[PATCH RFC v6 09/26] nova-core: mm: Add common memory management types

[Joel Fernandes <joelagnelf@nvidia.com>]

Add foundational types for GPU memory management. These types are used
throughout the nova memory management subsystem for page table
operations, address translation, and memory allocation.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 drivers/gpu/nova-core/mm/mod.rs | 147 ++++++++++++++++++++++++++++++++
 1 file changed, 147 insertions(+)

diff --git a/drivers/gpu/nova-core/mm/mod.rs b/drivers/gpu/nova-core/mm/mod.rs
index 7a5dd4220c67..b57016d453ce 100644
--- a/drivers/gpu/nova-core/mm/mod.rs
+++ b/drivers/gpu/nova-core/mm/mod.rs
@@ -2,4 +2,151 @@
 
 //! Memory management subsystems for nova-core.
 
+#![expect(dead_code)]
+
 pub(crate) mod pramin;
+
+use kernel::sizes::SZ_4K;
+
+/// Page size in bytes (4 KiB).
+pub(crate) const PAGE_SIZE: usize = SZ_4K;
+
+bitfield! {
+    pub(crate) struct VramAddress(u64), "Physical VRAM address in GPU video memory" {
+        11:0    offset          as u64, "Offset within 4KB page";
+        63:12   frame_number    as u64 => Pfn, "Physical frame number";
+    }
+}
+
+impl VramAddress {
+    /// Create a new VRAM address from a raw value.
+    pub(crate) const fn new(addr: u64) -> Self {
+        Self(addr)
+    }
+
+    /// Get the raw address value as `usize` (useful for MMIO offsets).
+    pub(crate) const fn raw(&self) -> usize {
+        self.0 as usize
+    }
+
+    /// Get the raw address value as `u64`.
+    pub(crate) const fn raw_u64(&self) -> u64 {
+        self.0
+    }
+}
+
+impl From<Pfn> for VramAddress {
+    fn from(pfn: Pfn) -> Self {
+        Self::default().set_frame_number(pfn)
+    }
+}
+
+bitfield! {
+    pub(crate) struct VirtualAddress(u64), "Virtual address in GPU address space" {
+        11:0    offset          as u64, "Offset within 4KB page";
+        20:12   l4_index        as u64, "Level 4 index (PTE)";
+        29:21   l3_index        as u64, "Level 3 index (Dual PDE)";
+        38:30   l2_index        as u64, "Level 2 index";
+        47:39   l1_index        as u64, "Level 1 index";
+        56:48   l0_index        as u64, "Level 0 index (PDB)";
+        63:12   frame_number    as u64 => Vfn, "Virtual frame number";
+    }
+}
+
+impl VirtualAddress {
+    /// Create a new virtual address from a raw value.
+    #[expect(dead_code)]
+    pub(crate) const fn new(addr: u64) -> Self {
+        Self(addr)
+    }
+
+    /// Get the page table index for a given level.
+    pub(crate) fn level_index(&self, level: u64) -> u64 {
+        match level {
+            0 => self.l0_index(),
+            1 => self.l1_index(),
+            2 => self.l2_index(),
+            3 => self.l3_index(),
+            4 => self.l4_index(),
+            _ => 0,
+        }
+    }
+}
+
+impl From<Vfn> for VirtualAddress {
+    fn from(vfn: Vfn) -> Self {
+        Self::default().set_frame_number(vfn)
+    }
+}
+
+/// Physical Frame Number.
+///
+/// Represents a physical page in VRAM.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub(crate) struct Pfn(u64);
+
+impl Pfn {
+    /// Create a new PFN from a frame number.
+    pub(crate) const fn new(frame_number: u64) -> Self {
+        Self(frame_number)
+    }
+
+    /// Get the raw frame number.
+    pub(crate) const fn raw(self) -> u64 {
+        self.0
+    }
+}
+
+impl From<VramAddress> for Pfn {
+    fn from(addr: VramAddress) -> Self {
+        addr.frame_number()
+    }
+}
+
+impl From<u64> for Pfn {
+    fn from(val: u64) -> Self {
+        Self(val)
+    }
+}
+
+impl From<Pfn> for u64 {
+    fn from(pfn: Pfn) -> Self {
+        pfn.0
+    }
+}
+
+/// Virtual Frame Number.
+///
+/// Represents a virtual page in GPU address space.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub(crate) struct Vfn(u64);
+
+impl Vfn {
+    /// Create a new VFN from a frame number.
+    pub(crate) const fn new(frame_number: u64) -> Self {
+        Self(frame_number)
+    }
+
+    /// Get the raw frame number.
+    pub(crate) const fn raw(self) -> u64 {
+        self.0
+    }
+}
+
+impl From<VirtualAddress> for Vfn {
+    fn from(addr: VirtualAddress) -> Self {
+        addr.frame_number()
+    }
+}
+
+impl From<u64> for Vfn {
+    fn from(val: u64) -> Self {
+        Self(val)
+    }
+}
+
+impl From<Vfn> for u64 {
+    fn from(vfn: Vfn) -> Self {
+        vfn.0
+    }
+}
-- 
2.34.1