As of today, trying to enable dirty-ring with a size bigger than the maximum will return an "argument list too long" error.
Change vm_enable_dirty_ring() to get the maximum size, then compare it to the desired size before enabling. If the value is invalid, print a more precise error message. Signed-off-by: Leonardo Bras <[email protected]> --- tools/testing/selftests/kvm/lib/kvm_util.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index 195f3fdae1e3..237f0ce0ae60 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -160,24 +160,34 @@ unsigned int kvm_check_cap(long cap) ret = __kvm_ioctl(kvm_fd, KVM_CHECK_EXTENSION, (void *)cap); TEST_ASSERT(ret >= 0, KVM_IOCTL_ERROR(KVM_CHECK_EXTENSION, ret)); kvm_free_fd(kvm_fd); return (unsigned int)ret; } void vm_enable_dirty_ring(struct kvm_vm *vm, u32 ring_size) { - if (vm_check_cap(vm, KVM_CAP_DIRTY_LOG_RING_ACQ_REL)) - vm_enable_cap(vm, KVM_CAP_DIRTY_LOG_RING_ACQ_REL, ring_size); - else - vm_enable_cap(vm, KVM_CAP_DIRTY_LOG_RING, ring_size); + long cap = KVM_CAP_DIRTY_LOG_RING_ACQ_REL; + int max_size = vm_check_cap(vm, cap); + + if (!max_size) { + cap = KVM_CAP_DIRTY_LOG_RING; + max_size = vm_check_cap(vm, cap); + } + + TEST_ASSERT(ring_size <= max_size && is_power_of_2(ring_size), + "Invalid dirty-ring size: Should be a power of two " + "smaller than %d entries\n", + max_size / sizeof(struct kvm_dirty_gfn)); + + vm_enable_cap(vm, cap, ring_size); vm->dirty_ring_size = ring_size; } static void vm_open(struct kvm_vm *vm) { vm->kvm_fd = _open_kvm_dev_path_or_exit(O_RDWR); TEST_REQUIRE(kvm_has_cap(KVM_CAP_IMMEDIATE_EXIT)); vm->fd = __kvm_ioctl(vm->kvm_fd, KVM_CREATE_VM, (void *)vm->type); -- 2.54.0
