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KVM: selftests: aarch64: Add userfaultfd tests into page_fault_test 

Add some userfaultfd tests into page_fault_test. Punch holes into the
data and/or page-table memslots, perform some accesses, and check that
the faults are taken (or not taken) when expected.

Signed-off-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221017195834.2295901-12-ricarkol@google.com
This commit is contained in:
Ricardo Koller 2022-10-17 19:58:31 +00:00 committed by Marc Zyngier
parent 35c5810157
commit 3b1d915659
1 changed files with 187 additions and 0 deletions
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187
tools/testing/selftests/kvm/aarch64/page_fault_test.c
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@ -35,6 +35,12 @@ static uint64_t *guest_test_memory = (uint64_t *)TEST_GVA;
#define PREPARE_FN_NR 10
#define CHECK_FN_NR 10
static struct event_cnt {
int uffd_faults;
/* uffd_faults is incremented from multiple threads. */
pthread_mutex_t uffd_faults_mutex;
} events;
struct test_desc {
const char *name;
uint64_t mem_mark_cmd;
@ -42,11 +48,14 @@ struct test_desc {
bool (*guest_prepare[PREPARE_FN_NR])(void);
void (*guest_test)(void);
void (*guest_test_check[CHECK_FN_NR])(void);
uffd_handler_t uffd_pt_handler;
uffd_handler_t uffd_data_handler;
void (*dabt_handler)(struct ex_regs *regs);
void (*iabt_handler)(struct ex_regs *regs);
uint32_t pt_memslot_flags;
uint32_t data_memslot_flags;
bool skip;
struct event_cnt expected_events;
};
struct test_params {
@ -263,7 +272,110 @@ static void no_iabt_handler(struct ex_regs *regs)
GUEST_ASSERT_1(false, regs->pc);
}
static struct uffd_args {
char *copy;
void *hva;
uint64_t paging_size;
} pt_args, data_args;
/* Returns true to continue the test, and false if it should be skipped. */
static int uffd_generic_handler(int uffd_mode, int uffd, struct uffd_msg *msg,
struct uffd_args *args, bool expect_write)
{
uint64_t addr = msg->arg.pagefault.address;
uint64_t flags = msg->arg.pagefault.flags;
struct uffdio_copy copy;
int ret;
TEST_ASSERT(uffd_mode == UFFDIO_REGISTER_MODE_MISSING,
"The only expected UFFD mode is MISSING");
ASSERT_EQ(!!(flags & UFFD_PAGEFAULT_FLAG_WRITE), expect_write);
ASSERT_EQ(addr, (uint64_t)args->hva);
pr_debug("uffd fault: addr=%p write=%d\n",
(void *)addr, !!(flags & UFFD_PAGEFAULT_FLAG_WRITE));
copy.src = (uint64_t)args->copy;
copy.dst = addr;
copy.len = args->paging_size;
copy.mode = 0;
ret = ioctl(uffd, UFFDIO_COPY, &copy);
if (ret == -1) {
pr_info("Failed UFFDIO_COPY in 0x%lx with errno: %d\n",
addr, errno);
return ret;
}
pthread_mutex_lock(&events.uffd_faults_mutex);
events.uffd_faults += 1;
pthread_mutex_unlock(&events.uffd_faults_mutex);
return 0;
}
static int uffd_pt_write_handler(int mode, int uffd, struct uffd_msg *msg)
{
return uffd_generic_handler(mode, uffd, msg, &pt_args, true);
}
static int uffd_data_write_handler(int mode, int uffd, struct uffd_msg *msg)
{
return uffd_generic_handler(mode, uffd, msg, &data_args, true);
}
static int uffd_data_read_handler(int mode, int uffd, struct uffd_msg *msg)
{
return uffd_generic_handler(mode, uffd, msg, &data_args, false);
}
static void setup_uffd_args(struct userspace_mem_region *region,
struct uffd_args *args)
{
args->hva = (void *)region->region.userspace_addr;
args->paging_size = region->region.memory_size;
args->copy = malloc(args->paging_size);
TEST_ASSERT(args->copy, "Failed to allocate data copy.");
memcpy(args->copy, args->hva, args->paging_size);
}
static void setup_uffd(struct kvm_vm *vm, struct test_params *p,
struct uffd_desc **pt_uffd, struct uffd_desc **data_uffd)
{
struct test_desc *test = p->test_desc;
int uffd_mode = UFFDIO_REGISTER_MODE_MISSING;
setup_uffd_args(vm_get_mem_region(vm, MEM_REGION_PT), &pt_args);
setup_uffd_args(vm_get_mem_region(vm, MEM_REGION_TEST_DATA), &data_args);
*pt_uffd = NULL;
if (test->uffd_pt_handler)
*pt_uffd = uffd_setup_demand_paging(uffd_mode, 0,
pt_args.hva,
pt_args.paging_size,
test->uffd_pt_handler);
*data_uffd = NULL;
if (test->uffd_data_handler)
*data_uffd = uffd_setup_demand_paging(uffd_mode, 0,
data_args.hva,
data_args.paging_size,
test->uffd_data_handler);
}
static void free_uffd(struct test_desc *test, struct uffd_desc *pt_uffd,
struct uffd_desc *data_uffd)
{
if (test->uffd_pt_handler)
uffd_stop_demand_paging(pt_uffd);
if (test->uffd_data_handler)
uffd_stop_demand_paging(data_uffd);
free(pt_args.copy);
free(data_args.copy);
}
/* Returns false if the test should be skipped. */
static bool punch_hole_in_backing_store(struct kvm_vm *vm,
struct userspace_mem_region *region)
{
@ -404,6 +516,11 @@ static void setup_memslots(struct kvm_vm *vm, struct test_params *p)
vm->memslots[MEM_REGION_TEST_DATA] = TEST_DATA_MEMSLOT;
}
static void check_event_counts(struct test_desc *test)
{
ASSERT_EQ(test->expected_events.uffd_faults, events.uffd_faults);
}
static void print_test_banner(enum vm_guest_mode mode, struct test_params *p)
{
struct test_desc *test = p->test_desc;
@ -414,6 +531,11 @@ static void print_test_banner(enum vm_guest_mode mode, struct test_params *p)
vm_mem_backing_src_alias(p->src_type)->name);
}
static void reset_event_counts(void)
{
memset(&events, 0, sizeof(events));
}
/*
* This function either succeeds, skips the test (after setting test->skip), or
* fails with a TEST_FAIL that aborts all tests.
@ -453,6 +575,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
struct test_desc *test = p->test_desc;
struct kvm_vm *vm;
struct kvm_vcpu *vcpu;
struct uffd_desc *pt_uffd, *data_uffd;
print_test_banner(mode, p);
@ -465,7 +588,16 @@ static void run_test(enum vm_guest_mode mode, void *arg)
ucall_init(vm, NULL);
reset_event_counts();
/*
* Set some code in the data memslot for the guest to execute (only
* applicable to the EXEC tests). This has to be done before
* setup_uffd() as that function copies the memslot data for the uffd
* handler.
*/
load_exec_code_for_test(vm);
setup_uffd(vm, p, &pt_uffd, &data_uffd);
setup_abort_handlers(vm, vcpu, test);
vcpu_args_set(vcpu, 1, test);
@ -473,6 +605,14 @@ static void run_test(enum vm_guest_mode mode, void *arg)
ucall_uninit(vm);
kvm_vm_free(vm);
free_uffd(test, pt_uffd, data_uffd);
/*
* Make sure we check the events after the uffd threads have exited,
* which means they updated their respective event counters.
*/
if (!test->skip)
check_event_counts(test);
}
static void help(char *name)
@ -488,6 +628,7 @@ static void help(char *name)
#define SNAME(s) #s
#define SCAT2(a, b) SNAME(a ## _ ## b)
#define SCAT3(a, b, c) SCAT2(a, SCAT2(b, c))
#define SCAT4(a, b, c, d) SCAT2(a, SCAT3(b, c, d))
#define _CHECK(_test) _CHECK_##_test
#define _PREPARE(_test) _PREPARE_##_test
@ -515,6 +656,21 @@ static void help(char *name)
.mem_mark_cmd = _mark_cmd, \
.guest_test = _access, \
.guest_test_check = { _CHECK(_with_af) }, \
.expected_events = { 0 }, \
}
#define TEST_UFFD(_access, _with_af, _mark_cmd, \
_uffd_data_handler, _uffd_pt_handler, _uffd_faults) \
{ \
.name = SCAT4(uffd, _access, _with_af, #_mark_cmd), \
.guest_prepare = { _PREPARE(_with_af), \
_PREPARE(_access) }, \
.guest_test = _access, \
.mem_mark_cmd = _mark_cmd, \
.guest_test_check = { _CHECK(_with_af) }, \
.uffd_data_handler = _uffd_data_handler, \
.uffd_pt_handler = _uffd_pt_handler, \
.expected_events = { .uffd_faults = _uffd_faults, }, \
}
static struct test_desc tests[] = {
@ -545,6 +701,37 @@ static struct test_desc tests[] = {
TEST_ACCESS(guest_at, no_af, CMD_HOLE_DATA),
TEST_ACCESS(guest_dc_zva, no_af, CMD_HOLE_DATA),
/*
* Punch holes in the data and PT backing stores and mark them for
* userfaultfd handling. This should result in 2 faults: the access
* on the data backing store, and its respective S1 page table walk
* (S1PTW).
*/
TEST_UFFD(guest_read64, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_read_handler, uffd_pt_write_handler, 2),
/* no_af should also lead to a PT write. */
TEST_UFFD(guest_read64, no_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_read_handler, uffd_pt_write_handler, 2),
/* Note how that cas invokes the read handler. */
TEST_UFFD(guest_cas, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_read_handler, uffd_pt_write_handler, 2),
/*
* Can't test guest_at with_af as it's IMPDEF whether the AF is set.
* The S1PTW fault should still be marked as a write.
*/
TEST_UFFD(guest_at, no_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_read_handler, uffd_pt_write_handler, 1),
TEST_UFFD(guest_ld_preidx, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_read_handler, uffd_pt_write_handler, 2),
TEST_UFFD(guest_write64, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_write_handler, uffd_pt_write_handler, 2),
TEST_UFFD(guest_dc_zva, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_write_handler, uffd_pt_write_handler, 2),
TEST_UFFD(guest_st_preidx, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_write_handler, uffd_pt_write_handler, 2),
TEST_UFFD(guest_exec, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
uffd_data_read_handler, uffd_pt_write_handler, 2),
{ 0 }
};