dispute-coordinator: disabling in participation (#2637)

Closes #2225.

- [x] tests
- [x] fix todos
- [x] fix duplicates
- [x] make the check part of `potential_spam` 
- [x] fix a bug with votes insertion
- [x] guide changes
- [x] docs

---------

Co-authored-by: Tsvetomir Dimitrov <tsvetomir@parity.io>

polkadot/node/core/backing/src/lib.rs

@@ -1030,9 +1030,10 @@ async fn construct_per_relay_parent_state<Context>(
 	// Once runtime ver `DISABLED_VALIDATORS_RUNTIME_REQUIREMENT` is released remove this call to
 	// `get_disabled_validators_with_fallback`, add `request_disabled_validators` call to the
 	// `try_join!` above and use `try_runtime_api!` to get `disabled_validators`
-	let disabled_validators = get_disabled_validators_with_fallback(ctx.sender(), parent)
-		.await
-		.map_err(Error::UtilError)?;
+	let disabled_validators =
+		get_disabled_validators_with_fallback(ctx.sender(), parent).await.map_err(|e| {
+			Error::UtilError(TryFrom::try_from(e).expect("the conversion is infallible; qed"))
+		})?;
 
 	let signing_context = SigningContext { parent_hash: parent, session_index };
 	let validator = match Validator::construct(

polkadot/node/core/dispute-coordinator/src/import.rs

@@ -52,6 +52,8 @@ pub struct CandidateEnvironment<'a> {
 	executor_params: &'a ExecutorParams,
 	/// Validator indices controlled by this node.
 	controlled_indices: HashSet<ValidatorIndex>,
+	/// Indices of disabled validators at the `relay_parent`.
+	disabled_indices: HashSet<ValidatorIndex>,
 }
 
 #[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
@@ -66,6 +68,16 @@ impl<'a> CandidateEnvironment<'a> {
 		session_index: SessionIndex,
 		relay_parent: Hash,
 	) -> Option<CandidateEnvironment<'a>> {
+		let disabled_indices = runtime_info
+			.get_disabled_validators(ctx.sender(), relay_parent)
+			.await
+			.unwrap_or_else(|err| {
+				gum::info!(target: LOG_TARGET, ?err, "Failed to get disabled validators");
+				Vec::new()
+			})
+			.into_iter()
+			.collect();
+
 		let (session, executor_params) = match runtime_info
 			.get_session_info_by_index(ctx.sender(), relay_parent, session_index)
 			.await
@@ -76,7 +88,7 @@ impl<'a> CandidateEnvironment<'a> {
 		};
 
 		let controlled_indices = find_controlled_validator_indices(keystore, &session.validators);
-		Some(Self { session_index, session, executor_params, controlled_indices })
+		Some(Self { session_index, session, executor_params, controlled_indices, disabled_indices })
 	}
 
 	/// Validators in the candidate's session.
@@ -103,6 +115,11 @@ impl<'a> CandidateEnvironment<'a> {
 	pub fn controlled_indices(&'a self) -> &'a HashSet<ValidatorIndex> {
 		&self.controlled_indices
 	}
+
+	/// Indices of disabled validators at the `relay_parent`.
+	pub fn disabled_indices(&'a self) -> &'a HashSet<ValidatorIndex> {
+		&self.disabled_indices
+	}
 }
 
 /// Whether or not we already issued some statement about a candidate.
@@ -344,6 +361,14 @@ impl CandidateVoteState<CandidateVotes> {
 		&self.votes.candidate_receipt
 	}
 
+	/// Returns true if all the invalid votes are from disabled validators.
+	pub fn invalid_votes_all_disabled(
+		&self,
+		mut is_disabled: impl FnMut(&ValidatorIndex) -> bool,
+	) -> bool {
+		self.votes.invalid.keys().all(|i| is_disabled(i))
+	}
+
 	/// Extract `CandidateVotes` for handling import of new statements.
 	fn into_old_state(self) -> (CandidateVotes, CandidateVoteState<()>) {
 		let CandidateVoteState { votes, own_vote, dispute_status, byzantine_threshold_against } =

polkadot/node/core/dispute-coordinator/src/initialized.rs

@@ -17,7 +17,7 @@
 //! Dispute coordinator subsystem in initialized state (after first active leaf is received).
 
 use std::{
-	collections::{BTreeMap, VecDeque},
+	collections::{BTreeMap, HashSet, VecDeque},
 	sync::Arc,
 };
 
@@ -47,6 +47,7 @@ use polkadot_primitives::{
 	DisputeStatementSet, Hash, ScrapedOnChainVotes, SessionIndex, ValidDisputeStatementKind,
 	ValidatorId, ValidatorIndex,
 };
+use schnellru::{LruMap, UnlimitedCompact};
 
 use crate::{
 	db,
@@ -92,6 +93,9 @@ pub struct InitialData {
 pub(crate) struct Initialized {
 	keystore: Arc<LocalKeystore>,
 	runtime_info: RuntimeInfo,
+	/// We have the onchain state of disabled validators as well as the offchain
+	/// state that is based on the lost disputes.
+	offchain_disabled_validators: OffchainDisabledValidators,
 	/// This is the highest `SessionIndex` seen via `ActiveLeavesUpdate`. It doesn't matter if it
 	/// was cached successfully or not. It is used to detect ancient disputes.
 	highest_session_seen: SessionIndex,
@@ -130,10 +134,12 @@ impl Initialized {
 
 		let (participation_sender, participation_receiver) = mpsc::channel(1);
 		let participation = Participation::new(participation_sender, metrics.clone());
+		let offchain_disabled_validators = OffchainDisabledValidators::default();
 
 		Self {
 			keystore,
 			runtime_info,
+			offchain_disabled_validators,
 			highest_session_seen,
 			gaps_in_cache,
 			spam_slots,
@@ -319,13 +325,16 @@ impl Initialized {
 					self.runtime_info.pin_block(session_idx, new_leaf.unpin_handle);
 					// Fetch the last `DISPUTE_WINDOW` number of sessions unless there are no gaps
 					// in cache and we are not missing too many `SessionInfo`s
-					let mut lower_bound = session_idx.saturating_sub(DISPUTE_WINDOW.get() - 1);
-					if !self.gaps_in_cache && self.highest_session_seen > lower_bound {
-						lower_bound = self.highest_session_seen + 1
-					}
+					let prune_up_to = session_idx.saturating_sub(DISPUTE_WINDOW.get() - 1);
+					let fetch_lower_bound =
+						if !self.gaps_in_cache && self.highest_session_seen > prune_up_to {
+							self.highest_session_seen + 1
+						} else {
+							prune_up_to
+						};
 
 					// There is a new session. Perform a dummy fetch to cache it.
-					for idx in lower_bound..=session_idx {
+					for idx in fetch_lower_bound..=session_idx {
 						if let Err(err) = self
 							.runtime_info
 							.get_session_info_by_index(ctx.sender(), new_leaf.hash, idx)
@@ -344,11 +353,9 @@ impl Initialized {
 
 					self.highest_session_seen = session_idx;
 
-					db::v1::note_earliest_session(
-						overlay_db,
-						session_idx.saturating_sub(DISPUTE_WINDOW.get() - 1),
-					)?;
-					self.spam_slots.prune_old(session_idx.saturating_sub(DISPUTE_WINDOW.get() - 1));
+					db::v1::note_earliest_session(overlay_db, prune_up_to)?;
+					self.spam_slots.prune_old(prune_up_to);
+					self.offchain_disabled_validators.prune_old(prune_up_to);
 				},
 				Ok(_) => { /* no new session => nothing to cache */ },
 				Err(err) => {
@@ -978,11 +985,13 @@ impl Initialized {
 			Some(env) => env,
 		};
 
+		let n_validators = env.validators().len();
+
 		gum::trace!(
 			target: LOG_TARGET,
 			?candidate_hash,
 			?session,
-			num_validators = ?env.session_info().validators.len(),
+			?n_validators,
 			"Number of validators"
 		);
 
@@ -1084,18 +1093,42 @@ impl Initialized {
 			target: LOG_TARGET,
 			?candidate_hash,
 			?session,
-			num_validators = ?env.session_info().validators.len(),
+			?n_validators,
 			"Import result ready"
 		);
+
 		let new_state = import_result.new_state();
 
+		let byzantine_threshold = polkadot_primitives::byzantine_threshold(n_validators);
+		// combine on-chain with off-chain disabled validators
+		// process disabled validators in the following order:
+		// - on-chain disabled validators
+		// - prioritized order of off-chain disabled validators
+		// deduplicate the list and take at most `byzantine_threshold` validators
+		let disabled_validators = {
+			let mut d: HashSet<ValidatorIndex> = HashSet::new();
+			for v in env
+				.disabled_indices()
+				.iter()
+				.cloned()
+				.chain(self.offchain_disabled_validators.iter(session))
+			{
+				if d.len() == byzantine_threshold {
+					break
+				}
+				d.insert(v);
+			}
+			d
+		};
+
 		let is_included = self.scraper.is_candidate_included(&candidate_hash);
 		let is_backed = self.scraper.is_candidate_backed(&candidate_hash);
 		let own_vote_missing = new_state.own_vote_missing();
 		let is_disputed = new_state.is_disputed();
 		let is_confirmed = new_state.is_confirmed();
-		let potential_spam = is_potential_spam(&self.scraper, &new_state, &candidate_hash);
-		// We participate only in disputes which are not potential spam.
+		let potential_spam = is_potential_spam(&self.scraper, &new_state, &candidate_hash, |v| {
+			disabled_validators.contains(v)
+		});
 		let allow_participation = !potential_spam;
 
 		gum::trace!(
@@ -1106,6 +1139,7 @@ impl Initialized {
 			?candidate_hash,
 			confirmed = ?new_state.is_confirmed(),
 			has_invalid_voters = ?!import_result.new_invalid_voters().is_empty(),
+			n_disabled_validators = ?disabled_validators.len(),
 			"Is spam?"
 		);
 
@@ -1337,6 +1371,10 @@ impl Initialized {
 					);
 				}
 			}
+			for validator_index in new_state.votes().invalid.keys() {
+				self.offchain_disabled_validators
+					.insert_against_valid(session, *validator_index);
+			}
 			self.metrics.on_concluded_valid();
 		}
 		if import_result.is_freshly_concluded_against() {
@@ -1356,6 +1394,14 @@ impl Initialized {
 					);
 				}
 			}
+			for (validator_index, (kind, _sig)) in new_state.votes().valid.raw() {
+				let is_backer = kind.is_backing();
+				self.offchain_disabled_validators.insert_for_invalid(
+					session,
+					*validator_index,
+					is_backer,
+				);
+			}
 			self.metrics.on_concluded_invalid();
 		}
 
@@ -1591,3 +1637,82 @@ fn determine_undisputed_chain(
 
 	Ok(last)
 }
+
+#[derive(Default)]
+struct OffchainDisabledValidators {
+	// Ideally, we want to use the top `byzantine_threshold` offenders here based on the amount of
+	// stake slashed. However, given that slashing might be applied with a delay, we want to have
+	// some list of offenders as soon as disputes conclude offchain. This list only approximates
+	// the top offenders and only accounts for lost disputes. But that should be good enough to
+	// prevent spam attacks.
+	per_session: BTreeMap<SessionIndex, LostSessionDisputes>,
+}
+
+struct LostSessionDisputes {
+	// We separate lost disputes to prioritize "for invalid" offenders. And among those, we
+	// prioritize backing votes the most. There's no need to limit the size of these sets, as they
+	// are already limited by the number of validators in the session. We use `LruMap` to ensure
+	// the iteration order prioritizes most recently disputes lost over older ones in case we reach
+	// the limit.
+	backers_for_invalid: LruMap<ValidatorIndex, (), UnlimitedCompact>,
+	for_invalid: LruMap<ValidatorIndex, (), UnlimitedCompact>,
+	against_valid: LruMap<ValidatorIndex, (), UnlimitedCompact>,
+}
+
+impl Default for LostSessionDisputes {
+	fn default() -> Self {
+		Self {
+			backers_for_invalid: LruMap::new(UnlimitedCompact),
+			for_invalid: LruMap::new(UnlimitedCompact),
+			against_valid: LruMap::new(UnlimitedCompact),
+		}
+	}
+}
+
+impl OffchainDisabledValidators {
+	fn prune_old(&mut self, up_to_excluding: SessionIndex) {
+		// split_off returns everything after the given key, including the key.
+		let mut relevant = self.per_session.split_off(&up_to_excluding);
+		std::mem::swap(&mut relevant, &mut self.per_session);
+	}
+
+	fn insert_for_invalid(
+		&mut self,
+		session_index: SessionIndex,
+		validator_index: ValidatorIndex,
+		is_backer: bool,
+	) {
+		let entry = self.per_session.entry(session_index).or_default();
+		if is_backer {
+			entry.backers_for_invalid.insert(validator_index, ());
+		} else {
+			entry.for_invalid.insert(validator_index, ());
+		}
+	}
+
+	fn insert_against_valid(
+		&mut self,
+		session_index: SessionIndex,
+		validator_index: ValidatorIndex,
+	) {
+		self.per_session
+			.entry(session_index)
+			.or_default()
+			.against_valid
+			.insert(validator_index, ());
+	}
+
+	/// Iterate over all validators that are offchain disabled.
+	/// The order of iteration prioritizes `for_invalid` offenders (and backers among those) over
+	/// `against_valid` offenders. And most recently lost disputes over older ones.
+	/// NOTE: the iterator might contain duplicates.
+	fn iter(&self, session_index: SessionIndex) -> impl Iterator<Item = ValidatorIndex> + '_ {
+		self.per_session.get(&session_index).into_iter().flat_map(|e| {
+			e.backers_for_invalid
+				.iter()
+				.chain(e.for_invalid.iter())
+				.chain(e.against_valid.iter())
+				.map(|(i, _)| *i)
+		})
+	}
+}

polkadot/node/core/dispute-coordinator/src/lib.rs

@@ -370,8 +370,10 @@ impl DisputeCoordinatorSubsystem {
 					},
 				};
 			let vote_state = CandidateVoteState::new(votes, &env, now);
-
-			let potential_spam = is_potential_spam(&scraper, &vote_state, candidate_hash);
+			let onchain_disabled = env.disabled_indices();
+			let potential_spam = is_potential_spam(&scraper, &vote_state, candidate_hash, |v| {
+				onchain_disabled.contains(v)
+			});
 			let is_included =
 				scraper.is_candidate_included(&vote_state.votes().candidate_receipt.hash());
 
@@ -462,17 +464,20 @@ async fn wait_for_first_leaf<Context>(ctx: &mut Context) -> Result<Option<Activa
 /// Check wheter a dispute for the given candidate could be spam.
 ///
 /// That is the candidate could be made up.
-pub fn is_potential_spam<V>(
+pub fn is_potential_spam(
 	scraper: &ChainScraper,
-	vote_state: &CandidateVoteState<V>,
+	vote_state: &CandidateVoteState<CandidateVotes>,
 	candidate_hash: &CandidateHash,
+	is_disabled: impl FnMut(&ValidatorIndex) -> bool,
 ) -> bool {
 	let is_disputed = vote_state.is_disputed();
 	let is_included = scraper.is_candidate_included(candidate_hash);
 	let is_backed = scraper.is_candidate_backed(candidate_hash);
 	let is_confirmed = vote_state.is_confirmed();
+	let all_invalid_votes_disabled = vote_state.invalid_votes_all_disabled(is_disabled);
+	let ignore_disabled = !is_confirmed && all_invalid_votes_disabled;
 
-	is_disputed && !is_included && !is_backed && !is_confirmed
+	(is_disputed && !is_included && !is_backed && !is_confirmed) || ignore_disabled
 }
 
 /// Tell dispute-distribution to send all our votes.

polkadot/node/core/dispute-coordinator/src/participation/tests.rs

@@ -372,7 +372,6 @@ fn cannot_participate_if_cannot_recover_validation_code() {
 		let mut participation = Participation::new(sender, Metrics::default());
 		activate_leaf(&mut ctx, &mut participation, 10).await.unwrap();
 		participate(&mut ctx, &mut participation).await.unwrap();
-
 		recover_available_data(&mut ctx_handle).await;
 
 		assert_matches!(

polkadot/node/core/dispute-coordinator/src/tests.rs

@@ -257,7 +257,7 @@ impl TestState {
 		session: SessionIndex,
 		block_number: BlockNumber,
 		candidate_events: Vec<CandidateEvent>,
-	) {
+	) -> Hash {
 		assert!(block_number > 0);
 
 		let block_header = Header {
@@ -282,6 +282,8 @@ impl TestState {
 
 		self.handle_sync_queries(virtual_overseer, block_hash, session, candidate_events)
 			.await;
+
+		block_hash
 	}
 
 	/// Returns any sent `DisputeMessage`s.
@@ -406,6 +408,19 @@ impl TestState {
 				)) => {
 					tx.send(Ok(Vec::new())).unwrap();
 				},
+				AllMessages::RuntimeApi(RuntimeApiMessage::Request(
+					_new_leaf,
+					RuntimeApiRequest::Version(tx),
+				)) => {
+					tx.send(Ok(RuntimeApiRequest::DISABLED_VALIDATORS_RUNTIME_REQUIREMENT))
+						.unwrap();
+				},
+				AllMessages::RuntimeApi(RuntimeApiMessage::Request(
+					_new_leaf,
+					RuntimeApiRequest::DisabledValidators(tx),
+				)) => {
+					tx.send(Ok(Vec::new())).unwrap();
+				},
 				AllMessages::ChainApi(ChainApiMessage::Ancestors { hash, k, response_channel }) => {
 					let target_header = self
 						.headers
@@ -628,15 +643,19 @@ async fn participation_with_distribution(
 }
 
 fn make_valid_candidate_receipt() -> CandidateReceipt {
-	let mut candidate_receipt = dummy_candidate_receipt_bad_sig(dummy_hash(), dummy_hash());
-	candidate_receipt.commitments_hash = CandidateCommitments::default().hash();
-	candidate_receipt
+	make_another_valid_candidate_receipt(dummy_hash())
 }
 
 fn make_invalid_candidate_receipt() -> CandidateReceipt {
 	dummy_candidate_receipt_bad_sig(Default::default(), Some(Default::default()))
 }
 
+fn make_another_valid_candidate_receipt(relay_parent: Hash) -> CandidateReceipt {
+	let mut candidate_receipt = dummy_candidate_receipt_bad_sig(relay_parent, dummy_hash());
+	candidate_receipt.commitments_hash = CandidateCommitments::default().hash();
+	candidate_receipt
+}
+
 // Generate a `CandidateBacked` event from a `CandidateReceipt`. The rest is dummy data.
 fn make_candidate_backed_event(candidate_receipt: CandidateReceipt) -> CandidateEvent {
 	CandidateEvent::CandidateBacked(
@@ -740,6 +759,7 @@ fn too_many_unconfirmed_statements_are_considered_spam() {
 				.await;
 			gum::trace!("After sending `ImportStatements`");
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash1, HashMap::new())
 				.await;
 
@@ -875,6 +895,7 @@ fn approval_vote_import_works() {
 			.into_iter()
 			.collect();
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash1, approval_votes)
 				.await;
 
@@ -982,6 +1003,7 @@ fn dispute_gets_confirmed_via_participation() {
 				})
 				.await;
 			gum::debug!("After First import!");
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash1, HashMap::new())
 				.await;
 
@@ -1131,6 +1153,7 @@ fn dispute_gets_confirmed_at_byzantine_threshold() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash1, HashMap::new())
 				.await;
 
@@ -1255,6 +1278,7 @@ fn backing_statements_import_works_and_no_spam() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			assert_matches!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
 
 			{
@@ -1387,6 +1411,7 @@ fn conflicting_votes_lead_to_dispute_participation() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -1506,6 +1531,7 @@ fn positive_votes_dont_trigger_participation() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 
 			{
 				let (tx, rx) = oneshot::channel();
@@ -1616,6 +1642,7 @@ fn wrong_validator_index_is_ignored() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 
 			{
 				let (tx, rx) = oneshot::channel();
@@ -1693,6 +1720,7 @@ fn finality_votes_ignore_disputed_candidates() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -1769,14 +1797,10 @@ fn supermajority_valid_dispute_may_be_finalized() {
 
 			let candidate_receipt = make_valid_candidate_receipt();
 			let candidate_hash = candidate_receipt.hash();
+			let candidate_events = vec![make_candidate_backed_event(candidate_receipt.clone())];
 
 			test_state
-				.activate_leaf_at_session(
-					&mut virtual_overseer,
-					session,
-					1,
-					vec![make_candidate_backed_event(candidate_receipt.clone())],
-				)
+				.activate_leaf_at_session(&mut virtual_overseer, session, 1, candidate_events)
 				.await;
 
 			let supermajority_threshold =
@@ -1805,6 +1829,7 @@ fn supermajority_valid_dispute_may_be_finalized() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -1942,6 +1967,7 @@ fn concluded_supermajority_for_non_active_after_time() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -2058,6 +2084,7 @@ fn concluded_supermajority_against_non_active_after_time() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 			assert_matches!(confirmation_rx.await.unwrap(),
@@ -2173,6 +2200,7 @@ fn resume_dispute_without_local_statement() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -2217,13 +2245,23 @@ fn resume_dispute_without_local_statement() {
 			let candidate_receipt = make_valid_candidate_receipt();
 			let candidate_hash = candidate_receipt.hash();
 
-			participation_with_distribution(
+			participation_full_happy_path(
 				&mut virtual_overseer,
-				&candidate_hash,
 				candidate_receipt.commitments_hash,
 			)
 			.await;
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
+
+			assert_matches!(
+				virtual_overseer.recv().await,
+				AllMessages::DisputeDistribution(
+					DisputeDistributionMessage::SendDispute(msg)
+				) => {
+					assert_eq!(msg.candidate_receipt().hash(), candidate_hash);
+				}
+			);
+
 			let mut statements = Vec::new();
 			// Getting votes for supermajority. Should already have two valid votes.
 			for i in vec![3, 4, 5, 6, 7] {
@@ -2328,6 +2366,7 @@ fn resume_dispute_with_local_statement() {
 				})
 				.await;
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -2425,6 +2464,7 @@ fn resume_dispute_without_local_statement_or_local_key() {
 						},
 					})
 					.await;
+				handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 				handle_approval_vote_request(
 					&mut virtual_overseer,
 					&candidate_hash,
@@ -2516,6 +2556,7 @@ fn issue_local_statement_does_cause_distribution_but_not_duplicate_participation
 				})
 				.await;
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
 
 			// Initiate dispute locally:
@@ -2555,6 +2596,651 @@ fn issue_local_statement_does_cause_distribution_but_not_duplicate_participation
 	});
 }
 
+#[test]
+fn participation_with_onchain_disabling_unconfirmed() {
+	test_harness(|mut test_state, mut virtual_overseer| {
+		Box::pin(async move {
+			let session = 1;
+
+			test_state.handle_resume_sync(&mut virtual_overseer, session).await;
+
+			let candidate_receipt = make_valid_candidate_receipt();
+			let candidate_hash = candidate_receipt.hash();
+			let events = vec![make_candidate_included_event(candidate_receipt.clone())];
+
+			test_state
+				.activate_leaf_at_session(&mut virtual_overseer, session, 1, events)
+				.await;
+
+			let backer_index = ValidatorIndex(1);
+			let disabled_index = ValidatorIndex(2);
+
+			let (valid_vote, invalid_vote) = generate_opposing_votes_pair(
+				&test_state,
+				backer_index,
+				disabled_index,
+				candidate_hash,
+				session,
+				VoteType::Backing,
+			)
+			.await;
+
+			let (pending_confirmation, confirmation_rx) = oneshot::channel();
+			let pending_confirmation = Some(pending_confirmation);
+
+			// Scenario 1: unconfirmed dispute with onchain disabled validator against.
+			// Expectation: we import the vote, but do not participate.
+			virtual_overseer
+				.send(FromOrchestra::Communication {
+					msg: DisputeCoordinatorMessage::ImportStatements {
+						candidate_receipt: candidate_receipt.clone(),
+						session,
+						statements: vec![
+							(valid_vote, backer_index),
+							(invalid_vote, disabled_index),
+						],
+						pending_confirmation,
+					},
+				})
+				.await;
+
+			handle_disabled_validators_queries(&mut virtual_overseer, vec![disabled_index]).await;
+			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
+				.await;
+
+			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
+
+			// we should not participate due to disabled indices on chain
+			assert!(virtual_overseer.recv().timeout(TEST_TIMEOUT).await.is_none());
+
+			// Scenario 2: unconfirmed dispute with non-disabled validator against.
+			// Expectation: even if the dispute is unconfirmed, we should participate
+			// once we receive an invalid vote from a non-disabled validator.
+			let non_disabled_index = ValidatorIndex(3);
+			let vote = test_state.issue_explicit_statement_with_index(
+				non_disabled_index,
+				candidate_hash,
+				session,
+				false,
+			);
+			let statements = vec![(vote, non_disabled_index)];
+
+			let (pending_confirmation, confirmation_rx) = oneshot::channel();
+			let pending_confirmation = Some(pending_confirmation);
+
+			virtual_overseer
+				.send(FromOrchestra::Communication {
+					msg: DisputeCoordinatorMessage::ImportStatements {
+						candidate_receipt: candidate_receipt.clone(),
+						session,
+						statements,
+						pending_confirmation,
+					},
+				})
+				.await;
+
+			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
+
+			participation_with_distribution(
+				&mut virtual_overseer,
+				&candidate_hash,
+				candidate_receipt.commitments_hash,
+			)
+			.await;
+
+			{
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::ActiveDisputes(tx),
+					})
+					.await;
+
+				assert_eq!(rx.await.unwrap().len(), 1);
+
+				// check if we have participated (cast a vote)
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::QueryCandidateVotes(
+							vec![(session, candidate_hash)],
+							tx,
+						),
+					})
+					.await;
+
+				let (_, _, votes) = rx.await.unwrap().get(0).unwrap().clone();
+				assert_eq!(votes.valid.raw().len(), 2); // 3+1 => we have participated
+				assert_eq!(votes.invalid.len(), 2);
+			}
+
+			virtual_overseer.send(FromOrchestra::Signal(OverseerSignal::Conclude)).await;
+			assert!(virtual_overseer.try_recv().await.is_none());
+
+			test_state
+		})
+	});
+}
+
+#[test]
+fn participation_with_onchain_disabling_confirmed() {
+	test_harness(|mut test_state, mut virtual_overseer| {
+		Box::pin(async move {
+			let session = 1;
+
+			test_state.handle_resume_sync(&mut virtual_overseer, session).await;
+
+			let candidate_receipt = make_valid_candidate_receipt();
+			let candidate_hash = candidate_receipt.hash();
+			let events = vec![make_candidate_included_event(candidate_receipt.clone())];
+
+			test_state
+				.activate_leaf_at_session(&mut virtual_overseer, session, 1, events)
+				.await;
+
+			let backer_index = ValidatorIndex(1);
+			let disabled_index = ValidatorIndex(2);
+
+			// Scenario 1: confirmed dispute with disabled validator
+			// Expectation: we import the vote and participate.
+			let mut statements = Vec::new();
+
+			let (valid_vote, invalid_vote) = generate_opposing_votes_pair(
+				&test_state,
+				backer_index,
+				disabled_index,
+				candidate_hash,
+				session,
+				VoteType::Backing,
+			)
+			.await;
+
+			statements.push((valid_vote, backer_index));
+			statements.push((invalid_vote, disabled_index));
+
+			// now import enough votes for dispute confirmation
+			for i in vec![3, 4] {
+				let vote = test_state.issue_explicit_statement_with_index(
+					ValidatorIndex(i),
+					candidate_hash,
+					session,
+					true,
+				);
+
+				statements.push((vote, ValidatorIndex(i as _)));
+			}
+
+			let (pending_confirmation, confirmation_rx) = oneshot::channel();
+			let pending_confirmation = Some(pending_confirmation);
+
+			virtual_overseer
+				.send(FromOrchestra::Communication {
+					msg: DisputeCoordinatorMessage::ImportStatements {
+						candidate_receipt: candidate_receipt.clone(),
+						session,
+						statements,
+						pending_confirmation,
+					},
+				})
+				.await;
+
+			handle_disabled_validators_queries(&mut virtual_overseer, vec![]).await;
+			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
+				.await;
+			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
+
+			participation_with_distribution(
+				&mut virtual_overseer,
+				&candidate_hash,
+				candidate_receipt.commitments_hash,
+			)
+			.await;
+
+			{
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::ActiveDisputes(tx),
+					})
+					.await;
+
+				assert_eq!(rx.await.unwrap().len(), 1);
+
+				// check if we have participated (cast a vote)
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::QueryCandidateVotes(
+							vec![(session, candidate_hash)],
+							tx,
+						),
+					})
+					.await;
+
+				let (_, _, votes) = rx.await.unwrap().get(0).unwrap().clone();
+				assert_eq!(votes.valid.raw().len(), 4); // 3+1 => we have participated
+				assert_eq!(votes.invalid.len(), 1);
+			}
+
+			virtual_overseer.send(FromOrchestra::Signal(OverseerSignal::Conclude)).await;
+			assert!(virtual_overseer.try_recv().await.is_none());
+
+			test_state
+		})
+	});
+}
+
+#[test]
+fn participation_with_offchain_disabling() {
+	test_harness(|mut test_state, mut virtual_overseer| {
+		Box::pin(async move {
+			let session = 1;
+
+			test_state.handle_resume_sync(&mut virtual_overseer, session).await;
+
+			let candidate_receipt = make_valid_candidate_receipt();
+			let candidate_hash = candidate_receipt.hash();
+			let events = vec![make_candidate_included_event(candidate_receipt.clone())];
+
+			let block_hash = test_state
+				.activate_leaf_at_session(&mut virtual_overseer, session, 3, events)
+				.await;
+
+			let another_candidate_receipt = make_another_valid_candidate_receipt(block_hash);
+			let another_candidate_hash = another_candidate_receipt.hash();
+			let another_events =
+				vec![make_candidate_included_event(another_candidate_receipt.clone())];
+
+			test_state
+				.activate_leaf_at_session(&mut virtual_overseer, session, 4, another_events)
+				.await;
+
+			// import enough votes for supermajority to conclude the dispute
+			let mut statements = Vec::new();
+			let (valid_vote, invalid_vote) = generate_opposing_votes_pair(
+				&test_state,
+				ValidatorIndex(1),
+				ValidatorIndex(2),
+				candidate_hash,
+				session,
+				VoteType::Backing,
+			)
+			.await;
+
+			statements.push((valid_vote, ValidatorIndex(1)));
+			statements.push((invalid_vote, ValidatorIndex(2)));
+
+			for i in vec![3, 4, 5, 6, 7, 8] {
+				let vote = test_state.issue_explicit_statement_with_index(
+					ValidatorIndex(i),
+					candidate_hash,
+					session,
+					true,
+				);
+
+				statements.push((vote, ValidatorIndex(i as _)));
+			}
+
+			let (pending_confirmation, confirmation_rx) = oneshot::channel();
+			let pending_confirmation = Some(pending_confirmation);
+
+			virtual_overseer
+				.send(FromOrchestra::Communication {
+					msg: DisputeCoordinatorMessage::ImportStatements {
+						candidate_receipt: candidate_receipt.clone(),
+						session,
+						statements,
+						pending_confirmation,
+					},
+				})
+				.await;
+
+			handle_disabled_validators_queries(&mut virtual_overseer, vec![]).await;
+			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
+				.await;
+
+			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
+
+			participation_with_distribution(
+				&mut virtual_overseer,
+				&candidate_hash,
+				candidate_receipt.commitments_hash,
+			)
+			.await;
+
+			{
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::ActiveDisputes(tx),
+					})
+					.await;
+
+				assert_eq!(rx.await.unwrap().len(), 1);
+
+				// check if we have participated (cast a vote)
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::QueryCandidateVotes(
+							vec![(session, candidate_hash)],
+							tx,
+						),
+					})
+					.await;
+
+				let (_, _, votes) = rx.await.unwrap().get(0).unwrap().clone();
+				assert_eq!(votes.valid.raw().len(), 8); // 8 => we have participated
+				assert_eq!(votes.invalid.len(), 1);
+			}
+
+			// now create another dispute
+			// Validator 2 should be disabled offchain now
+
+			let mut statements = Vec::new();
+			let (valid_vote, invalid_vote) = generate_opposing_votes_pair(
+				&test_state,
+				ValidatorIndex(1),
+				ValidatorIndex(2),
+				another_candidate_hash,
+				session,
+				VoteType::Backing,
+			)
+			.await;
+
+			statements.push((valid_vote, ValidatorIndex(1)));
+			statements.push((invalid_vote, ValidatorIndex(2)));
+
+			let (pending_confirmation, confirmation_rx) = oneshot::channel();
+			let pending_confirmation = Some(pending_confirmation);
+
+			virtual_overseer
+				.send(FromOrchestra::Communication {
+					msg: DisputeCoordinatorMessage::ImportStatements {
+						candidate_receipt: another_candidate_receipt.clone(),
+						session,
+						statements,
+						pending_confirmation,
+					},
+				})
+				.await;
+
+			// let's disable validators 3, 4 on chain, but this should not affect this import
+			let disabled_validators = vec![ValidatorIndex(3), ValidatorIndex(4)];
+			handle_disabled_validators_queries(&mut virtual_overseer, disabled_validators).await;
+			handle_approval_vote_request(
+				&mut virtual_overseer,
+				&another_candidate_hash,
+				HashMap::new(),
+			)
+			.await;
+			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
+
+			// we should not participate since due to offchain disabling
+			assert!(virtual_overseer.recv().timeout(TEST_TIMEOUT).await.is_none());
+
+			// now import enough votes for dispute confirmation
+			// even though all of these votes are from (on chain) disabled validators
+			let mut statements = Vec::new();
+			for i in vec![3, 4] {
+				let vote = test_state.issue_explicit_statement_with_index(
+					ValidatorIndex(i),
+					another_candidate_hash,
+					session,
+					true,
+				);
+
+				statements.push((vote, ValidatorIndex(i as _)));
+			}
+
+			let (pending_confirmation, confirmation_rx) = oneshot::channel();
+			let pending_confirmation = Some(pending_confirmation);
+
+			virtual_overseer
+				.send(FromOrchestra::Communication {
+					msg: DisputeCoordinatorMessage::ImportStatements {
+						candidate_receipt: another_candidate_receipt.clone(),
+						session,
+						statements,
+						pending_confirmation,
+					},
+				})
+				.await;
+
+			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
+
+			participation_with_distribution(
+				&mut virtual_overseer,
+				&another_candidate_hash,
+				another_candidate_receipt.commitments_hash,
+			)
+			.await;
+
+			{
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::ActiveDisputes(tx),
+					})
+					.await;
+
+				assert_eq!(rx.await.unwrap().len(), 2);
+
+				// check if we have participated (cast a vote)
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::QueryCandidateVotes(
+							vec![(session, another_candidate_hash)],
+							tx,
+						),
+					})
+					.await;
+
+				let (_, _, votes) = rx.await.unwrap().get(0).unwrap().clone();
+				assert_eq!(votes.valid.raw().len(), 4); // 3+1 => we have participated
+				assert_eq!(votes.invalid.len(), 1);
+			}
+
+			virtual_overseer.send(FromOrchestra::Signal(OverseerSignal::Conclude)).await;
+			assert!(virtual_overseer.try_recv().await.is_none());
+
+			test_state
+		})
+	});
+}
+
+// Once the onchain disabling reaches the byzantine threshold,
+// offchain disabling will no longer take any effect.
+#[test]
+fn participation_with_disabling_limits() {
+	test_harness(|mut test_state, mut virtual_overseer| {
+		Box::pin(async move {
+			let session = 1;
+
+			test_state.handle_resume_sync(&mut virtual_overseer, session).await;
+
+			let candidate_receipt = make_valid_candidate_receipt();
+			let candidate_hash = candidate_receipt.hash();
+			let events = vec![make_candidate_included_event(candidate_receipt.clone())];
+
+			let block_hash = test_state
+				.activate_leaf_at_session(&mut virtual_overseer, session, 3, events)
+				.await;
+
+			let another_candidate_receipt = make_another_valid_candidate_receipt(block_hash);
+			let another_candidate_hash = another_candidate_receipt.hash();
+			let another_events =
+				vec![make_candidate_included_event(another_candidate_receipt.clone())];
+
+			test_state
+				.activate_leaf_at_session(&mut virtual_overseer, session, 4, another_events)
+				.await;
+
+			// import enough votes for supermajority to conclude the dispute
+			let mut statements = Vec::new();
+			let (valid_vote, invalid_vote) = generate_opposing_votes_pair(
+				&test_state,
+				ValidatorIndex(1),
+				ValidatorIndex(2),
+				candidate_hash,
+				session,
+				VoteType::Backing,
+			)
+			.await;
+
+			statements.push((valid_vote, ValidatorIndex(1)));
+			statements.push((invalid_vote, ValidatorIndex(2)));
+
+			for i in vec![3, 4, 5, 6, 7, 8] {
+				let vote = test_state.issue_explicit_statement_with_index(
+					ValidatorIndex(i),
+					candidate_hash,
+					session,
+					true,
+				);
+
+				statements.push((vote, ValidatorIndex(i as _)));
+			}
+
+			let (pending_confirmation, confirmation_rx) = oneshot::channel();
+			let pending_confirmation = Some(pending_confirmation);
+
+			virtual_overseer
+				.send(FromOrchestra::Communication {
+					msg: DisputeCoordinatorMessage::ImportStatements {
+						candidate_receipt: candidate_receipt.clone(),
+						session,
+						statements,
+						pending_confirmation,
+					},
+				})
+				.await;
+
+			handle_disabled_validators_queries(&mut virtual_overseer, vec![]).await;
+			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
+				.await;
+
+			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
+
+			participation_with_distribution(
+				&mut virtual_overseer,
+				&candidate_hash,
+				candidate_receipt.commitments_hash,
+			)
+			.await;
+
+			{
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::ActiveDisputes(tx),
+					})
+					.await;
+
+				assert_eq!(rx.await.unwrap().len(), 1);
+
+				// check if we have participated (cast a vote)
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::QueryCandidateVotes(
+							vec![(session, candidate_hash)],
+							tx,
+						),
+					})
+					.await;
+
+				let (_, _, votes) = rx.await.unwrap().get(0).unwrap().clone();
+				assert_eq!(votes.valid.raw().len(), 8); // 8 => we have participated
+				assert_eq!(votes.invalid.len(), 1);
+			}
+
+			// now create another dispute
+			// validator 2 should be disabled offchain now
+			// but due to the byzantine threshold of onchain disabling
+			// this validator will be considered enabled
+
+			let mut statements = Vec::new();
+			let (valid_vote, invalid_vote) = generate_opposing_votes_pair(
+				&test_state,
+				ValidatorIndex(1),
+				ValidatorIndex(2),
+				another_candidate_hash,
+				session,
+				VoteType::Backing,
+			)
+			.await;
+
+			statements.push((valid_vote, ValidatorIndex(1)));
+			statements.push((invalid_vote, ValidatorIndex(2)));
+
+			let (pending_confirmation, confirmation_rx) = oneshot::channel();
+			let pending_confirmation = Some(pending_confirmation);
+
+			virtual_overseer
+				.send(FromOrchestra::Communication {
+					msg: DisputeCoordinatorMessage::ImportStatements {
+						candidate_receipt: another_candidate_receipt.clone(),
+						session,
+						statements,
+						pending_confirmation,
+					},
+				})
+				.await;
+
+			// let's disable validators 3, 4, 5 on chain, reaching the byzantine threshold
+			let disabled_validators = vec![ValidatorIndex(3), ValidatorIndex(4), ValidatorIndex(5)];
+			handle_disabled_validators_queries(&mut virtual_overseer, disabled_validators).await;
+			handle_approval_vote_request(
+				&mut virtual_overseer,
+				&another_candidate_hash,
+				HashMap::new(),
+			)
+			.await;
+			assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
+
+			participation_with_distribution(
+				&mut virtual_overseer,
+				&another_candidate_hash,
+				another_candidate_receipt.commitments_hash,
+			)
+			.await;
+
+			{
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::ActiveDisputes(tx),
+					})
+					.await;
+
+				assert_eq!(rx.await.unwrap().len(), 2);
+
+				// check if we have participated (cast a vote)
+				let (tx, rx) = oneshot::channel();
+				virtual_overseer
+					.send(FromOrchestra::Communication {
+						msg: DisputeCoordinatorMessage::QueryCandidateVotes(
+							vec![(session, another_candidate_hash)],
+							tx,
+						),
+					})
+					.await;
+
+				let (_, _, votes) = rx.await.unwrap().get(0).unwrap().clone();
+				assert_eq!(votes.valid.raw().len(), 2); // 2 => we have participated
+				assert_eq!(votes.invalid.len(), 1);
+			}
+
+			virtual_overseer.send(FromOrchestra::Signal(OverseerSignal::Conclude)).await;
+			assert!(virtual_overseer.try_recv().await.is_none());
+
+			test_state
+		})
+	});
+}
+
 #[test]
 fn own_approval_vote_gets_distributed_on_dispute() {
 	test_harness(|mut test_state, mut virtual_overseer| {
@@ -2613,6 +3299,7 @@ fn own_approval_vote_gets_distributed_on_dispute() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -2667,6 +3354,7 @@ fn negative_issue_local_statement_only_triggers_import() {
 				})
 				.await;
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			// Assert that subsystem is not participating.
 			assert!(virtual_overseer.recv().timeout(TEST_TIMEOUT).await.is_none());
 
@@ -2732,6 +3420,7 @@ fn redundant_votes_ignored() {
 				})
 				.await;
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			rx.await.unwrap();
 
 			let (tx, rx) = oneshot::channel();
@@ -2806,6 +3495,7 @@ fn no_onesided_disputes() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			assert_matches!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
 
 			// We should not have any active disputes now.
@@ -2869,6 +3559,7 @@ fn refrain_from_participation() {
 				})
 				.await;
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -2961,6 +3652,7 @@ fn participation_for_included_candidates() {
 				})
 				.await;
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -3049,6 +3741,7 @@ fn local_participation_in_dispute_for_backed_candidate() {
 				})
 				.await;
 
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 
@@ -3190,6 +3883,7 @@ fn participation_requests_reprioritized_for_newly_included() {
 					})
 					.await;
 
+				handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 				// Handle corresponding messages to unblock import
 				// we need to handle `ApprovalVotingMessage::GetApprovalSignaturesForCandidate` for
 				// import
@@ -3343,6 +4037,7 @@ fn informs_chain_selection_when_dispute_concluded_against() {
 					},
 				})
 				.await;
+			handle_disabled_validators_queries(&mut virtual_overseer, Vec::new()).await;
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;
 			assert_matches!(confirmation_rx.await.unwrap(),
@@ -3655,3 +4350,27 @@ fn session_info_small_jump_works() {
 		})
 	});
 }
+
+async fn handle_disabled_validators_queries(
+	virtual_overseer: &mut VirtualOverseer,
+	disabled_validators: Vec<ValidatorIndex>,
+) {
+	assert_matches!(
+		virtual_overseer.recv().await,
+		AllMessages::RuntimeApi(RuntimeApiMessage::Request(
+			_new_leaf,
+			RuntimeApiRequest::Version(tx),
+		)) => {
+			tx.send(Ok(RuntimeApiRequest::DISABLED_VALIDATORS_RUNTIME_REQUIREMENT)).unwrap();
+		}
+	);
+	assert_matches!(
+		virtual_overseer.recv().await,
+		AllMessages::RuntimeApi(RuntimeApiMessage::Request(
+			_new_leaf,
+			RuntimeApiRequest::DisabledValidators(tx),
+		)) => {
+			tx.send(Ok(disabled_validators)).unwrap();
+		}
+	);
+}