Function finalize_leaf

crates/virtual-machine/src/cpu/mmu.rs:101–185

(
    pte: u64,
    vaddr: u64,
    level: usize,
    priv_mode: PrivilegeMode,
    sum: u64,
    mxr: u64,
    is_write: bool,
    is_execute: bool,
    pmpcfg0: u64,
    pmpaddr0: u64,
)

        Self {
            satp: 0,
            entries: [TlbEntry {
                valid: false,
                vpn: 0,
                pte: 0,
                level: 0,
            }; TLB_ENTRIES],
        }
    }

    /// Invalidate every entry. Called on sfence.vma.
    pub fn flush(&mut self) {
        for e in &mut self.entries {
            e.valid = false;
        }
    }

    // Drop all entries if the active address space (satp) changed.
    fn sync_satp(&mut self, satp: u64) {
        if self.satp != satp {
            self.satp = satp;
            self.flush();
        }
    }

    pub(crate) fn lookup(&self, vpn: u64) -> Option<(u64, usize)> {
        let e = &self.entries[(vpn as usize) & (TLB_ENTRIES - 1)];
        if e.valid && e.vpn == vpn {
            Some((e.pte, e.level))
        } else {
            None
        }
    }

    fn insert(&mut self, vpn: u64, pte: u64, level: usize) {
        self.entries[(vpn as usize) & (TLB_ENTRIES - 1)] = TlbEntry {
            valid: true,
            vpn,
            pte,
            level,
        };
    }
}

// Check a leaf PTE and build the physical address (permission/privilege/superpage/
// PMP). Shared by the walk and a TLB hit; touches no memory and no A/D bits.
pub(crate) fn finalize_leaf(
    pte: u64,
    vaddr: u64,
    level: usize,
    ctx: TranslationContext,
    access: AccessKind,
) -> Result<u64, VmError> {
    let sum = (ctx.mstatus >> 18) & 1;
    let mxr = (ctx.mstatus >> 19) & 1;
    let r = (pte >> 1) & 1;
    let w = (pte >> 2) & 1;
    let x = (pte >> 3) & 1;
    let u_bit = (pte >> 4) & 1;