rvm-memory

Guest physical address space management for the RVM microhypervisor.

Provides safe abstractions over stage-2 page table mappings with capability-gated access. Each partition has an independent guest physical address space. All mapping operations are recorded in the witness trail. Memory regions can be shared between partitions with explicit grants.

Key Types and Functions

• MemoryRegion -- descriptor: guest base, host base, page count, permissions, owner
• MemoryPermissions -- RWX permission flags with constants (READ_ONLY, READ_WRITE, READ_EXECUTE)
• validate_region(region) -- checks alignment, page count, and permission validity
• regions_overlap(a, b) -- detects overlapping regions within the same partition
• PAGE_SIZE -- 4 KiB page size constant

Example

use rvm_memory::{MemoryRegion, MemoryPermissions, validate_region, PAGE_SIZE};
use rvm_types::{GuestPhysAddr, PhysAddr, PartitionId};

let region = MemoryRegion {
    guest_base: GuestPhysAddr::new(0x8000_0000),
    host_base: PhysAddr::new(0x4000_0000),
    page_count: 16,
    permissions: MemoryPermissions::READ_WRITE,
    owner: PartitionId::new(1),
};
assert!(validate_region(&region).is_ok());

Design Constraints

• DC-15: #![no_std], #![forbid(unsafe_code)], #![deny(missing_docs)]
• ADR-138: capability-gated mappings; witness-logged operations

Workspace Dependencies

• rvm-types
• rvm-hal
• rvm-partition
• rvm-witness