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Introduce PHYS_MEM_VADDR_RANGE

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Ruihan Li
2024-04-06 23:56:19 +08:00
committed by Tate, Hongliang Tian
parent 02e4cdc80e
commit 849c6e3259
1 changed files with 28 additions and 8 deletions
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36
framework/aster-frame/src/vm/mod.rs
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@ -20,6 +20,7 @@ pub(crate) mod page_table;
mod space; mod space;
use alloc::{borrow::ToOwned, vec::Vec}; use alloc::{borrow::ToOwned, vec::Vec};
use core::ops::Range;
use spin::Once; use spin::Once;
@ -48,22 +49,41 @@ pub const PAGE_SIZE: usize = 0x1000;
/// for the rationale. /// for the rationale.
pub const MAX_USERSPACE_VADDR: Vaddr = 0x0000_8000_0000_0000 - PAGE_SIZE; pub const MAX_USERSPACE_VADDR: Vaddr = 0x0000_8000_0000_0000 - PAGE_SIZE;
/// Start of the kernel address space. /// The base address of the direct mapping of physical memory.
///
/// This is the _lowest_ address of the x86-64's _high_ canonical addresses.
///
/// This is also the base address of the direct mapping of all physical
/// memory in the kernel address space.
pub(crate) const PHYS_MEM_BASE_VADDR: Vaddr = 0xffff_8000_0000_0000; pub(crate) const PHYS_MEM_BASE_VADDR: Vaddr = 0xffff_8000_0000_0000;
/// The maximum size of the direct mapping of physical memory.
///
/// This size acts as a cap. If the actual memory size exceeds this value,
/// the remaining memory cannot be included in the direct mapping because
/// the maximum size of the direct mapping is limited by this value. On
/// the other hand, if the actual memory size is smaller, the direct
/// mapping can shrink to save memory consumption due to the page table.
///
/// We do not currently have APIs to manually map MMIO pages, so we have
/// to rely on the direct mapping to perform MMIO operations. Therefore,
/// we set the maximum size to 127 TiB, which makes some surprisingly
/// high MMIO addresses usable (e.g., `0x7000_0000_7004` for VirtIO
/// devices in the TDX environment) and leaves the last 1 TiB for other
/// uses (e.g., the kernel code starting at [`kernel_loaded_offset()`]).
pub(crate) const PHYS_MEM_MAPPING_MAX_SIZE: usize = 127 << 40;
/// The address range of the direct mapping of physical memory.
///
/// This range is constructed based on [`PHYS_MEM_BASE_VADDR`] and
/// [`PHYS_MEM_MAPPING_MAX_SIZE`].
pub(crate) const PHYS_MEM_VADDR_RANGE: Range<Vaddr> =
PHYS_MEM_BASE_VADDR..(PHYS_MEM_BASE_VADDR + PHYS_MEM_MAPPING_MAX_SIZE);
/// The kernel code is linear mapped to this address. /// The kernel code is linear mapped to this address.
/// ///
/// FIXME: This offset should be randomly chosen by the loader or the /// FIXME: This offset should be randomly chosen by the loader or the
/// boot compatibility layer. But we disabled it because the framework /// boot compatibility layer. But we disabled it because the framework
/// doesn't support relocatable kernel yet. /// doesn't support relocatable kernel yet.
pub fn kernel_loaded_offset() -> usize { pub const fn kernel_loaded_offset() -> usize {
0xffff_ffff_8000_0000 0xffff_ffff_8000_0000
} }
const_assert!(PHYS_MEM_VADDR_RANGE.end < kernel_loaded_offset());
/// Get physical address trait /// Get physical address trait
pub trait HasPaddr { pub trait HasPaddr {
@ -71,7 +91,7 @@ pub trait HasPaddr {
} }
pub fn vaddr_to_paddr(va: Vaddr) -> Option<Paddr> { pub fn vaddr_to_paddr(va: Vaddr) -> Option<Paddr> {
if (PHYS_MEM_BASE_VADDR..=kernel_loaded_offset()).contains(&va) { if PHYS_MEM_VADDR_RANGE.contains(&va) {
// can use offset to get the physical address // can use offset to get the physical address
Some(va - PHYS_MEM_BASE_VADDR) Some(va - PHYS_MEM_BASE_VADDR)
} else { } else {