add runtime migration

node/core/backing/src/lib.rs

@@ -1000,6 +1000,7 @@ async fn construct_per_relay_parent_state<Context>(
 		try_runtime_api!(runtime_info.get_session_index_for_child(ctx.sender(), parent).await);
 	let minimum_backing_votes =
 		runtime_info.get_min_backing_votes(ctx.sender(), session_index, parent).await;
+	// TODO: if this does not exist, fall back to the hardcoded 2 value.
 
 	let (validators, groups, cores) = futures::try_join!(
 		request_validators(parent, ctx.sender()).await,

node/core/runtime-api/src/tests.rs

@@ -264,6 +264,10 @@ impl RuntimeApiSubsystemClient for MockSubsystemClient {
 	) -> Result<Option<vstaging::BackingState>, ApiError> {
 		todo!("Not required for tests")
 	}
+
+	async fn minimum_backing_votes(&self, _: Hash) -> Result<u32, ApiError> {
+		todo!("Not required for tests")
+	}
 }
 
 #[test]

primitives/src/runtime_api.rs

@@ -241,6 +241,7 @@ sp_api::decl_runtime_apis! {
 		) -> Option<()>;
 
 		/// Get the minimum number of backing votes for a parachain candidate.
+		/// TODO: bump api version here?
 		fn minimum_backing_votes() -> u32;
 
 		/***** Asynchronous backing *****/

runtime/kusama/src/lib.rs

@@ -1606,6 +1606,7 @@ pub mod migrations {
 		frame_support::migrations::RemovePallet<TechnicalMembershipPalletName, <Runtime as frame_system::Config>::DbWeight>,
 		frame_support::migrations::RemovePallet<TipsPalletName, <Runtime as frame_system::Config>::DbWeight>,
 
+		parachains_configuration::migration::v9::MigrateToV9<Runtime>,
 	);
 }
 

runtime/parachains/src/configuration.rs

@@ -295,7 +295,7 @@ impl<BlockNumber: Default + From<u32>> Default for HostConfiguration<BlockNumber
 			on_demand_fee_variability: Perbill::from_percent(3),
 			on_demand_target_queue_utilization: Perbill::from_percent(25),
 			on_demand_ttl: 5u32.into(),
-			minimum_backing_votes: Default::default(),
+			minimum_backing_votes: 2,
 		}
 	}
 }
@@ -478,7 +478,8 @@ pub mod pallet {
 	/// v5-v6: <https://github.com/paritytech/polkadot/pull/6271> (remove UMP dispatch queue)
 	/// v6-v7: <https://github.com/paritytech/polkadot/pull/7396>
 	/// v7-v8: <https://github.com/paritytech/polkadot/pull/6969>
-	const STORAGE_VERSION: StorageVersion = StorageVersion::new(8);
+	/// v8-v9: <https://github.com/paritytech/polkadot/pull/7577>
+	const STORAGE_VERSION: StorageVersion = StorageVersion::new(9);
 
 	#[pallet::pallet]
 	#[pallet::storage_version(STORAGE_VERSION)]
@@ -1154,6 +1155,18 @@ pub mod pallet {
 				config.on_demand_ttl = new;
 			})
 		}
+		/// Set the minimum backing votes threshold.
+		#[pallet::call_index(52)]
+		#[pallet::weight((
+			T::WeightInfo::set_config_with_u32(),
+			DispatchClass::Operational
+		))]
+		pub fn set_minimum_backing_votes(origin: OriginFor<T>, new: u32) -> DispatchResult {
+			ensure_root(origin)?;
+			Self::schedule_config_update(|config| {
+				config.minimum_backing_votes = new;
+			})
+		}
 	}
 
 	#[pallet::hooks]

runtime/parachains/src/configuration/migration.rs

@@ -19,3 +19,4 @@
 pub mod v6;
 pub mod v7;
 pub mod v8;
+pub mod v9;

runtime/parachains/src/configuration/migration/v8.rs

@@ -23,14 +23,114 @@ use frame_support::{
 	weights::Weight,
 };
 use frame_system::pallet_prelude::BlockNumberFor;
-use primitives::SessionIndex;
+use primitives::{
+	vstaging::AsyncBackingParams, Balance, ExecutorParams, SessionIndex,
+	ON_DEMAND_DEFAULT_QUEUE_MAX_SIZE,
+};
 use sp_runtime::Perbill;
 use sp_std::vec::Vec;
 
 use frame_support::traits::OnRuntimeUpgrade;
 
 use super::v7::V7HostConfiguration;
-type V8HostConfiguration<BlockNumber> = configuration::HostConfiguration<BlockNumber>;
+/// All configuration of the runtime with respect to paras.
+#[derive(Clone, Encode, Decode, Debug)]
+pub struct V8HostConfiguration<BlockNumber> {
+	pub max_code_size: u32,
+	pub max_head_data_size: u32,
+	pub max_upward_queue_count: u32,
+	pub max_upward_queue_size: u32,
+	pub max_upward_message_size: u32,
+	pub max_upward_message_num_per_candidate: u32,
+	pub hrmp_max_message_num_per_candidate: u32,
+	pub validation_upgrade_cooldown: BlockNumber,
+	pub validation_upgrade_delay: BlockNumber,
+	pub async_backing_params: AsyncBackingParams,
+	pub max_pov_size: u32,
+	pub max_downward_message_size: u32,
+	pub hrmp_max_parachain_outbound_channels: u32,
+	pub hrmp_sender_deposit: Balance,
+	pub hrmp_recipient_deposit: Balance,
+	pub hrmp_channel_max_capacity: u32,
+	pub hrmp_channel_max_total_size: u32,
+	pub hrmp_max_parachain_inbound_channels: u32,
+	pub hrmp_channel_max_message_size: u32,
+	pub executor_params: ExecutorParams,
+	pub code_retention_period: BlockNumber,
+	pub on_demand_cores: u32,
+	pub on_demand_retries: u32,
+	pub on_demand_queue_max_size: u32,
+	pub on_demand_target_queue_utilization: Perbill,
+	pub on_demand_fee_variability: Perbill,
+	pub on_demand_base_fee: Balance,
+	pub on_demand_ttl: BlockNumber,
+	pub group_rotation_frequency: BlockNumber,
+	pub paras_availability_period: BlockNumber,
+	pub scheduling_lookahead: u32,
+	pub max_validators_per_core: Option<u32>,
+	pub max_validators: Option<u32>,
+	pub dispute_period: SessionIndex,
+	pub dispute_post_conclusion_acceptance_period: BlockNumber,
+	pub no_show_slots: u32,
+	pub n_delay_tranches: u32,
+	pub zeroth_delay_tranche_width: u32,
+	pub needed_approvals: u32,
+	pub relay_vrf_modulo_samples: u32,
+	pub pvf_voting_ttl: SessionIndex,
+	pub minimum_validation_upgrade_delay: BlockNumber,
+}
+
+impl<BlockNumber: Default + From<u32>> Default for V8HostConfiguration<BlockNumber> {
+	fn default() -> Self {
+		Self {
+			async_backing_params: AsyncBackingParams {
+				max_candidate_depth: 0,
+				allowed_ancestry_len: 0,
+			},
+			group_rotation_frequency: 1u32.into(),
+			paras_availability_period: 1u32.into(),
+			no_show_slots: 1u32.into(),
+			validation_upgrade_cooldown: Default::default(),
+			validation_upgrade_delay: 2u32.into(),
+			code_retention_period: Default::default(),
+			max_code_size: Default::default(),
+			max_pov_size: Default::default(),
+			max_head_data_size: Default::default(),
+			on_demand_cores: Default::default(),
+			on_demand_retries: Default::default(),
+			scheduling_lookahead: 1,
+			max_validators_per_core: Default::default(),
+			max_validators: None,
+			dispute_period: 6,
+			dispute_post_conclusion_acceptance_period: 100.into(),
+			n_delay_tranches: Default::default(),
+			zeroth_delay_tranche_width: Default::default(),
+			needed_approvals: Default::default(),
+			relay_vrf_modulo_samples: Default::default(),
+			max_upward_queue_count: Default::default(),
+			max_upward_queue_size: Default::default(),
+			max_downward_message_size: Default::default(),
+			max_upward_message_size: Default::default(),
+			max_upward_message_num_per_candidate: Default::default(),
+			hrmp_sender_deposit: Default::default(),
+			hrmp_recipient_deposit: Default::default(),
+			hrmp_channel_max_capacity: Default::default(),
+			hrmp_channel_max_total_size: Default::default(),
+			hrmp_max_parachain_inbound_channels: Default::default(),
+			hrmp_channel_max_message_size: Default::default(),
+			hrmp_max_parachain_outbound_channels: Default::default(),
+			hrmp_max_message_num_per_candidate: Default::default(),
+			pvf_voting_ttl: 2u32.into(),
+			minimum_validation_upgrade_delay: 2.into(),
+			executor_params: Default::default(),
+			on_demand_queue_max_size: ON_DEMAND_DEFAULT_QUEUE_MAX_SIZE,
+			on_demand_base_fee: 10_000_000u128,
+			on_demand_fee_variability: Perbill::from_percent(3),
+			on_demand_target_queue_utilization: Perbill::from_percent(25),
+			on_demand_ttl: 5u32.into(),
+		}
+	}
+}
 
 mod v7 {
 	use super::*;
@@ -150,7 +250,6 @@ on_demand_base_fee                       : 10_000_000u128,
 on_demand_fee_variability                : Perbill::from_percent(3),
 on_demand_target_queue_utilization       : Perbill::from_percent(25),
 on_demand_ttl                            : 5u32.into(),
-minimum_backing_votes                    : 2
 		}
 	};