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@google.com --- tools/testing/selftests/kvm/Makefile | 1 + tools/testing/selftests/kvm/priv_memfd_test.c | 257 ++++++++++++++++++ 2 files changed, 258 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..11ccdb853a84 --- /dev/null +++ b/tools/testing/selftests/kvm/priv_memfd_test.c @@ -0,0 +1,257 @@ +// 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 SHARED_MEM_DATA_BYTE 0x66 +#define PRIV_MEM_DATA_BYTE 0x99 + +#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; +}; + +static bool verify_byte_pattern(void *mem, uint8_t byte, uint32_t size) +{ + uint8_t *buf = (uint8_t *)mem; + + for (uint32_t i = 0; i < size; i++) { + if (buf[i] != byte) + 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 */ + memset(shared_mem, SHARED_MEM_DATA_BYTE, TEST_MEM_SIZE); + VM_STAGE_PROCESSED(PMPAT_GUEST_STARTED); + break; + } + case PMPAT_GUEST_PRIV_MEM_UPDATED: { + /* verify host updated data is still intact */ + TEST_ASSERT(verify_byte_pattern(shared_mem, + SHARED_MEM_DATA_BYTE, 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); + + memset(priv_mem, PRIV_MEM_DATA_BYTE, TEST_MEM_SIZE); + GUEST_SYNC(PMPAT_GUEST_PRIV_MEM_UPDATED); + + GUEST_ASSERT(verify_byte_pattern(priv_mem, + PRIV_MEM_DATA_BYTE, 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, ®ion_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; +}