[PATCH v11 10/20] gpu: nova-core: mm: Add MMU v2 page table types

[Joel Fernandes]

Add page table entry and directory structures for MMU version 2
used by Turing/Ampere/Ada GPUs.

Cc: Nikola Djukic <ndjukic@xxxxxxxxxx>
Signed-off-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
---
 drivers/gpu/nova-core/mm/pagetable.rs      |   2 +
 drivers/gpu/nova-core/mm/pagetable/ver2.rs | 271 +++++++++++++++++++++
 2 files changed, 273 insertions(+)
 create mode 100644 drivers/gpu/nova-core/mm/pagetable/ver2.rs

diff --git a/drivers/gpu/nova-core/mm/pagetable.rs b/drivers/gpu/nova-core/mm/pagetable.rs
index 637ff43ea83a..f6b184c9b8c8 100644
--- a/drivers/gpu/nova-core/mm/pagetable.rs
+++ b/drivers/gpu/nova-core/mm/pagetable.rs
@@ -8,6 +8,8 @@
 
 #![expect(dead_code)]
 
+pub(super) mod ver2;
+
 use kernel::num::Bounded;
 
 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..8086f1e5abd8
--- /dev/null
+++ b/drivers/gpu/nova-core/mm/pagetable/ver2.rs
@@ -0,0 +1,271 @@
+// 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 kernel::bitfield;
+use kernel::num::Bounded;
+use pin_init::Zeroable;
+
+use super::{
+    AperturePde,
+    AperturePte,
+    PageTableLevel,
+    VaLevelIndex, //
+};
+use crate::mm::{
+    Pfn,
+    VirtualAddress,
+    VramAddress, //
+};
+
+// Bounded to version 2 Pfn bitfield conversions:
+// 25 bits for video memory frame numbers (bits 32:8).
+impl_pfn_bounded!(25);
+// 46 bits for system memory frame numbers (bits 53:8).
+impl_pfn_bounded!(46);
+
+bitfield! {
+    /// MMU v2 49-bit virtual address layout.
+    pub(super) struct VirtualAddressV2(u64) {
+        /// Page offset [11:0].
+        11:0    offset;
+        /// PT index [20:12].
+        20:12   pt_idx;
+        /// PDE0 index [28:21].
+        28:21   pde0_idx;
+        /// PDE1 index [37:29].
+        37:29   pde1_idx;
+        /// PDE2 index [46:38].
+        46:38   pde2_idx;
+        /// PDE3 index [48:47].
+        48:47   pde3_idx;
+    }
+}
+
+impl VirtualAddressV2 {
+    /// Create a [`VirtualAddressV2`] from a [`VirtualAddress`].
+    pub(super) fn new(va: VirtualAddress) -> Self {
+        Self::from_raw(va.raw_u64())
+    }
+}
+
+impl VaLevelIndex for VirtualAddressV2 {
+    fn level_index(&self, level: u64) -> u64 {
+        match level {
+            0 => self.pde3_idx(),
+            1 => self.pde2_idx(),
+            2 => self.pde1_idx(),
+            3 => self.pde0_idx(),
+            4 => self.pt_idx(),
+            _ => 0,
+        }
+    }
+}
+
+/// `PDE` levels for MMU v2 (5-level hierarchy: `PDB` -> `L1` -> `L2` -> `L3` -> `L4`).
+pub(super) const PDE_LEVELS: &[PageTableLevel] = &[
+    PageTableLevel::Pdb,
+    PageTableLevel::L1,
+    PageTableLevel::L2,
+    PageTableLevel::L3,
+];
+
+/// `PTE` level for MMU v2.
+pub(super) const PTE_LEVEL: PageTableLevel = PageTableLevel::L4;
+
+/// Dual `PDE` level for MMU v2 (128-bit entries).
+pub(super) const DUAL_PDE_LEVEL: PageTableLevel = PageTableLevel::L3;
+
+// Page Table Entry (PTE) for MMU v2 - 64-bit entry at level 4.
+bitfield! {
+    /// Page Table Entry for MMU v2.
+    pub(in crate::mm) struct Pte(u64) {
+        /// Entry is valid.
+        0:0     valid;
+        /// Memory aperture type.
+        2:1     aperture => AperturePte;
+        /// Volatile (bypass L2 cache).
+        3:3     volatile;
+        /// Encryption enabled (Confidential Computing).
+        4:4     encrypted;
+        /// Privileged access only.
+        5:5     privilege;
+        /// Write protection.
+        6:6     read_only;
+        /// Atomic operations disabled.
+        7:7     atomic_disable;
+        /// Frame number for system memory.
+        53:8    frame_number_sys => Pfn;
+        /// Frame number for video memory.
+        32:8    frame_number_vid => Pfn;
+        /// Peer GPU ID for peer memory (0-7).
+        35:33   peer_id;
+        /// Compression tag line bits.
+        53:36   comptagline;
+        /// Surface kind/format.
+        63:56   kind;
+    }
+}
+
+impl Pte {
+    /// Create a `PTE` from a `u64` value.
+    pub(super) fn new(val: u64) -> Self {
+        Self::from_raw(val)
+    }
+
+    /// Create a valid `PTE` for video memory.
+    pub(super) fn new_vram(pfn: Pfn, writable: bool) -> Self {
+        Self::zeroed()
+            .with_valid(true)
+            .with_aperture(AperturePte::VideoMemory)
+            .with_frame_number_vid(pfn)
+            .with_read_only(!writable)
+    }
+
+    /// Create an invalid `PTE`.
+    pub(super) fn invalid() -> Self {
+        Self::zeroed()
+    }
+
+    /// Get the frame number based on aperture type.
+    pub(super) fn frame_number(&self) -> Pfn {
+        match self.aperture() {
+            AperturePte::VideoMemory => self.frame_number_vid(),
+            _ => self.frame_number_sys(),
+        }
+    }
+
+    /// Get the raw `u64` value.
+    pub(super) fn raw_u64(&self) -> u64 {
+        self.into_raw()
+    }
+}
+
+// Page Directory Entry (PDE) for MMU v2 - 64-bit entry at levels 0-2.
+bitfield! {
+    /// Page Directory Entry for MMU v2.
+    pub(in crate::mm) struct Pde(u64) {
+        /// Valid bit (inverted logic).
+        0:0     valid_inverted;
+        /// Memory aperture type.
+        2:1     aperture => AperturePde;
+        /// Volatile (bypass L2 cache).
+        3:3     volatile;
+        /// Disable Address Translation Services.
+        5:5     no_ats;
+        /// Table frame number for system memory.
+        53:8    table_frame_sys => Pfn;
+        /// Table frame number for video memory.
+        32:8    table_frame_vid => Pfn;
+        /// Peer GPU ID (0-7).
+        35:33   peer_id;
+    }
+}
+
+impl Pde {
+    /// Create a `PDE` from a `u64` value.
+    pub(super) fn new(val: u64) -> Self {
+        Self::from_raw(val)
+    }
+
+    /// Create a valid `PDE` pointing to a page table in video memory.
+    pub(super) fn new_vram(table_pfn: Pfn) -> Self {
+        Self::zeroed()
+            .with_valid_inverted(false) // 0 = valid
+            .with_aperture(AperturePde::VideoMemory)
+            .with_table_frame_vid(table_pfn)
+    }
+
+    /// Create an invalid `PDE`.
+    pub(super) fn invalid() -> Self {
+        Self::zeroed()
+            .with_valid_inverted(true)
+            .with_aperture(AperturePde::Invalid)
+    }
+
+    /// Check if this `PDE` is valid.
+    pub(super) fn is_valid(&self) -> bool {
+        !self.valid_inverted().into_bool() && self.aperture() != AperturePde::Invalid
+    }
+
+    /// Get the table frame number based on aperture type.
+    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(super) 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(super) fn raw_u64(&self) -> u64 {
+        self.into_raw()
+    }
+}
+
+/// 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)]
+pub(in crate::mm) struct DualPde {
+    /// Large/Big Page Table pointer (lower 64 bits).
+    pub(super) big: Pde,
+    /// Small Page Table pointer (upper 64 bits).
+    pub(super) small: Pde,
+}
+
+
+impl DualPde {
+    /// Create a dual `PDE` from raw 128-bit value (two `u64`s).
+    pub(super) 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(super) 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(super) fn has_small(&self) -> bool {
+        self.small.is_valid()
+    }
+
+    /// Check if the big page table pointer is valid.
+    fn has_big(&self) -> bool {
+        self.big.is_valid()
+    }
+
+    /// Get the small page table `Pfn`.
+    fn small_pfn(&self) -> Pfn {
+        self.small.table_frame()
+    }
+}
-- 
2.34.1