diff options
Diffstat (limited to 'tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c')
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c b/tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c new file mode 100644 index 000000000000..e0f642d2a3c4 --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c @@ -0,0 +1,484 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2022, Google LLC. + */ +#define _GNU_SOURCE /* for program_invocation_short_name */ +#include <fcntl.h> +#include <limits.h> +#include <pthread.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 <linux/sizes.h> + +#include <test_util.h> +#include <kvm_util.h> +#include <processor.h> + +#define BASE_DATA_SLOT 10 +#define BASE_DATA_GPA ((uint64_t)(1ull << 32)) +#define PER_CPU_DATA_SIZE ((uint64_t)(SZ_2M + PAGE_SIZE)) + +/* Horrific macro so that the line info is captured accurately :-( */ +#define memcmp_g(gpa, pattern, size) \ +do { \ + uint8_t *mem = (uint8_t *)gpa; \ + size_t i; \ + \ + for (i = 0; i < size; i++) \ + __GUEST_ASSERT(mem[i] == pattern, \ + "Guest expected 0x%x at offset %lu (gpa 0x%lx), got 0x%x", \ + pattern, i, gpa + i, mem[i]); \ +} while (0) + +static void memcmp_h(uint8_t *mem, uint64_t gpa, uint8_t pattern, size_t size) +{ + size_t i; + + for (i = 0; i < size; i++) + TEST_ASSERT(mem[i] == pattern, + "Host expected 0x%x at gpa 0x%lx, got 0x%x", + pattern, gpa + i, mem[i]); +} + +/* + * 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. + */ + +#define GUEST_STAGE(o, s) { .offset = o, .size = s } + +enum ucall_syncs { + SYNC_SHARED, + SYNC_PRIVATE, +}; + +static void guest_sync_shared(uint64_t gpa, uint64_t size, + uint8_t current_pattern, uint8_t new_pattern) +{ + GUEST_SYNC5(SYNC_SHARED, gpa, size, current_pattern, new_pattern); +} + +static void guest_sync_private(uint64_t gpa, uint64_t size, uint8_t pattern) +{ + GUEST_SYNC4(SYNC_PRIVATE, gpa, size, pattern); +} + +/* Arbitrary values, KVM doesn't care about the attribute flags. */ +#define MAP_GPA_SET_ATTRIBUTES BIT(0) +#define MAP_GPA_SHARED BIT(1) +#define MAP_GPA_DO_FALLOCATE BIT(2) + +static void guest_map_mem(uint64_t gpa, uint64_t size, bool map_shared, + bool do_fallocate) +{ + uint64_t flags = MAP_GPA_SET_ATTRIBUTES; + + if (map_shared) + flags |= MAP_GPA_SHARED; + if (do_fallocate) + flags |= MAP_GPA_DO_FALLOCATE; + kvm_hypercall_map_gpa_range(gpa, size, flags); +} + +static void guest_map_shared(uint64_t gpa, uint64_t size, bool do_fallocate) +{ + guest_map_mem(gpa, size, true, do_fallocate); +} + +static void guest_map_private(uint64_t gpa, uint64_t size, bool do_fallocate) +{ + guest_map_mem(gpa, size, false, do_fallocate); +} + +struct { + uint64_t offset; + uint64_t size; +} static const test_ranges[] = { + GUEST_STAGE(0, PAGE_SIZE), + GUEST_STAGE(0, SZ_2M), + GUEST_STAGE(PAGE_SIZE, PAGE_SIZE), + GUEST_STAGE(PAGE_SIZE, SZ_2M), + GUEST_STAGE(SZ_2M, PAGE_SIZE), +}; + +static void guest_test_explicit_conversion(uint64_t base_gpa, bool do_fallocate) +{ + const uint8_t def_p = 0xaa; + const uint8_t init_p = 0xcc; + uint64_t j; + int i; + + /* Memory should be shared by default. */ + memset((void *)base_gpa, def_p, PER_CPU_DATA_SIZE); + memcmp_g(base_gpa, def_p, PER_CPU_DATA_SIZE); + guest_sync_shared(base_gpa, PER_CPU_DATA_SIZE, def_p, init_p); + + memcmp_g(base_gpa, init_p, PER_CPU_DATA_SIZE); + + for (i = 0; i < ARRAY_SIZE(test_ranges); i++) { + uint64_t gpa = base_gpa + test_ranges[i].offset; + uint64_t size = test_ranges[i].size; + uint8_t p1 = 0x11; + uint8_t p2 = 0x22; + uint8_t p3 = 0x33; + uint8_t p4 = 0x44; + + /* + * Set the test region to pattern one to differentiate it from + * the data range as a whole (contains the initial pattern). + */ + memset((void *)gpa, p1, size); + + /* + * Convert to private, set and verify the private data, and + * then verify that the rest of the data (map shared) still + * holds the initial pattern, and that the host always sees the + * shared memory (initial pattern). Unlike shared memory, + * punching a hole in private memory is destructive, i.e. + * previous values aren't guaranteed to be preserved. + */ + guest_map_private(gpa, size, do_fallocate); + + if (size > PAGE_SIZE) { + memset((void *)gpa, p2, PAGE_SIZE); + goto skip; + } + + memset((void *)gpa, p2, size); + guest_sync_private(gpa, size, p1); + + /* + * Verify that the private memory was set to pattern two, and + * that shared memory still holds the initial pattern. + */ + memcmp_g(gpa, p2, size); + if (gpa > base_gpa) + memcmp_g(base_gpa, init_p, gpa - base_gpa); + if (gpa + size < base_gpa + PER_CPU_DATA_SIZE) + memcmp_g(gpa + size, init_p, + (base_gpa + PER_CPU_DATA_SIZE) - (gpa + size)); + + /* + * Convert odd-number page frames back to shared to verify KVM + * also correctly handles holes in private ranges. + */ + for (j = 0; j < size; j += PAGE_SIZE) { + if ((j >> PAGE_SHIFT) & 1) { + guest_map_shared(gpa + j, PAGE_SIZE, do_fallocate); + guest_sync_shared(gpa + j, PAGE_SIZE, p1, p3); + + memcmp_g(gpa + j, p3, PAGE_SIZE); + } else { + guest_sync_private(gpa + j, PAGE_SIZE, p1); + } + } + +skip: + /* + * Convert the entire region back to shared, explicitly write + * pattern three to fill in the even-number frames before + * asking the host to verify (and write pattern four). + */ + guest_map_shared(gpa, size, do_fallocate); + memset((void *)gpa, p3, size); + guest_sync_shared(gpa, size, p3, p4); + memcmp_g(gpa, p4, size); + + /* Reset the shared memory back to the initial pattern. */ + memset((void *)gpa, init_p, size); + + /* + * Free (via PUNCH_HOLE) *all* private memory so that the next + * iteration starts from a clean slate, e.g. with respect to + * whether or not there are pages/folios in guest_mem. + */ + guest_map_shared(base_gpa, PER_CPU_DATA_SIZE, true); + } +} + +static void guest_punch_hole(uint64_t gpa, uint64_t size) +{ + /* "Mapping" memory shared via fallocate() is done via PUNCH_HOLE. */ + uint64_t flags = MAP_GPA_SHARED | MAP_GPA_DO_FALLOCATE; + + kvm_hypercall_map_gpa_range(gpa, size, flags); +} + +/* + * Test that PUNCH_HOLE actually frees memory by punching holes without doing a + * proper conversion. Freeing (PUNCH_HOLE) should zap SPTEs, and reallocating + * (subsequent fault) should zero memory. + */ +static void guest_test_punch_hole(uint64_t base_gpa, bool precise) +{ + const uint8_t init_p = 0xcc; + int i; + + /* + * Convert the entire range to private, this testcase is all about + * punching holes in guest_memfd, i.e. shared mappings aren't needed. + */ + guest_map_private(base_gpa, PER_CPU_DATA_SIZE, false); + + for (i = 0; i < ARRAY_SIZE(test_ranges); i++) { + uint64_t gpa = base_gpa + test_ranges[i].offset; + uint64_t size = test_ranges[i].size; + + /* + * Free all memory before each iteration, even for the !precise + * case where the memory will be faulted back in. Freeing and + * reallocating should obviously work, and freeing all memory + * minimizes the probability of cross-testcase influence. + */ + guest_punch_hole(base_gpa, PER_CPU_DATA_SIZE); + + /* Fault-in and initialize memory, and verify the pattern. */ + if (precise) { + memset((void *)gpa, init_p, size); + memcmp_g(gpa, init_p, size); + } else { + memset((void *)base_gpa, init_p, PER_CPU_DATA_SIZE); + memcmp_g(base_gpa, init_p, PER_CPU_DATA_SIZE); + } + + /* + * Punch a hole at the target range and verify that reads from + * the guest succeed and return zeroes. + */ + guest_punch_hole(gpa, size); + memcmp_g(gpa, 0, size); + } +} + +static void guest_code(uint64_t base_gpa) +{ + /* + * Run the conversion test twice, with and without doing fallocate() on + * the guest_memfd backing when converting between shared and private. + */ + guest_test_explicit_conversion(base_gpa, false); + guest_test_explicit_conversion(base_gpa, true); + + /* + * Run the PUNCH_HOLE test twice too, once with the entire guest_memfd + * faulted in, once with only the target range faulted in. + */ + guest_test_punch_hole(base_gpa, false); + guest_test_punch_hole(base_gpa, true); + GUEST_DONE(); +} + +static void handle_exit_hypercall(struct kvm_vcpu *vcpu) +{ + struct kvm_run *run = vcpu->run; + uint64_t gpa = run->hypercall.args[0]; + uint64_t size = run->hypercall.args[1] * PAGE_SIZE; + bool set_attributes = run->hypercall.args[2] & MAP_GPA_SET_ATTRIBUTES; + bool map_shared = run->hypercall.args[2] & MAP_GPA_SHARED; + bool do_fallocate = run->hypercall.args[2] & MAP_GPA_DO_FALLOCATE; + struct kvm_vm *vm = vcpu->vm; + + TEST_ASSERT(run->hypercall.nr == KVM_HC_MAP_GPA_RANGE, + "Wanted MAP_GPA_RANGE (%u), got '%llu'", + KVM_HC_MAP_GPA_RANGE, run->hypercall.nr); + + if (do_fallocate) + vm_guest_mem_fallocate(vm, gpa, size, map_shared); + + if (set_attributes) + vm_set_memory_attributes(vm, gpa, size, + map_shared ? 0 : KVM_MEMORY_ATTRIBUTE_PRIVATE); + run->hypercall.ret = 0; +} + +static bool run_vcpus; + +static void *__test_mem_conversions(void *__vcpu) +{ + struct kvm_vcpu *vcpu = __vcpu; + struct kvm_run *run = vcpu->run; + struct kvm_vm *vm = vcpu->vm; + struct ucall uc; + + while (!READ_ONCE(run_vcpus)) + ; + + for ( ;; ) { + vcpu_run(vcpu); + + if (run->exit_reason == KVM_EXIT_HYPERCALL) { + handle_exit_hypercall(vcpu); + continue; + } + + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, + "Wanted KVM_EXIT_IO, got exit reason: %u (%s)", + run->exit_reason, exit_reason_str(run->exit_reason)); + + switch (get_ucall(vcpu, &uc)) { + case UCALL_ABORT: + REPORT_GUEST_ASSERT(uc); + case UCALL_SYNC: { + uint64_t gpa = uc.args[1]; + size_t size = uc.args[2]; + size_t i; + + TEST_ASSERT(uc.args[0] == SYNC_SHARED || + uc.args[0] == SYNC_PRIVATE, + "Unknown sync command '%ld'", uc.args[0]); + + for (i = 0; i < size; i += vm->page_size) { + size_t nr_bytes = min_t(size_t, vm->page_size, size - i); + uint8_t *hva = addr_gpa2hva(vm, gpa + i); + + /* In all cases, the host should observe the shared data. */ + memcmp_h(hva, gpa + i, uc.args[3], nr_bytes); + + /* For shared, write the new pattern to guest memory. */ + if (uc.args[0] == SYNC_SHARED) + memset(hva, uc.args[4], nr_bytes); + } + break; + } + case UCALL_DONE: + return NULL; + default: + TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd); + } + } +} + +static void test_mem_conversions(enum vm_mem_backing_src_type src_type, uint32_t nr_vcpus, + uint32_t nr_memslots) +{ + /* + * Allocate enough memory so that each vCPU's chunk of memory can be + * naturally aligned with respect to the size of the backing store. + */ + const size_t alignment = max_t(size_t, SZ_2M, get_backing_src_pagesz(src_type)); + const size_t per_cpu_size = align_up(PER_CPU_DATA_SIZE, alignment); + const size_t memfd_size = per_cpu_size * nr_vcpus; + const size_t slot_size = memfd_size / nr_memslots; + struct kvm_vcpu *vcpus[KVM_MAX_VCPUS]; + pthread_t threads[KVM_MAX_VCPUS]; + struct kvm_vm *vm; + int memfd, i, r; + + const struct vm_shape shape = { + .mode = VM_MODE_DEFAULT, + .type = KVM_X86_SW_PROTECTED_VM, + }; + + TEST_ASSERT(slot_size * nr_memslots == memfd_size, + "The memfd size (0x%lx) needs to be cleanly divisible by the number of memslots (%u)", + memfd_size, nr_memslots); + vm = __vm_create_with_vcpus(shape, nr_vcpus, 0, guest_code, vcpus); + + vm_enable_cap(vm, KVM_CAP_EXIT_HYPERCALL, (1 << KVM_HC_MAP_GPA_RANGE)); + + memfd = vm_create_guest_memfd(vm, memfd_size, 0); + + for (i = 0; i < nr_memslots; i++) + vm_mem_add(vm, src_type, BASE_DATA_GPA + slot_size * i, + BASE_DATA_SLOT + i, slot_size / vm->page_size, + KVM_MEM_GUEST_MEMFD, memfd, slot_size * i); + + for (i = 0; i < nr_vcpus; i++) { + uint64_t gpa = BASE_DATA_GPA + i * per_cpu_size; + + vcpu_args_set(vcpus[i], 1, gpa); + + /* + * Map only what is needed so that an out-of-bounds access + * results #PF => SHUTDOWN instead of data corruption. + */ + virt_map(vm, gpa, gpa, PER_CPU_DATA_SIZE / vm->page_size); + + pthread_create(&threads[i], NULL, __test_mem_conversions, vcpus[i]); + } + + WRITE_ONCE(run_vcpus, true); + + for (i = 0; i < nr_vcpus; i++) + pthread_join(threads[i], NULL); + + kvm_vm_free(vm); + + /* + * Allocate and free memory from the guest_memfd after closing the VM + * fd. The guest_memfd is gifted a reference to its owning VM, i.e. + * should prevent the VM from being fully destroyed until the last + * reference to the guest_memfd is also put. + */ + r = fallocate(memfd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, memfd_size); + TEST_ASSERT(!r, __KVM_SYSCALL_ERROR("fallocate()", r)); + + r = fallocate(memfd, FALLOC_FL_KEEP_SIZE, 0, memfd_size); + TEST_ASSERT(!r, __KVM_SYSCALL_ERROR("fallocate()", r)); + + close(memfd); +} + +static void usage(const char *cmd) +{ + puts(""); + printf("usage: %s [-h] [-m nr_memslots] [-s mem_type] [-n nr_vcpus]\n", cmd); + puts(""); + backing_src_help("-s"); + puts(""); + puts(" -n: specify the number of vcpus (default: 1)"); + puts(""); + puts(" -m: specify the number of memslots (default: 1)"); + puts(""); +} + +int main(int argc, char *argv[]) +{ + enum vm_mem_backing_src_type src_type = DEFAULT_VM_MEM_SRC; + uint32_t nr_memslots = 1; + uint32_t nr_vcpus = 1; + int opt; + + TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM)); + + while ((opt = getopt(argc, argv, "hm:s:n:")) != -1) { + switch (opt) { + case 's': + src_type = parse_backing_src_type(optarg); + break; + case 'n': + nr_vcpus = atoi_positive("nr_vcpus", optarg); + break; + case 'm': + nr_memslots = atoi_positive("nr_memslots", optarg); + break; + case 'h': + default: + usage(argv[0]); + exit(0); + } + } + + test_mem_conversions(src_type, nr_vcpus, nr_memslots); + + return 0; +} |