// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2022, Google LLC.
*/
#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;
}
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