diff options
Diffstat (limited to 'tools/testing/selftests/kvm/pre_fault_memory_test.c')
| -rw-r--r-- | tools/testing/selftests/kvm/pre_fault_memory_test.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/pre_fault_memory_test.c b/tools/testing/selftests/kvm/pre_fault_memory_test.c new file mode 100644 index 000000000000..93e603d91311 --- /dev/null +++ b/tools/testing/selftests/kvm/pre_fault_memory_test.c @@ -0,0 +1,239 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2024, Intel, Inc + * + * Author: + * Isaku Yamahata <isaku.yamahata at gmail.com> + */ +#include <linux/sizes.h> + +#include <test_util.h> +#include <kvm_util.h> +#include <processor.h> +#include <pthread.h> + +/* Arbitrarily chosen values */ +#define TEST_SIZE (SZ_2M + PAGE_SIZE) +#define TEST_NPAGES (TEST_SIZE / PAGE_SIZE) +#define TEST_SLOT 10 + +static void guest_code(uint64_t base_gva) +{ + volatile uint64_t val __used; + int i; + + for (i = 0; i < TEST_NPAGES; i++) { + uint64_t *src = (uint64_t *)(base_gva + i * PAGE_SIZE); + + val = *src; + } + + GUEST_DONE(); +} + +struct slot_worker_data { + struct kvm_vm *vm; + u64 gpa; + uint32_t flags; + bool worker_ready; + bool prefault_ready; + bool recreate_slot; +}; + +static void *delete_slot_worker(void *__data) +{ + struct slot_worker_data *data = __data; + struct kvm_vm *vm = data->vm; + + WRITE_ONCE(data->worker_ready, true); + + while (!READ_ONCE(data->prefault_ready)) + cpu_relax(); + + vm_mem_region_delete(vm, TEST_SLOT); + + while (!READ_ONCE(data->recreate_slot)) + cpu_relax(); + + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, data->gpa, + TEST_SLOT, TEST_NPAGES, data->flags); + + return NULL; +} + +static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 base_gpa, u64 offset, + u64 size, u64 expected_left, bool private) +{ + struct kvm_pre_fault_memory range = { + .gpa = base_gpa + offset, + .size = size, + .flags = 0, + }; + struct slot_worker_data data = { + .vm = vcpu->vm, + .gpa = base_gpa, + .flags = private ? KVM_MEM_GUEST_MEMFD : 0, + }; + bool slot_recreated = false; + pthread_t slot_worker; + int ret, save_errno; + u64 prev; + + /* + * Concurrently delete (and recreate) the slot to test KVM's handling + * of a racing memslot deletion with prefaulting. + */ + pthread_create(&slot_worker, NULL, delete_slot_worker, &data); + + while (!READ_ONCE(data.worker_ready)) + cpu_relax(); + + WRITE_ONCE(data.prefault_ready, true); + + for (;;) { + prev = range.size; + ret = __vcpu_ioctl(vcpu, KVM_PRE_FAULT_MEMORY, &range); + save_errno = errno; + TEST_ASSERT((range.size < prev) ^ (ret < 0), + "%sexpecting range.size to change on %s", + ret < 0 ? "not " : "", + ret < 0 ? "failure" : "success"); + + /* + * Immediately retry prefaulting if KVM was interrupted by an + * unrelated signal/event. + */ + if (ret < 0 && save_errno == EINTR) + continue; + + /* + * Tell the worker to recreate the slot in order to complete + * prefaulting (if prefault didn't already succeed before the + * slot was deleted) and/or to prepare for the next testcase. + * Wait for the worker to exit so that the next invocation of + * prefaulting is guaranteed to complete (assuming no KVM bugs). + */ + if (!slot_recreated) { + WRITE_ONCE(data.recreate_slot, true); + pthread_join(slot_worker, NULL); + slot_recreated = true; + + /* + * Retry prefaulting to get a stable result, i.e. to + * avoid seeing random EAGAIN failures. Don't retry if + * prefaulting already succeeded, as KVM disallows + * prefaulting with size=0, i.e. blindly retrying would + * result in test failures due to EINVAL. KVM should + * always return success if all bytes are prefaulted, + * i.e. there is no need to guard against EAGAIN being + * returned. + */ + if (range.size) + continue; + } + + /* + * All done if there are no remaining bytes to prefault, or if + * prefaulting failed (EINTR was handled above, and EAGAIN due + * to prefaulting a memslot that's being actively deleted should + * be impossible since the memslot has already been recreated). + */ + if (!range.size || ret < 0) + break; + } + + TEST_ASSERT(range.size == expected_left, + "Completed with %llu bytes left, expected %lu", + range.size, expected_left); + + /* + * Assert success if prefaulting the entire range should succeed, i.e. + * complete with no bytes remaining. Otherwise prefaulting should have + * failed due to ENOENT (due to RET_PF_EMULATE for emulated MMIO when + * no memslot exists). + */ + if (!expected_left) + TEST_ASSERT_VM_VCPU_IOCTL(!ret, KVM_PRE_FAULT_MEMORY, ret, vcpu->vm); + else + TEST_ASSERT_VM_VCPU_IOCTL(ret && save_errno == ENOENT, + KVM_PRE_FAULT_MEMORY, ret, vcpu->vm); +} + +static void __test_pre_fault_memory(unsigned long vm_type, bool private) +{ + uint64_t gpa, gva, alignment, guest_page_size; + const struct vm_shape shape = { + .mode = VM_MODE_DEFAULT, + .type = vm_type, + }; + struct kvm_vcpu *vcpu; + struct kvm_run *run; + struct kvm_vm *vm; + struct ucall uc; + + vm = vm_create_shape_with_one_vcpu(shape, &vcpu, guest_code); + + alignment = guest_page_size = vm_guest_mode_params[VM_MODE_DEFAULT].page_size; + gpa = (vm->max_gfn - TEST_NPAGES) * guest_page_size; +#ifdef __s390x__ + alignment = max(0x100000UL, guest_page_size); +#else + alignment = SZ_2M; +#endif + gpa = align_down(gpa, alignment); + gva = gpa & ((1ULL << (vm->va_bits - 1)) - 1); + + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, gpa, TEST_SLOT, + TEST_NPAGES, private ? KVM_MEM_GUEST_MEMFD : 0); + virt_map(vm, gva, gpa, TEST_NPAGES); + + if (private) + vm_mem_set_private(vm, gpa, TEST_SIZE); + + pre_fault_memory(vcpu, gpa, 0, SZ_2M, 0, private); + pre_fault_memory(vcpu, gpa, SZ_2M, PAGE_SIZE * 2, PAGE_SIZE, private); + pre_fault_memory(vcpu, gpa, TEST_SIZE, PAGE_SIZE, PAGE_SIZE, private); + + vcpu_args_set(vcpu, 1, gva); + vcpu_run(vcpu); + + run = vcpu->run; + 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); + break; + case UCALL_DONE: + break; + default: + TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd); + break; + } + + kvm_vm_free(vm); +} + +static void test_pre_fault_memory(unsigned long vm_type, bool private) +{ + if (vm_type && !(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type))) { + pr_info("Skipping tests for vm_type 0x%lx\n", vm_type); + return; + } + + __test_pre_fault_memory(vm_type, private); +} + +int main(int argc, char *argv[]) +{ + TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY)); + + test_pre_fault_memory(0, false); +#ifdef __x86_64__ + test_pre_fault_memory(KVM_X86_SW_PROTECTED_VM, false); + test_pre_fault_memory(KVM_X86_SW_PROTECTED_VM, true); +#endif + return 0; +} |