refactor(levm): decluttering vm.rs (#2733)

**Motivation**

Making the code of the vm.rs file cleaner, since it's a bit cluttered
right now.

**Description**

The code of vm.rs is a bit messy right now. This PR moves EVM config to
environment, moves a few attributes from environment to substate that
make more sense there, and removes the StateBackup struct since it's
made unnecessary by this change.

Closes #2731, Closes #2717 
Resolves most of #2718

---------

Co-authored-by: JereSalo <[email protected]>

Author: SDartayet

cmd/ef_tests/state/runner/levm_runner.rs

@@ -11,14 +11,13 @@ use ethrex_common::{
 use ethrex_levm::{
     db::gen_db::GeneralizedDatabase,
     errors::{ExecutionReport, TxValidationError, VMError},
-    vm::{EVMConfig, VM},
-    Environment,
+    vm::VM,
+    EVMConfig, Environment,
 };
 use ethrex_rlp::encode::RLPEncode;
 use ethrex_storage::AccountUpdate;
 use ethrex_vm::backends;
 use keccak_hash::keccak;
-use std::collections::HashMap;
 
 pub async fn run_ef_test(test: &EFTest) -> Result<EFTestReport, EFTestRunnerError> {
     // There are some tests that don't have a hash, unwrap will panic
@@ -168,7 +167,6 @@ pub fn prepare_vm_for_tx<'a>(
     VM::new(
         Environment {
             origin: test_tx.sender,
-            refunded_gas: 0,
             gas_limit: test_tx.gas_limit,
             config,
             block_number: test.env.current_number,
@@ -187,7 +185,6 @@ pub fn prepare_vm_for_tx<'a>(
             tx_max_fee_per_blob_gas: test_tx.max_fee_per_blob_gas,
             tx_nonce: test_tx.nonce,
             block_gas_limit: test.env.current_gas_limit,
-            transient_storage: HashMap::new(),
             is_privileged: false,
         },
         db,

crates/vm/backends/levm/mod.rs

@@ -19,9 +19,10 @@ use ethrex_common::{
 };
 use ethrex_levm::db::gen_db::GeneralizedDatabase;
 use ethrex_levm::errors::TxValidationError;
+use ethrex_levm::EVMConfig;
 use ethrex_levm::{
     errors::{ExecutionReport, TxResult, VMError},
-    vm::{EVMConfig, Substate, VM},
+    vm::{Substate, VM},
     Environment,
 };
 use ethrex_storage::error::StoreError;
@@ -115,7 +116,6 @@ impl LEVM {
         let config = EVMConfig::new_from_chain_config(&chain_config, block_header);
         let env = Environment {
             origin: tx_sender,
-            refunded_gas: 0,
             gas_limit: tx.gas_limit(),
             config,
             block_number: block_header.number.into(),
@@ -133,7 +133,6 @@ impl LEVM {
             tx_max_fee_per_blob_gas: tx.max_fee_per_blob_gas().map(U256::from),
             tx_nonce: tx.nonce(),
             block_gas_limit: block_header.gas_limit,
-            transient_storage: HashMap::new(),
             difficulty: block_header.difficulty,
             is_privileged: matches!(tx, Transaction::PrivilegedL2Transaction(_)),
         };
@@ -593,7 +592,6 @@ pub fn generic_system_contract_levm(
         block_excess_blob_gas: block_header.excess_blob_gas.map(U256::from),
         block_blob_gas_used: block_header.blob_gas_used.map(U256::from),
         block_gas_limit: 30_000_000,
-        transient_storage: HashMap::new(),
         config,
         ..Default::default()
     };
@@ -708,7 +706,6 @@ fn env_from_generic(
     let config = EVMConfig::new_from_chain_config(&chain_config, header);
     Ok(Environment {
         origin: tx.from.0.into(),
-        refunded_gas: 0,
         gas_limit: tx.gas.unwrap_or(header.gas_limit), // Ensure tx doesn't fail due to gas limit
         config,
         block_number: header.number.into(),
@@ -726,7 +723,6 @@ fn env_from_generic(
         tx_max_fee_per_blob_gas: tx.max_fee_per_blob_gas,
         tx_nonce: tx.nonce.unwrap_or_default(),
         block_gas_limit: header.gas_limit,
-        transient_storage: HashMap::new(),
         difficulty: header.difficulty,
         is_privileged: false,
     })

crates/vm/levm/src/environment.rs

@@ -1,6 +1,12 @@
-use ethrex_common::{Address, H256, U256};
+use ethrex_common::{
+    types::{BlockHeader, ChainConfig, Fork, ForkBlobSchedule},
+    Address, H256, U256,
+};
 
-use crate::vm::EVMConfig;
+use crate::constants::{
+    BLOB_BASE_FEE_UPDATE_FRACTION, BLOB_BASE_FEE_UPDATE_FRACTION_PRAGUE, MAX_BLOB_COUNT,
+    MAX_BLOB_COUNT_ELECTRA, TARGET_BLOB_GAS_PER_BLOCK, TARGET_BLOB_GAS_PER_BLOCK_PECTRA,
+};
 
 use std::collections::HashMap;
 /// [EIP-1153]: https://eips.ethereum.org/EIPS/eip-1153#reference-implementation
@@ -11,7 +17,6 @@ pub type TransientStorage = HashMap<(Address, U256), U256>;
 pub struct Environment {
     /// The sender address of the external transaction.
     pub origin: Address,
-    pub refunded_gas: u64,
     /// Gas limit of the Transaction
     pub gas_limit: u64,
     pub config: EVMConfig,
@@ -32,6 +37,89 @@ pub struct Environment {
     pub tx_max_fee_per_blob_gas: Option<U256>,
     pub tx_nonce: u64,
     pub block_gas_limit: u64,
-    pub transient_storage: TransientStorage,
     pub is_privileged: bool,
 }
+
+#[derive(Debug, Clone, Copy)]
+/// This struct holds special configuration variables specific to the
+/// EVM. In most cases, at least at the time of writing (February
+/// 2025), you want to use the default blob_schedule values for the
+/// specified Fork. The "intended" way to do this is by using the `EVMConfig::canonical_values(fork: Fork)` function.
+///
+/// However, that function should NOT be used IF you want to use a
+/// custom `ForkBlobSchedule`, like it's described in [EIP-7840](https://eips.ethereum.org/EIPS/eip-7840)
+/// Values are determined by [EIP-7691](https://eips.ethereum.org/EIPS/eip-7691#specification)
+pub struct EVMConfig {
+    pub fork: Fork,
+    pub blob_schedule: ForkBlobSchedule,
+}
+
+impl EVMConfig {
+    pub fn new(fork: Fork, blob_schedule: ForkBlobSchedule) -> EVMConfig {
+        EVMConfig {
+            fork,
+            blob_schedule,
+        }
+    }
+
+    pub fn new_from_chain_config(chain_config: &ChainConfig, block_header: &BlockHeader) -> Self {
+        let fork = chain_config.fork(block_header.timestamp);
+
+        let blob_schedule = chain_config
+            .get_fork_blob_schedule(block_header.timestamp)
+            .unwrap_or_else(|| EVMConfig::canonical_values(fork));
+
+        EVMConfig::new(fork, blob_schedule)
+    }
+
+    /// This function is used for running the EF tests. If you don't
+    /// have acces to a EVMConfig (mainly in the form of a
+    /// genesis.json file) you can use this function to get the
+    /// "Default" ForkBlobSchedule for that specific Fork.
+    /// NOTE: This function could potentially be expanded to include
+    /// other types of "default"s.
+    pub fn canonical_values(fork: Fork) -> ForkBlobSchedule {
+        let max_blobs_per_block: u64 = Self::max_blobs_per_block(fork);
+        let target: u64 = Self::get_target_blob_gas_per_block_(fork);
+        let base_fee_update_fraction: u64 = Self::get_blob_base_fee_update_fraction_value(fork);
+
+        ForkBlobSchedule {
+            target,
+            max: max_blobs_per_block,
+            base_fee_update_fraction,
+        }
+    }
+
+    const fn max_blobs_per_block(fork: Fork) -> u64 {
+        match fork {
+            Fork::Prague => MAX_BLOB_COUNT_ELECTRA,
+            Fork::Osaka => MAX_BLOB_COUNT_ELECTRA,
+            _ => MAX_BLOB_COUNT,
+        }
+    }
+
+    const fn get_blob_base_fee_update_fraction_value(fork: Fork) -> u64 {
+        match fork {
+            Fork::Prague | Fork::Osaka => BLOB_BASE_FEE_UPDATE_FRACTION_PRAGUE,
+            _ => BLOB_BASE_FEE_UPDATE_FRACTION,
+        }
+    }
+
+    const fn get_target_blob_gas_per_block_(fork: Fork) -> u64 {
+        match fork {
+            Fork::Prague | Fork::Osaka => TARGET_BLOB_GAS_PER_BLOCK_PECTRA,
+            _ => TARGET_BLOB_GAS_PER_BLOCK,
+        }
+    }
+}
+
+impl Default for EVMConfig {
+    /// The default EVMConfig depends on the default Fork.
+    fn default() -> Self {
+        let fork = core::default::Default::default();
+        EVMConfig {
+            fork,
+            blob_schedule: Self::canonical_values(fork),
+        }
+    }
+}

crates/vm/levm/src/execution_handlers.rs

@@ -5,7 +5,7 @@ use crate::{
     gas_cost::CODE_DEPOSIT_COST,
     opcodes::Opcode,
     utils::*,
-    vm::{StateBackup, VM},
+    vm::{Substate, VM},
 };
 
 use bytes::Bytes;
@@ -14,14 +14,14 @@ impl<'a> VM<'a> {
     pub fn handle_precompile_result(
         &mut self,
         precompile_result: Result<Bytes, VMError>,
-        backup: StateBackup,
+        backup: Substate,
         current_call_frame: &mut CallFrame,
     ) -> Result<ExecutionReport, VMError> {
         match precompile_result {
             Ok(output) => Ok(ExecutionReport {
                 result: TxResult::Success,
                 gas_used: current_call_frame.gas_used,
-                gas_refunded: self.env.refunded_gas,
+                gas_refunded: self.accrued_substate.refunded_gas,
                 output,
                 logs: std::mem::take(&mut current_call_frame.logs),
             }),
@@ -35,7 +35,7 @@ impl<'a> VM<'a> {
                 Ok(ExecutionReport {
                     result: TxResult::Revert(error),
                     gas_used: current_call_frame.gas_limit,
-                    gas_refunded: self.env.refunded_gas,
+                    gas_refunded: self.accrued_substate.refunded_gas,
                     output: Bytes::new(),
                     logs: vec![],
                 })
@@ -153,7 +153,7 @@ impl<'a> VM<'a> {
         executed_call_frame: &mut CallFrame,
     ) -> Result<ExecutionReport, VMError> {
         let backup = self
-            .backups
+            .substate_backups
             .pop()
             .ok_or(VMError::Internal(InternalError::CouldNotPopCallframe))?;
         // On successful create check output validity
@@ -207,7 +207,7 @@ impl<'a> VM<'a> {
                     return Ok(ExecutionReport {
                         result: TxResult::Revert(error),
                         gas_used: executed_call_frame.gas_used,
-                        gas_refunded: self.env.refunded_gas,
+                        gas_refunded: self.accrued_substate.refunded_gas,
                         output: std::mem::take(&mut executed_call_frame.output),
                         logs: vec![],
                     });
@@ -218,7 +218,7 @@ impl<'a> VM<'a> {
         Ok(ExecutionReport {
             result: TxResult::Success,
             gas_used: executed_call_frame.gas_used,
-            gas_refunded: self.env.refunded_gas,
+            gas_refunded: self.accrued_substate.refunded_gas,
             output: std::mem::take(&mut executed_call_frame.output),
             logs: std::mem::take(&mut executed_call_frame.logs),
         })
@@ -230,7 +230,7 @@ impl<'a> VM<'a> {
         executed_call_frame: &mut CallFrame,
     ) -> Result<ExecutionReport, VMError> {
         let backup = self
-            .backups
+            .substate_backups
             .pop()
             .ok_or(VMError::Internal(InternalError::CouldNotPopCallframe))?;
         if error.should_propagate() {

crates/vm/levm/src/opcode_handlers/stack_memory_storage_flow.rs

@@ -30,7 +30,7 @@ impl<'a> VM<'a> {
         let key = self.current_call_frame_mut()?.stack.pop()?;
         let to = self.current_call_frame()?.to;
         let value = self
-            .env
+            .accrued_substate
             .transient_storage
             .get(&(to, key))
             .cloned()
@@ -63,7 +63,9 @@ impl<'a> VM<'a> {
             let value = current_call_frame.stack.pop()?;
             (key, value, current_call_frame.to)
         };
-        self.env.transient_storage.insert((to, key), value);
+        self.accrued_substate
+            .transient_storage
+            .insert((to, key), value);
 
         Ok(OpcodeResult::Continue { pc_increment: 1 })
     }
@@ -186,7 +188,7 @@ impl<'a> VM<'a> {
 
         // Gas Refunds
         // Sync gas refund with global env, ensuring consistency accross contexts.
-        let mut gas_refunds = self.env.refunded_gas;
+        let mut gas_refunds = self.accrued_substate.refunded_gas;
 
         // https://eips.ethereum.org/EIPS/eip-2929
         let (remove_slot_cost, restore_empty_slot_cost, restore_slot_cost) = (4800, 19900, 2800);
@@ -224,7 +226,7 @@ impl<'a> VM<'a> {
             }
         }
 
-        self.env.refunded_gas = gas_refunds;
+        self.accrued_substate.refunded_gas = gas_refunds;
 
         self.current_call_frame_mut()?
             .increase_consumed_gas(gas_cost::sstore(

crates/vm/levm/src/opcode_handlers/system.rs

@@ -7,7 +7,7 @@ use crate::{
     memory::{self, calculate_memory_size},
     precompiles::is_precompile,
     utils::{address_to_word, word_to_address, *},
-    vm::{StateBackup, VM},
+    vm::VM,
 };
 use bytes::Bytes;
 use ethrex_common::{
@@ -725,13 +725,10 @@ impl<'a> VM<'a> {
 
         self.accrued_substate.created_accounts.insert(new_address); // Mostly for SELFDESTRUCT during initcode.
 
-        // Backup of Database, Substate, Gas Refunds and Transient Storage if sub-context is reverted
-        let backup = StateBackup::new(
-            self.accrued_substate.clone(),
-            self.env.refunded_gas,
-            self.env.transient_storage.clone(),
-        );
-        self.backups.push(backup);
+        // Backup of Substate, a copy of the substate to restore if sub-context is reverted
+        let backup = self.accrued_substate.clone();
+        self.substate_backups.push(backup);
+
         Ok(OpcodeResult::Continue { pc_increment: 0 })
     }
 
@@ -831,13 +828,9 @@ impl<'a> VM<'a> {
             ret_size,
         );
         self.call_frames.push(new_call_frame);
-        // Backup of Database, Substate, Gas Refunds and Transient Storage if sub-context is reverted
-        let backup = StateBackup::new(
-            self.accrued_substate.clone(),
-            self.env.refunded_gas,
-            self.env.transient_storage.clone(),
-        );
-        self.backups.push(backup);
+        // Backup of Substate, a copy of the substate to restore if sub-context is reverted
+        let backup = self.accrued_substate.clone();
+        self.substate_backups.push(backup);
 
         if is_precompile(&code_address, self.env.config.fork) {
             let _report = self.run_execution()?;

crates/vm/levm/src/utils.rs

@@ -8,7 +8,8 @@ use crate::{
         TOTAL_COST_FLOOR_PER_TOKEN, WARM_ADDRESS_ACCESS_COST,
     },
     opcodes::Opcode,
-    vm::{EVMConfig, Substate, VM},
+    vm::{Substate, VM},
+    EVMConfig,
 };
 use bytes::Bytes;
 use ethrex_common::types::Account;
@@ -462,7 +463,7 @@ impl<'a> VM<'a> {
         self.current_call_frame_mut()?.valid_jump_destinations =
             get_valid_jump_destinations(&self.current_call_frame()?.bytecode).unwrap_or_default();
 
-        self.env.refunded_gas = refunded_gas;
+        self.accrued_substate.refunded_gas = refunded_gas;
 
         Ok(())
     }