On Tue, Apr 20, 2021 at 10:07:16AM +0200, Paolo Bonzini wrote:
> On 18/04/21 14:43, Peter Xu wrote:
> > ----8<-----
> > diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
> > index 25230e799bc4..d3050d1c2cd0 100644
> > --- a/tools/testing/selftests/kvm/dirty_log_test.c
> > +++ b/tools/testing/selftests/kvm/dirty_log_test.c
> > @@ -377,7 +377,7 @@ static void dirty_ring_after_vcpu_run(struct kvm_vm *vm, int ret, int err)
> > /* A ucall-sync or ring-full event is allowed */
> > if (get_ucall(vm, VCPU_ID, NULL) == UCALL_SYNC) {
> > /* We should allow this to continue */
> > - ;
> > + vcpu_handle_sync_stop();
> > } else if (run->exit_reason == KVM_EXIT_DIRTY_RING_FULL ||
> > (ret == -1 && err == EINTR)) {
> > /* Update the flag first before pause */
> > ----8<-----
> >
> > That's my intention when I introduce vcpu_handle_sync_stop(), but forgot to
> > add...
>
> And possibly even this (untested though):
>
> diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
> index ffa4e2791926..918954f01cef 100644
> --- a/tools/testing/selftests/kvm/dirty_log_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_test.c
> @@ -383,6 +383,7 @@ static void dirty_ring_after_vcpu_run(struct kvm_vm *vm, int ret, int err)
> /* Update the flag first before pause */
> WRITE_ONCE(dirty_ring_vcpu_ring_full,
> run->exit_reason == KVM_EXIT_DIRTY_RING_FULL);
> + atomic_set(&vcpu_sync_stop_requested, false);
> sem_post(&sem_vcpu_stop);
> pr_info("vcpu stops because %s...\n",
> dirty_ring_vcpu_ring_full ?
> @@ -804,8 +805,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
> * the flush of the last page, and since we handle the last
> * page specially verification will succeed anyway.
> */
> - assert(host_log_mode == LOG_MODE_DIRTY_RING ||
> - atomic_read(&vcpu_sync_stop_requested) == false);
> + assert(atomic_read(&vcpu_sync_stop_requested) == false);
> vm_dirty_log_verify(mode, bmap);
> sem_post(&sem_vcpu_cont);
>
> You can submit all these as a separate patch.
But it could race, then?
main thread vcpu thread
----------- -----------
ring full
vcpu_sync_stop_requested=0
sem_post(&sem_vcpu_stop)
vcpu_sync_stop_requested=1
sem_wait(&sem_vcpu_stop)
assert(vcpu_sync_stop_requested==0) <----
Thanks,
--
Peter Xu
