Add instruction to update the LTV of a reserve

token-lending/program/src/instruction.rs

@@ -362,6 +362,22 @@ pub enum LendingInstruction {
         /// liquidity_amount is the amount of collateral tokens to withdraw
         collateral_amount: u64,
     },
+
+    // 16
+    /// Updates a reserve config parameter
+    ///
+    /// Accounts expected by this instruction:
+    ///
+    ///   1. `[writable]` Reserve account - refreshed
+    ///   2 `[]` Lending market account.
+    ///   3 `[]` Derived lending market authority.
+    ///   4 `[signer]` Lending market owner.
+    UpdateReserveConfig {
+        /// Specifies which config to change
+        config_enum: u8,
+        /// New value for the config
+        new_value: u8,
+    },
 }
 
 impl LendingInstruction {
@@ -456,6 +472,14 @@ impl LendingInstruction {
                 let (collateral_amount, _rest) = Self::unpack_u64(rest)?;
                 Self::WithdrawObligationCollateralAndRedeemReserveCollateral { collateral_amount }
             }
+            16 => {
+                let (config_enum, _rest) = Self::unpack_u8(rest)?;
+                let (new_value, _rest) = Self::unpack_u8(_rest)?;
+                Self::UpdateReserveConfig {
+                    config_enum,
+                    new_value,
+                }
+            }
             _ => {
                 msg!("Instruction cannot be unpacked");
                 return Err(LendingError::InstructionUnpackError.into());
@@ -612,6 +636,14 @@ impl LendingInstruction {
                 buf.push(15);
                 buf.extend_from_slice(&collateral_amount.to_le_bytes());
             }
+            Self::UpdateReserveConfig {
+                config_enum,
+                new_value,
+            } => {
+                buf.push(16);
+                buf.extend_from_slice(&config_enum.to_le_bytes());
+                buf.extend_from_slice(&new_value.to_le_bytes());
+            }
         }
         buf
     }

token-lending/program/src/processor.rs

@@ -9,7 +9,7 @@ use crate::{
         CalculateBorrowResult, CalculateLiquidationResult, CalculateRepayResult,
         InitLendingMarketParams, InitObligationParams, InitReserveParams, LendingMarket,
         NewReserveCollateralParams, NewReserveLiquidityParams, Obligation, Reserve,
-        ReserveCollateral, ReserveConfig, ReserveLiquidity,
+        ReserveCollateral, ReserveConfig, ReserveConfigKey, ReserveLiquidity,
     },
 };
 use num_traits::FromPrimitive;
@@ -114,13 +114,25 @@ pub fn process_instruction(
         LendingInstruction::WithdrawObligationCollateralAndRedeemReserveCollateral {
             collateral_amount,
         } => {
-            msg!("Instruction: Withdraw Obligation Collateral and Redeem Reserve Collateral ");
+            msg!("Instruction: Withdraw Obligation Collateral and Redeem Reserve Collateral");
             process_withdraw_obligation_collateral_and_redeem_reserve_liquidity(
                 program_id,
                 collateral_amount,
                 accounts,
             )
         }
+        LendingInstruction::UpdateReserveConfig {
+            config_enum,
+            new_value,
+        } => {
+            msg!("Instruction: UpdateReserveConfig");
+            process_update_reserve_config(
+                program_id,
+                ReserveConfigKey::from_u8(config_enum)?,
+                new_value,
+                accounts,
+            )
+        }
     }
 }
 
@@ -1994,6 +2006,68 @@ fn process_withdraw_obligation_collateral_and_redeem_reserve_liquidity(
     )
 }
 
+#[inline(never)] // avoid stack frame limit
+fn process_update_reserve_config(
+    program_id: &Pubkey,
+    config_enum: ReserveConfigKey,
+    new_value: u8,
+    accounts: &[AccountInfo],
+) -> ProgramResult {
+    let account_info_iter = &mut accounts.iter().peekable();
+    let reserve_info = next_account_info(account_info_iter)?;
+    let lending_market_info = next_account_info(account_info_iter)?;
+    let lending_market_authority_info = next_account_info(account_info_iter)?;
+    let lending_market_owner_info = next_account_info(account_info_iter)?;
+
+    let mut reserve = assert_uninitialized::<Reserve>(reserve_info)?;
+    if reserve_info.owner != program_id {
+        msg!(
+            "Reserve provided is not owned by the lending program {} != {}",
+            &reserve_info.owner.to_string(),
+            &program_id.to_string(),
+        );
+        return Err(LendingError::InvalidAccountOwner.into());
+    }
+
+    let lending_market = LendingMarket::unpack(&lending_market_info.data.borrow())?;
+    if lending_market_info.owner != program_id {
+        msg!(
+            "Lending market provided is not owned by the lending program  {} != {}",
+            &lending_market_info.owner.to_string(),
+            &program_id.to_string(),
+        );
+        return Err(LendingError::InvalidAccountOwner.into());
+    }
+    if &lending_market.owner != lending_market_owner_info.key {
+        msg!("Lending market owner does not match the lending market owner provided");
+        return Err(LendingError::InvalidMarketOwner.into());
+    }
+    if !lending_market_owner_info.is_signer {
+        msg!("Lending market owner provided must be a signer");
+        return Err(LendingError::InvalidSigner.into());
+    }
+
+    let authority_signer_seeds = &[
+        lending_market_info.key.as_ref(),
+        &[lending_market.bump_seed],
+    ];
+    let lending_market_authority_pubkey =
+        Pubkey::create_program_address(authority_signer_seeds, program_id)?;
+    if &lending_market_authority_pubkey != lending_market_authority_info.key {
+        msg!(
+            "Derived lending market authority does not match the lending market authority provided"
+        );
+        return Err(LendingError::InvalidMarketAuthority.into());
+    }
+    match config_enum {
+        ReserveConfigKey::LoanToValueRatio => {
+            reserve.config.loan_to_value_ratio = new_value;
+        }
+    };
+    Reserve::pack(reserve, &mut reserve_info.data.borrow_mut())?;
+    Ok(())
+}
+
 fn assert_rent_exempt(rent: &Rent, account_info: &AccountInfo) -> ProgramResult {
     if !rent.is_exempt(account_info.lamports(), account_info.data_len()) {
         msg!(

token-lending/program/src/state/reserve.rs

@@ -613,6 +613,23 @@ pub struct ReserveConfig {
     pub fees: ReserveFees,
 }
 
+/// ReserveConfig configurable values
+#[repr(u8)]
+pub enum ReserveConfigKey {
+    /// Enum to specify LoanToValueRatio
+    LoanToValueRatio = 0,
+}
+
+impl ReserveConfigKey {
+    /// returns the ReserveConfigKey corresponding to the integer
+    pub fn from_u8(value: u8) -> Result<ReserveConfigKey, ProgramError> {
+        match value {
+            0 => Ok(ReserveConfigKey::LoanToValueRatio),
+            _ => Err(LendingError::InvalidConfig.into()),
+        }
+    }
+}
+
 /// Additional fee information on a reserve
 ///
 /// These exist separately from interest accrual fees, and are specifically for the program owner