[PATCH 5/6] KVM: selftests: Enable pre_fault_memory_test for arm64

Jack Thomson
2025-09-11T13:49:53Z

Enable the pre_fault_memory_test to run on arm64 by making it work with
different guest page sizes and testing multiple guest configurations.

Update the test_assert to compare against the UCALL_EXIT_REASON, for
portability, as arm64 exits with KVM_EXIT_MMIO while x86 uses
KVM_EXIT_IO.

Signed-off-by: Jack Thomson <jackabt@amazon.com>
---
tools/testing/selftests/kvm/Makefile.kvm | 1 +
.../selftests/kvm/pre_fault_memory_test.c | 79 ++++++++++++++-----
2 files changed, 59 insertions(+), 21 deletions(-)

diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index 90f03f00cb04..4db1737fad04 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -180,6 +180,7 @@ TEST_GEN_PROGS_arm64 += memslot_perf_test
TEST_GEN_PROGS_arm64 += mmu_stress_test
TEST_GEN_PROGS_arm64 += rseq_test
TEST_GEN_PROGS_arm64 += steal_time
+TEST_GEN_PROGS_arm64 += pre_fault_memory_test

TEST_GEN_PROGS_s390 = $(TEST_GEN_PROGS_COMMON)
TEST_GEN_PROGS_s390 += s390/memop
diff --git a/tools/testing/selftests/kvm/pre_fault_memory_test.c b/tools/testing/selftests/kvm/pre_fault_memory_test.c
index 0350a8896a2f..ed9848a8af60 100644
--- a/tools/testing/selftests/kvm/pre_fault_memory_test.c
+++ b/tools/testing/selftests/kvm/pre_fault_memory_test.c
@@ -10,19 +10,29 @@
#include <test_util.h>
#include <kvm_util.h>
#include <processor.h>
+#include <guest_modes.h>

/* Arbitrarily chosen values */
-#define TEST_SIZE (SZ_2M + PAGE_SIZE)
-#define TEST_NPAGES (TEST_SIZE / PAGE_SIZE)
+#define TEST_BASE_SIZE SZ_2M
#define TEST_SLOT 10

+/* Storage of test info to share with guest code */
+struct test_config {
+ int page_size;
+ uint64_t test_size;
+ uint64_t test_num_pages;
+};
+
+struct test_config test_config;
+
static void guest_code(uint64_t base_gpa)
{
volatile uint64_t val __used;
+ struct test_config *config = &test_config;
int i;

- for (i = 0; i < TEST_NPAGES; i++) {
- uint64_t *src = (uint64_t *)(base_gpa + i * PAGE_SIZE);
+ for (i = 0; i < config->test_num_pages; i++) {
+ uint64_t *src = (uint64_t *)(base_gpa + i * config->page_size);

val = *src;
}
@@ -63,11 +73,17 @@ static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa, u64 size,
"KVM_PRE_FAULT_MEMORY", ret, vcpu->vm);
}

-static void __test_pre_fault_memory(unsigned long vm_type, bool private)
+struct test_params {
+ unsigned long vm_type;
+ bool private;
+};
+
+static void __test_pre_fault_memory(enum vm_guest_mode guest_mode, void *arg)
{
+ struct test_params *p = arg;
const struct vm_shape shape = {
- .mode = VM_MODE_DEFAULT,
- .type = vm_type,
+ .mode = guest_mode,
+ .type = p->vm_type,
};
struct kvm_vcpu *vcpu;
struct kvm_run *run;
@@ -78,10 +94,17 @@ static void __test_pre_fault_memory(unsigned long vm_type, bool private)
uint64_t guest_test_virt_mem;
uint64_t alignment, guest_page_size;

+ pr_info("Testing guest mode: %s\n", vm_guest_mode_string(guest_mode));
+
vm = vm_create_shape_with_one_vcpu(shape, &vcpu, guest_code);

- alignment = guest_page_size = vm_guest_mode_params[VM_MODE_DEFAULT].page_size;
- guest_test_phys_mem = (vm->max_gfn - TEST_NPAGES) * guest_page_size;
+ guest_page_size = vm_guest_mode_params[guest_mode].page_size;
+
+ test_config.page_size = guest_page_size;
+ test_config.test_size = TEST_BASE_SIZE + test_config.page_size;
+ test_config.test_num_pages = vm_calc_num_guest_pages(vm->mode, test_config.test_size);
+
+ guest_test_phys_mem = (vm->max_gfn - test_config.test_num_pages) * test_config.page_size;
#ifdef __s390x__
alignment = max(0x100000UL, guest_page_size);
#else
@@ -91,22 +114,31 @@ static void __test_pre_fault_memory(unsigned long vm_type, bool private)
guest_test_virt_mem = guest_test_phys_mem & ((1ULL << (vm->va_bits - 1)) - 1);

vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
- guest_test_phys_mem, TEST_SLOT, TEST_NPAGES,
- private ? KVM_MEM_GUEST_MEMFD : 0);
- virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, TEST_NPAGES);
-
- if (private)
- vm_mem_set_private(vm, guest_test_phys_mem, TEST_SIZE);
- pre_fault_memory(vcpu, guest_test_phys_mem, SZ_2M, 0);
- pre_fault_memory(vcpu, guest_test_phys_mem + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
- pre_fault_memory(vcpu, guest_test_phys_mem + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+ guest_test_phys_mem, TEST_SLOT, test_config.test_num_pages,
+ p->private ? KVM_MEM_GUEST_MEMFD : 0);
+ virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, test_config.test_num_pages);
+
+ if (p->private)
+ vm_mem_set_private(vm, guest_test_phys_mem, test_config.test_size);
+ pre_fault_memory(vcpu, guest_test_phys_mem, TEST_BASE_SIZE, 0);
+ /* Test pre-faulting over an already faulted range */
+ pre_fault_memory(vcpu, guest_test_phys_mem, TEST_BASE_SIZE, 0);
+ pre_fault_memory(vcpu, guest_test_phys_mem + TEST_BASE_SIZE,
+ test_config.page_size * 2, test_config.page_size);
+ pre_fault_memory(vcpu, guest_test_phys_mem + test_config.test_size,
+ test_config.page_size, test_config.page_size);

vcpu_args_set(vcpu, 1, guest_test_virt_mem);
+
+ /* Export the shared variables to the guest. */
+ sync_global_to_guest(vm, test_config);
+
vcpu_run(vcpu);

run = vcpu->run;
- TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
- "Wanted KVM_EXIT_IO, got exit reason: %u (%s)",
+ TEST_ASSERT(run->exit_reason == UCALL_EXIT_REASON,
+ "Wanted %s, got exit reason: %u (%s)",
+ exit_reason_str(UCALL_EXIT_REASON),
run->exit_reason, exit_reason_str(run->exit_reason));

switch (get_ucall(vcpu, &uc)) {
@@ -130,7 +162,12 @@ static void test_pre_fault_memory(unsigned long vm_type, bool private)
return;
}

- __test_pre_fault_memory(vm_type, private);
+ struct test_params p = {
+ .vm_type = vm_type,
+ .private = private,
+ };
+
+ for_each_guest_mode(__test_pre_fault_memory, &p);
}

int main(int argc, char *argv[])
--
2.43.0