Fix PVF precompilation for Kusama (#5606)

![image](https://github.com/user-attachments/assets/2deaee85-67c3-4119-b0c0-d2e7f818b4ea)

Because on Kusama validators.len() < discovery_keys.len() we can tweak
the PVF precompilation to allow prepare PVFs when the node is an
authority but not a validator.

polkadot/node/core/candidate-validation/src/lib.rs

@@ -47,7 +47,7 @@ use polkadot_primitives::{
 	},
 	AuthorityDiscoveryId, CandidateCommitments, CandidateDescriptor, CandidateEvent,
 	CandidateReceipt, ExecutorParams, Hash, OccupiedCoreAssumption, PersistedValidationData,
-	PvfExecKind, PvfPrepKind, SessionIndex, ValidationCode, ValidationCodeHash,
+	PvfExecKind, PvfPrepKind, SessionIndex, ValidationCode, ValidationCodeHash, ValidatorId,
 };
 use sp_application_crypto::{AppCrypto, ByteArray};
 use sp_keystore::KeystorePtr;
@@ -427,14 +427,15 @@ where
 		.iter()
 		.any(|v| keystore.has_keys(&[(v.to_raw_vec(), AuthorityDiscoveryId::ID)]));
 
-	let is_present_authority = session_info
-		.discovery_keys
+	// We could've checked discovery_keys but on Kusama validators.len() < discovery_keys.len().
+	let is_present_validator = session_info
+		.validators
 		.iter()
-		.any(|v| keystore.has_keys(&[(v.to_raw_vec(), AuthorityDiscoveryId::ID)]));
+		.any(|v| keystore.has_keys(&[(v.to_raw_vec(), ValidatorId::ID)]));
 
 	// There is still a chance to be a previous session authority, but this extra work does not
 	// affect the finalization.
-	is_past_present_or_future_authority && !is_present_authority
+	is_past_present_or_future_authority && !is_present_validator
 }
 
 // Sends PVF with unknown code hashes to the validation host returning the list of code hashes sent.

polkadot/node/core/candidate-validation/src/tests.rs

@@ -25,13 +25,12 @@ use polkadot_node_subsystem::messages::AllMessages;
 use polkadot_node_subsystem_util::reexports::SubsystemContext;
 use polkadot_overseer::ActivatedLeaf;
 use polkadot_primitives::{
-	CoreIndex, GroupIndex, HeadData, Id as ParaId, IndexedVec, SessionInfo, UpwardMessage,
-	ValidatorId, ValidatorIndex,
+	CoreIndex, GroupIndex, HeadData, Id as ParaId, SessionInfo, UpwardMessage, ValidatorId,
 };
 use polkadot_primitives_test_helpers::{
 	dummy_collator, dummy_collator_signature, dummy_hash, make_valid_candidate_descriptor,
 };
-use sp_core::testing::TaskExecutor;
+use sp_core::{sr25519::Public, testing::TaskExecutor};
 use sp_keyring::Sr25519Keyring;
 use sp_keystore::{testing::MemoryKeystore, Keystore};
 
@@ -1194,10 +1193,10 @@ fn dummy_candidate_backed(
 	)
 }
 
-fn dummy_session_info(discovery_keys: Vec<AuthorityDiscoveryId>) -> SessionInfo {
+fn dummy_session_info(keys: Vec<Public>) -> SessionInfo {
 	SessionInfo {
-		validators: IndexedVec::<ValidatorIndex, ValidatorId>::from(vec![]),
-		discovery_keys,
+		validators: keys.iter().cloned().map(Into::into).collect(),
+		discovery_keys: keys.iter().cloned().map(Into::into).collect(),
 		assignment_keys: vec![],
 		validator_groups: Default::default(),
 		n_cores: 4u32,
@@ -1246,7 +1245,7 @@ fn maybe_prepare_validation_golden_path() {
 			ctx_handle.recv().await,
 			AllMessages::RuntimeApi(RuntimeApiMessage::Request(_, RuntimeApiRequest::SessionInfo(index, tx))) => {
 				assert_eq!(index, 1);
-				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Bob.public().into()]))));
+				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Bob.public()]))));
 			}
 		);
 
@@ -1364,7 +1363,7 @@ fn maybe_prepare_validation_resets_state_on_a_new_session() {
 			ctx_handle.recv().await,
 			AllMessages::RuntimeApi(RuntimeApiMessage::Request(_, RuntimeApiRequest::SessionInfo(index, tx))) => {
 				assert_eq!(index, 2);
-				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Bob.public().into()]))));
+				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Bob.public()]))));
 			}
 		);
 	};
@@ -1510,7 +1509,7 @@ fn maybe_prepare_validation_does_not_prepare_pvfs_if_not_a_validator_in_the_next
 			ctx_handle.recv().await,
 			AllMessages::RuntimeApi(RuntimeApiMessage::Request(_, RuntimeApiRequest::SessionInfo(index, tx))) => {
 				assert_eq!(index, 1);
-				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Bob.public().into()]))));
+				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Bob.public()]))));
 			}
 		);
 	};
@@ -1557,7 +1556,7 @@ fn maybe_prepare_validation_does_not_prepare_pvfs_if_a_validator_in_the_current_
 			ctx_handle.recv().await,
 			AllMessages::RuntimeApi(RuntimeApiMessage::Request(_, RuntimeApiRequest::SessionInfo(index, tx))) => {
 				assert_eq!(index, 1);
-				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Alice.public().into()]))));
+				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Alice.public()]))));
 			}
 		);
 	};
@@ -1604,7 +1603,7 @@ fn maybe_prepare_validation_prepares_a_limited_number_of_pvfs() {
 			ctx_handle.recv().await,
 			AllMessages::RuntimeApi(RuntimeApiMessage::Request(_, RuntimeApiRequest::SessionInfo(index, tx))) => {
 				assert_eq!(index, 1);
-				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Bob.public().into()]))));
+				let _ = tx.send(Ok(Some(dummy_session_info(vec![Sr25519Keyring::Bob.public()]))));
 			}
 		);
 

prdoc/pr_5606.prdoc

@@ -0,0 +1,13 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Fix PVF precompilation for Kusama
+
+doc:
+  - audience: Node Operator
+    description: |
+      Tweaks the PVF precompilation on Kusama to allow prepare PVFs when the node is an authority but not a validator.
+
+crates:
+  - name: polkadot-node-core-candidate-validation
+    bump: patch