Add page table entry and directory structures for MMU version 2 used by Turing/Ampere/Ada GPUs.
Signed-off-by: Joel Fernandes <[email protected]> --- drivers/gpu/nova-core/mm/pagetable/mod.rs | 1 + drivers/gpu/nova-core/mm/pagetable/ver2.rs | 184 +++++++++++++++++++++ 2 files changed, 185 insertions(+) create mode 100644 drivers/gpu/nova-core/mm/pagetable/ver2.rs diff --git a/drivers/gpu/nova-core/mm/pagetable/mod.rs b/drivers/gpu/nova-core/mm/pagetable/mod.rs index bb3a37cc6ca0..787755e89a5b 100644 --- a/drivers/gpu/nova-core/mm/pagetable/mod.rs +++ b/drivers/gpu/nova-core/mm/pagetable/mod.rs @@ -7,6 +7,7 @@ //! - Memory aperture types for PDEs and PTEs #![expect(dead_code)] +pub(crate) mod ver2; use crate::gpu::Architecture; diff --git a/drivers/gpu/nova-core/mm/pagetable/ver2.rs b/drivers/gpu/nova-core/mm/pagetable/ver2.rs new file mode 100644 index 000000000000..d50c3e56d38e --- /dev/null +++ b/drivers/gpu/nova-core/mm/pagetable/ver2.rs @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! MMU v2 page table types for Turing and Ampere GPUs. +//! +//! This module defines MMU version 2 specific types (Turing, Ampere and Ada GPUs). +//! +//! Bit field layouts derived from the NVIDIA OpenRM documentation: +//! `open-gpu-kernel-modules/src/common/inc/swref/published/turing/tu102/dev_mmu.h` + +#![expect(dead_code)] + +use super::{ + AperturePde, + AperturePte, // +}; +use crate::mm::{ + Pfn, + VramAddress, // +}; + +// Page Table Entry (PTE) for MMU v2 - 64-bit entry at level 4. +bitfield! { + pub(crate) struct Pte(u64), "Page Table Entry for MMU v2" { + 0:0 valid as bool, "Entry is valid"; + 2:1 aperture as u8 => AperturePte, "Memory aperture type"; + 3:3 volatile as bool, "Volatile (bypass L2 cache)"; + 4:4 encrypted as bool, "Encryption enabled (Confidential Computing)"; + 5:5 privilege as bool, "Privileged access only"; + 6:6 read_only as bool, "Write protection"; + 7:7 atomic_disable as bool, "Atomic operations disabled"; + 53:8 frame_number_sys as u64 => Pfn, "Frame number for system memory"; + 32:8 frame_number_vid as u64 => Pfn, "Frame number for video memory"; + 35:33 peer_id as u8, "Peer GPU ID for peer memory (0-7)"; + 53:36 comptagline as u32, "Compression tag line bits"; + 63:56 kind as u8, "Surface kind/format"; + } +} + +impl Pte { + /// Create a PTE from a `u64` value. + pub(crate) fn new(val: u64) -> Self { + Self(val) + } + + /// Create a valid PTE for video memory. + pub(crate) fn new_vram(pfn: Pfn, writable: bool) -> Self { + Self::default() + .set_valid(true) + .set_aperture(AperturePte::VideoMemory) + .set_frame_number_vid(pfn) + .set_read_only(!writable) + } + + /// Create an invalid PTE. + pub(crate) fn invalid() -> Self { + Self::default() + } + + /// Get the frame number based on aperture type. + pub(crate) fn frame_number(&self) -> Pfn { + match self.aperture() { + AperturePte::VideoMemory => self.frame_number_vid(), + _ => self.frame_number_sys(), + } + } + + /// Get the raw `u64` value. + pub(crate) fn raw_u64(&self) -> u64 { + self.0 + } +} + +// Page Directory Entry (PDE) for MMU v2 - 64-bit entry at levels 0-2. +bitfield! { + pub(crate) struct Pde(u64), "Page Directory Entry for MMU v2" { + 0:0 valid_inverted as bool, "Valid bit (inverted logic)"; + 2:1 aperture as u8 => AperturePde, "Memory aperture type"; + 3:3 volatile as bool, "Volatile (bypass L2 cache)"; + 5:5 no_ats as bool, "Disable Address Translation Services"; + 53:8 table_frame_sys as u64 => Pfn, "Table frame number for system memory"; + 32:8 table_frame_vid as u64 => Pfn, "Table frame number for video memory"; + 35:33 peer_id as u8, "Peer GPU ID (0-7)"; + } +} + +impl Pde { + /// Create a PDE from a `u64` value. + pub(crate) fn new(val: u64) -> Self { + Self(val) + } + + /// Create a valid PDE pointing to a page table in video memory. + pub(crate) fn new_vram(table_pfn: Pfn) -> Self { + Self::default() + .set_valid_inverted(false) // 0 = valid + .set_aperture(AperturePde::VideoMemory) + .set_table_frame_vid(table_pfn) + } + + /// Create an invalid PDE. + pub(crate) fn invalid() -> Self { + Self::default() + .set_valid_inverted(true) + .set_aperture(AperturePde::Invalid) + } + + /// Check if this PDE is valid. + pub(crate) fn is_valid(&self) -> bool { + !self.valid_inverted() && self.aperture() != AperturePde::Invalid + } + + /// Get the table frame number based on aperture type. + pub(crate) fn table_frame(&self) -> Pfn { + match self.aperture() { + AperturePde::VideoMemory => self.table_frame_vid(), + _ => self.table_frame_sys(), + } + } + + /// Get the VRAM address of the page table. + pub(crate) fn table_vram_address(&self) -> VramAddress { + debug_assert!( + self.aperture() == AperturePde::VideoMemory, + "table_vram_address called on non-VRAM PDE (aperture: {:?})", + self.aperture() + ); + VramAddress::from(self.table_frame_vid()) + } + + /// Get the raw `u64` value of the PDE. + pub(crate) fn raw_u64(&self) -> u64 { + self.0 + } +} + +/// Dual PDE at Level 3 - 128-bit entry of Large/Small Page Table pointers. +/// +/// The dual PDE supports both large (64KB) and small (4KB) page tables. +#[repr(C)] +#[derive(Debug, Clone, Copy, Default)] +pub(crate) struct DualPde { + /// Large/Big Page Table pointer (lower 64 bits). + pub big: Pde, + /// Small Page Table pointer (upper 64 bits). + pub small: Pde, +} + +impl DualPde { + /// Create a dual PDE from raw 128-bit value (two `u64`s). + pub(crate) fn new(big: u64, small: u64) -> Self { + Self { + big: Pde::new(big), + small: Pde::new(small), + } + } + + /// Create a dual PDE with only the small page table pointer set. + /// + /// Note: The big (LPT) portion is set to 0, not `Pde::invalid()`. + /// According to hardware documentation, clearing bit 0 of the 128-bit + /// entry makes the PDE behave as a "normal" PDE. Using `Pde::invalid()` + /// would set bit 0 (valid_inverted), which breaks page table walking. + pub(crate) fn new_small(table_pfn: Pfn) -> Self { + Self { + big: Pde::new(0), + small: Pde::new_vram(table_pfn), + } + } + + /// Check if the small page table pointer is valid. + pub(crate) fn has_small(&self) -> bool { + self.small.is_valid() + } + + /// Check if the big page table pointer is valid. + pub(crate) fn has_big(&self) -> bool { + self.big.is_valid() + } + + /// Get the small page table PFN. + pub(crate) fn small_pfn(&self) -> Pfn { + self.small.table_frame() + } +} -- 2.34.1
