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 | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index 9ddc047d5c27..fbd0aaa679d6 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -168,24 +168,36 @@ 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_get_dirty_ring_cap(); + int max_size; + + TEST_ASSERT(cap, "Dirty-ring not supported, check CONFIG_HAVE_KVM_DIRTY_RING"); + + TEST_ASSERT(is_power_of_2(ring_size), + "Dirty-ring size '0x%x' must be a power-of-2", ring_size); + TEST_ASSERT(ring_size >= getpagesize(), + "Dirty-ring size '0x%x' must be at least one (host) page", ring_size); + + max_size = vm_check_cap(vm, cap); + TEST_ASSERT(ring_size <= max_size, + "Dirty-ring size '0x%x' is larger than KVM's limit of '0x%x'", + ring_size, max_size); + + 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); -- 2.55.0
