT(do_mem_op(SET_PAT, priv_mem, TEST_MEM_DATA_PAT2,
+			TEST_MEM_SIZE));
+	GUEST_SYNC(PMPAT_GUEST_PRIV_MEM_UPDATED);
+
+	GUEST_ASSERT(do_mem_op(VERIFY_PAT, priv_mem,
+			TEST_MEM_DATA_PAT2, TEST_MEM_SIZE));
+
+	GUEST_DONE();
+}
+
+static struct test_run_helper priv_memfd_testsuite[] = {
+	[PMPAT_ID] = {
+		.test_desc = PMPAT_DESC,
+		.vmst_handler = pmpat_handle_vm_stage,
+		.guest_fn = pmpat_guest_code,
+	},
+};
+
+static void vcpu_work(struct kvm_vm *vm, uint32_t test_id)
+{
+	struct kvm_run *run;
+	struct ucall uc;
+	uint64_t cmd;
+
+	/*
+	 * Loop until the guest is done.
+	 */
+	run = vcpu_state(vm, VCPU_ID);
+
+	while (true) {
+		vcpu_run(vm, VCPU_ID);
+
+		if (run->exit_reason == KVM_EXIT_IO) {
+			cmd = get_ucall(vm, VCPU_ID, &uc);
+			if (cmd != UCALL_SYNC)
+				break;
+
+			if (!priv_memfd_testsuite[test_id].vmst_handler(
+				vm, &priv_memfd_testsuite[test_id], uc.args[1]))
+				break;
+
+			continue;
+		}
+
+		TEST_FAIL("Unhandled VCPU exit reason %d\n", run->exit_reason);
+		break;
+	}
+
+	if (run->exit_reason == KVM_EXIT_IO && cmd == UCALL_ABORT)
+		TEST_FAIL("%s at %s:%ld, val = %lu", (const char *)uc.args[0],
+			  __FILE__, uc.args[1], uc.args[2]);
+}
+
+static void priv_memory_region_add(struct kvm_vm *vm, void *mem, uint32_t slot,
+				uint32_t size, uint64_t guest_addr,
+				uint32_t priv_fd, uint64_t priv_offset)
+{
+	struct kvm_userspace_memory_region_ext region_ext;
+	int ret;
+
+	region_ext.region.slot = slot;
+	region_ext.region.flags = KVM_MEM_PRIVATE;
+	region_ext.region.guest_phys_addr = guest_addr;
+	region_ext.region.memory_size = size;
+	region_ext.region.userspace_addr = (uintptr_t) mem;
+	region_ext.private_fd = priv_fd;
+	region_ext.private_offset = priv_offset;
+	ret = ioctl(vm_get_fd(vm), KVM_SET_USER_MEMORY_REGION, &region_ext);
+	TEST_ASSERT(ret == 0, "Failed to register user region for gpa 0x%lx\n",
+		guest_addr);
+}
+
+/* Do private access to the guest's private memory */
+static void setup_and_execute_test(uint32_t test_id)
+{
+	struct kvm_vm *vm;
+	int priv_memfd;
+	int ret;
+	void *shared_mem;
+	struct kvm_enable_cap cap;
+
+	vm = vm_create_default(VCPU_ID, 0,
+				priv_memfd_testsuite[test_id].guest_fn);
+
+	/* Allocate shared memory */
+	shared_mem = mmap(NULL, TEST_MEM_SIZE,
+			PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0);
+	TEST_ASSERT(shared_mem != MAP_FAILED, "Failed to mmap() host");
+
+	/* Allocate private memory */
+	priv_memfd = memfd_create("vm_private_mem", MFD_INACCESSIBLE);
+	TEST_ASSERT(priv_memfd != -1, "Failed to create priv_memfd");
+	ret = fallocate(priv_memfd, 0, 0, TEST_MEM_SIZE);
+	TEST_ASSERT(ret != -1, "fallocate failed");
+
+	priv_memory_region_add(vm, shared_mem,
+				TEST_MEM_SLOT, TEST_MEM_SIZE,
+				TEST_MEM_GPA, priv_memfd, 0);
+
+	pr_info("Mapping test memory pages 0x%x page_size 0x%x\n",
+					TEST_MEM_SIZE/vm_get_page_size(vm),
+					vm_get_page_size(vm));
+	virt_map(vm, TEST_MEM_GPA, TEST_MEM_GPA,
+					(TEST_MEM_SIZE/vm_get_page_size(vm)));
+
+	/* Enable exit on KVM_HC_MAP_GPA_RANGE */
+	pr_info("Enabling exit on map_gpa_range hypercall\n");
+	ret = ioctl(vm_get_fd(vm), KVM_CHECK_EXTENSION, KVM_CAP_EXIT_HYPERCALL);
+	TEST_ASSERT(ret & (1 << KVM_HC_MAP_GPA_RANGE),
+				"VM exit on MAP_GPA_RANGE HC not supported");
+	cap.cap = KVM_CAP_EXIT_HYPERCALL;
+	cap.flags = 0;
+	cap.args[0] = (1 << KVM_HC_MAP_GPA_RANGE);
+	ret = ioctl(vm_get_fd(vm), KVM_ENABLE_CAP, &cap);
+	TEST_ASSERT(ret == 0,
+		"Failed to enable exit on MAP_GPA_RANGE hypercall\n");
+
+	priv_memfd_testsuite[test_id].shared_mem = shared_mem;
+	priv_memfd_testsuite[test_id].priv_memfd = priv_memfd;
+	vcpu_work(vm, test_id);
+
+	munmap(shared_mem, TEST_MEM_SIZE);
+	priv_memfd_testsuite[test_id].shared_mem = NULL;
+	close(priv_memfd);
+	priv_memfd_testsuite[test_id].priv_memfd = -1;
+	kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+	/* Tell stdout not to buffer its content */
+	setbuf(stdout, NULL);
+
+	for (uint32_t i = 0; i < ARRAY_SIZE(priv_memfd_testsuite); i++) {
+		pr_info("=== Starting test %s... ===\n",
+				priv_memfd_testsuite[i].test_desc);
+		setup_and_execute_test(i);
+		pr_info("--- completed test %s ---\n\n",
+				priv_memfd_testsuite[i].test_desc);
+	}
+
+	return 0;
+}
-- 
2.36.0.550.gb090851708-goog

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