[PATCH v1 08/16] gpu: nova-core: mm: Add MMU v3 page table types

[Joel Fernandes]

Add page table entry and directory structures for MMU version 3 used by
Hopper and later GPUs. The `Pte`, `Pde`, and `DualPde` types each
implement the `PteOps`, `PdeOps`, and `DualPdeOps` traits introduced
earlier in the series, providing the version-agnostic API used by the
forthcoming page-table walker and mapper.

Signed-off-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
---
 drivers/gpu/nova-core/mm/pagetable.rs      |   1 +
 drivers/gpu/nova-core/mm/pagetable/ver3.rs | 421 +++++++++++++++++++++
 2 files changed, 422 insertions(+)
 create mode 100644 drivers/gpu/nova-core/mm/pagetable/ver3.rs

diff --git a/drivers/gpu/nova-core/mm/pagetable.rs b/drivers/gpu/nova-core/mm/pagetable.rs
index df041fc89390..3cc546f94fdb 100644
--- a/drivers/gpu/nova-core/mm/pagetable.rs
+++ b/drivers/gpu/nova-core/mm/pagetable.rs
@@ -9,6 +9,7 @@
 #![expect(dead_code)]
 
 pub(super) mod ver2;
+pub(super) mod ver3;
 
 use kernel::prelude::*;
 
diff --git a/drivers/gpu/nova-core/mm/pagetable/ver3.rs b/drivers/gpu/nova-core/mm/pagetable/ver3.rs
new file mode 100644
index 000000000000..805be90df45d
--- /dev/null
+++ b/drivers/gpu/nova-core/mm/pagetable/ver3.rs
@@ -0,0 +1,421 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! MMU v3 page table types for Hopper and later GPUs.
+//!
+//! This module defines MMU version 3 specific types (Hopper and later GPUs).
+//!
+//! Key differences from MMU v2:
+//! - Unified 40-bit address field for all apertures (v2 had separate sys/vid fields).
+//! - PCF (Page Classification Field) replaces separate privilege/RO/atomic/cache bits.
+//! - KIND field is 4 bits (not 8).
+//! - IS_PTE bit in PDE to support large pages directly.
+//! - No COMPTAGLINE field (compression handled differently in v3).
+//! - No separate ENCRYPTED bit.
+//!
+//! Bit field layouts derived from the NVIDIA OpenRM documentation:
+//! `open-gpu-kernel-modules/src/common/inc/swref/published/hopper/gh100/dev_mmu.h`
+
+#![allow(dead_code)]
+
+use kernel::bitfield;
+use kernel::num::Bounded;
+use kernel::prelude::*;
+use pin_init::Zeroable;
+
+use super::{
+    AperturePde,
+    AperturePte,
+    DualPdeOps,
+    PageTableLevel,
+    PdeOps,
+    PteOps,
+    VaLevelIndex, //
+};
+use crate::mm::{
+    Pfn,
+    VirtualAddress,
+    VramAddress, //
+};
+
+// Bounded to version 3 Pfn conversion.
+impl_pfn_bounded!(40);
+
+bitfield! {
+    /// MMU v3 57-bit virtual address layout.
+    pub(super) struct VirtualAddressV3(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 [55:47].
+        55:47   pde3_idx;
+        /// PDE4 index [56].
+        56:56   pde4_idx;
+    }
+}
+
+impl VirtualAddressV3 {
+    /// Create a [`VirtualAddressV3`] from a [`VirtualAddress`].
+    pub(super) fn new(va: VirtualAddress) -> Self {
+        Self::from_raw(va.into_raw())
+    }
+}
+
+impl VaLevelIndex for VirtualAddressV3 {
+    fn level_index(&self, level: u64) -> u64 {
+        match level {
+            0 => *self.pde4_idx(),
+            1 => *self.pde3_idx(),
+            2 => *self.pde2_idx(),
+            3 => *self.pde1_idx(),
+            4 => *self.pde0_idx(),
+            5 => *self.pt_idx(),
+            _ => 0,
+        }
+    }
+}
+
+/// PDE levels for MMU v3 (6-level hierarchy).
+pub(super) const PDE_LEVELS: &[PageTableLevel] = &[
+    PageTableLevel::Pdb,
+    PageTableLevel::L1,
+    PageTableLevel::L2,
+    PageTableLevel::L3,
+    PageTableLevel::L4,
+];
+
+/// PTE level for MMU v3.
+pub(super) const PTE_LEVEL: PageTableLevel = PageTableLevel::L5;
+
+/// Dual PDE level for MMU v3 (128-bit entries).
+pub(super) const DUAL_PDE_LEVEL: PageTableLevel = PageTableLevel::L4;
+
+bitfield! {
+    /// Page Classification Field for PTEs (5 bits) in MMU v3.
+    pub(in crate::mm) struct PtePcf(u8) {
+        /// Bypass L2 cache (0=cached, 1=bypass).
+        0:0     uncached;
+        /// Access counting disabled (0=enabled, 1=disabled).
+        1:1     acd;
+        /// Read-only access (0=read-write, 1=read-only).
+        2:2     read_only;
+        /// Atomics disabled (0=enabled, 1=disabled).
+        3:3     no_atomic;
+        /// Privileged access only (0=regular, 1=privileged).
+        4:4     privileged;
+    }
+}
+
+impl PtePcf {
+    /// Create PCF for read-write mapping (cached, no atomics, regular mode).
+    fn rw() -> Self {
+        Self::zeroed().with_no_atomic(true)
+    }
+
+    /// Create PCF for read-only mapping (cached, no atomics, regular mode).
+    fn ro() -> Self {
+        Self::zeroed().with_read_only(true).with_no_atomic(true)
+    }
+
+    /// Get the raw `u8` value.
+    fn raw_u8(&self) -> u8 {
+        self.into_raw()
+    }
+}
+
+impl From<Bounded<u64, 5>> for PtePcf {
+    fn from(val: Bounded<u64, 5>) -> Self {
+        Self::from_raw(u8::from(val))
+    }
+}
+
+impl From<PtePcf> for Bounded<u64, 5> {
+    fn from(pcf: PtePcf) -> Self {
+        Bounded::from_expr(u64::from(pcf.into_raw()) & 0x1F)
+    }
+}
+
+bitfield! {
+    /// Page Classification Field for PDEs (3 bits) in MMU v3.
+    ///
+    /// Controls Address Translation Services (ATS) and caching.
+    pub(in crate::mm) struct PdePcf(u8) {
+        /// Bypass L2 cache (0=cached, 1=bypass).
+        0:0     uncached;
+        /// ATS disabled (0=enabled, 1=disabled).
+        1:1     no_ats;
+    }
+}
+
+impl PdePcf {
+    /// Create PCF for cached mapping with ATS enabled (default).
+    fn cached() -> Self {
+        Self::zeroed()
+    }
+
+    /// Get the raw `u8` value.
+    fn raw_u8(&self) -> u8 {
+        self.into_raw()
+    }
+}
+
+impl From<Bounded<u64, 3>> for PdePcf {
+    fn from(val: Bounded<u64, 3>) -> Self {
+        Self::from_raw(u8::from(val))
+    }
+}
+
+impl From<PdePcf> for Bounded<u64, 3> {
+    fn from(pcf: PdePcf) -> Self {
+        Bounded::from_expr(u64::from(pcf.into_raw()) & 0x7)
+    }
+}
+
+bitfield! {
+    /// Page Table Entry for MMU v3.
+    pub(in crate::mm) struct Pte(u64) {
+        /// Entry is valid.
+        0:0     valid;
+        /// Memory aperture type.
+        2:1     aperture => AperturePte;
+        /// Page Classification Field.
+        7:3     pcf => PtePcf;
+        /// Surface kind (4 bits, 0x0=pitch, 0xF=invalid).
+        11:8    kind;
+        /// Physical frame number (for all apertures).
+        51:12   frame_number => Pfn;
+        /// Peer GPU ID for peer memory (0-7).
+        63:61   peer_id;
+    }
+}
+
+impl PteOps for Pte {
+    fn from_raw(val: u64) -> Self {
+        Self::from_raw(val)
+    }
+
+    fn invalid() -> Self {
+        Self::zeroed()
+    }
+
+    fn new(aperture: AperturePte, pfn: Pfn, writable: bool) -> Self {
+        let pcf = match (aperture, writable) {
+            (AperturePte::VideoMemory, true) => PtePcf::rw(),
+            (AperturePte::VideoMemory, false) => PtePcf::ro(),
+            // Sysmem PTEs use uncached+no_atomic PCF for cache coherency.
+            (AperturePte::SystemCoherent, true) => PtePcf::zeroed()
+                .with_uncached(true)
+                .with_no_atomic(true),
+            (AperturePte::SystemCoherent, false) => PtePcf::zeroed()
+                .with_uncached(true)
+                .with_no_atomic(true)
+                .with_read_only(true),
+            (AperturePte::PeerMemory | AperturePte::SystemNonCoherent, _) => {
+                kernel::pr_warn!("MMU v3 PTE aperture {:?} not supported\n", aperture);
+                return Self::invalid();
+            }
+        };
+        Self::zeroed()
+            .with_valid(true)
+            .with_aperture(aperture)
+            .with_pcf(pcf)
+            .with_frame_number(pfn)
+    }
+
+    fn is_valid(&self) -> bool {
+        self.valid().into_bool()
+    }
+
+    fn frame_number(&self) -> Pfn {
+        Pte::frame_number(*self)
+    }
+}
+
+bitfield! {
+    /// Page Directory Entry for MMU v3 (Hopper+).
+    ///
+    /// ## Note
+    ///
+    /// v3 uses a unified 40-bit address field (v2 had separate sys/vid address fields).
+    pub(in crate::mm) struct Pde(u64) {
+        /// Entry is a PTE (0=PDE, 1=large page PTE).
+        0:0     is_pte;
+        /// Memory aperture type.
+        2:1     aperture => AperturePde;
+        /// Page Classification Field (3 bits for PDE).
+        5:3     pcf => PdePcf;
+        /// Table frame number (40-bit unified address).
+        51:12   table_frame => Pfn;
+    }
+}
+
+impl PdeOps for Pde {
+    fn from_raw(val: u64) -> Self {
+        Self::from_raw(val)
+    }
+
+    fn new(aperture: AperturePde, table_pfn: Pfn) -> Self {
+        match aperture {
+            AperturePde::VideoMemory => Self::zeroed()
+                .with_is_pte(false)
+                .with_aperture(aperture)
+                .with_table_frame(table_pfn),
+            AperturePde::Invalid
+            | AperturePde::SystemCoherent
+            | AperturePde::SystemNonCoherent => {
+                kernel::pr_warn!("MMU v3 PDE aperture {:?} not supported\n", aperture);
+                Self::invalid()
+            }
+        }
+    }
+
+    fn invalid() -> Self {
+        Self::zeroed().with_aperture(AperturePde::Invalid)
+    }
+
+    fn is_valid(&self) -> bool {
+        Pde::aperture(*self) != AperturePde::Invalid
+    }
+
+    fn aperture(&self) -> AperturePde {
+        Pde::aperture(*self)
+    }
+
+    fn table_vram_address(&self) -> VramAddress {
+        debug_assert!(
+            Pde::aperture(*self) == AperturePde::VideoMemory,
+            "table_vram_address called on non-VRAM PDE (aperture: {:?})",
+            Pde::aperture(*self)
+        );
+        VramAddress::from(self.table_frame())
+    }
+}
+
+bitfield! {
+    /// Big Page Table pointer in Dual PDE (MMU v3).
+    ///
+    /// 64-bit lower word of the 128-bit Dual PDE.
+    pub(super) struct DualPdeBig(u64) {
+        /// Entry is a PTE (for large pages).
+        0:0     is_pte;
+        /// Memory aperture type.
+        2:1     aperture => AperturePde;
+        /// Page Classification Field.
+        5:3     pcf => PdePcf;
+        /// Table frame (table address 256-byte aligned).
+        51:8    table_frame;
+    }
+}
+
+impl DualPdeBig {
+    /// Create an invalid big page table pointer.
+    fn invalid() -> Self {
+        Self::zeroed().with_aperture(AperturePde::Invalid)
+    }
+
+    /// Create a valid big PDE pointing to a page table in the given aperture.
+    fn new(aperture: AperturePde, table_addr: VramAddress) -> Result<Self> {
+        // Big page table addresses must be 256-byte aligned (shift 8).
+        if table_addr.raw() & 0xFF != 0 {
+            return Err(EINVAL);
+        }
+        let table_frame = Bounded::from_expr(table_addr.raw() >> 8);
+        match aperture {
+            AperturePde::VideoMemory => Ok(Self::zeroed()
+                .with_is_pte(false)
+                .with_aperture(aperture)
+                .with_table_frame(table_frame)),
+            AperturePde::Invalid
+            | AperturePde::SystemCoherent
+            | AperturePde::SystemNonCoherent => {
+                kernel::pr_warn!("MMU v3 DualPdeBig aperture {:?} not supported\n", aperture);
+                Ok(Self::invalid())
+            }
+        }
+    }
+
+    /// Check if this big PDE is valid.
+    fn is_valid(&self) -> bool {
+        self.aperture() != AperturePde::Invalid
+    }
+
+    /// Get the VRAM address of the big page table.
+    fn table_vram_address(&self) -> VramAddress {
+        debug_assert!(
+            self.aperture() == AperturePde::VideoMemory,
+            "table_vram_address called on non-VRAM DualPdeBig (aperture: {:?})",
+            self.aperture()
+        );
+        VramAddress::new(*self.table_frame() << 8)
+    }
+}
+
+/// Dual PDE at Level 4 for MMU v3 - 128-bit entry.
+///
+/// Contains both big (64KB) and small (4KB) page table pointers:
+/// - Lower 64 bits: Big Page Table pointer.
+/// - Upper 64 bits: Small Page Table pointer.
+///
+/// ## Note
+///
+/// The big and small page table pointers have different address layouts:
+/// - Big address = field value << 8 (256-byte alignment).
+/// - Small address = field value << 12 (4KB alignment).
+///
+/// This is why `DualPdeBig` is a separate type from `Pde`.
+#[repr(C)]
+#[derive(Debug, Clone, Copy)]
+pub(in crate::mm) struct DualPde {
+    /// Big Page Table pointer.
+    pub(super) big: DualPdeBig,
+    /// Small Page Table pointer.
+    pub(super) small: Pde,
+}
+
+// SAFETY: Both `DualPdeBig` and `Pde` fields are `Zeroable` (bitfield types are Zeroable).
+unsafe impl Zeroable for DualPde {}
+
+impl DualPde {
+    /// Check if the big page table pointer is valid.
+    fn has_big(&self) -> bool {
+        self.big.is_valid()
+    }
+}
+
+impl DualPdeOps for DualPde {
+    fn from_raw(big: u64, small: u64) -> Self {
+        Self {
+            big: DualPdeBig::from_raw(big),
+            small: PdeOps::from_raw(small),
+        }
+    }
+
+    fn new_small(table_pfn: Pfn) -> Self {
+        Self {
+            big: DualPdeBig::invalid(),
+            small: PdeOps::new(AperturePde::VideoMemory, table_pfn),
+        }
+    }
+
+    fn has_small(&self) -> bool {
+        PdeOps::is_valid(&self.small)
+    }
+
+    fn small_vram_address(&self) -> VramAddress {
+        PdeOps::table_vram_address(&self.small)
+    }
+
+    fn big_raw_u64(&self) -> u64 {
+        self.big.into_raw()
+    }
+
+    fn small_raw_u64(&self) -> u64 {
+        self.small.into_raw()
+    }
+}
-- 
2.34.1