[PATCH RFC v6 15/26] nova-core: mm: Add GpuMm centralized memory manager

[Joel Fernandes <joelagnelf@nvidia.com>]

Introduce GpuMm as the centralized GPU memory manager that owns:
- Buddy allocator for VRAM allocation.
- PRAMIN window for direct VRAM access.
- TLB manager for translation buffer operations.

This provides clean ownership model where GpuMm provides accessor
methods for its components that can be used for memory management
operations.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs    | 14 +++++++++
 drivers/gpu/nova-core/mm/mod.rs | 55 ++++++++++++++++++++++++++++++++-
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 9b042ef1a308..572e6d4502bc 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -4,8 +4,10 @@
     device,
     devres::Devres,
     fmt,
+    gpu::buddy::GpuBuddyParams,
     pci,
     prelude::*,
+    sizes::{SZ_1M, SZ_4K},
     sync::Arc, //
 };
 
@@ -19,6 +21,7 @@
     fb::SysmemFlush,
     gfw,
     gsp::Gsp,
+    mm::GpuMm,
     regs,
 };
 
@@ -249,6 +252,8 @@ pub(crate) struct Gpu {
     gsp_falcon: Falcon<GspFalcon>,
     /// SEC2 falcon instance, used for GSP boot up and cleanup.
     sec2_falcon: Falcon<Sec2Falcon>,
+    /// GPU memory manager owning memory management resources.
+    mm: GpuMm,
     /// GSP runtime data. Temporarily an empty placeholder.
     #[pin]
     gsp: Gsp,
@@ -281,6 +286,15 @@ pub(crate) fn new<'a>(
 
             sec2_falcon: Falcon::new(pdev.as_ref(), spec.chipset)?,
 
+            // Create GPU memory manager owning memory management resources.
+            // This will be initialized with the usable VRAM region from GSP in a later
+            // patch. For now, we use a placeholder of 1MB.
+            mm: GpuMm::new(devres_bar.clone(), GpuBuddyParams {
+                base_offset_bytes: 0,
+                physical_memory_size_bytes: SZ_1M as u64,
+                chunk_size_bytes: SZ_4K as u64,
+            })?,
+
             gsp <- Gsp::new(pdev),
 
             _: { gsp.boot(pdev, bar, spec.chipset, gsp_falcon, sec2_falcon)? },
diff --git a/drivers/gpu/nova-core/mm/mod.rs b/drivers/gpu/nova-core/mm/mod.rs
index 39635f2d0156..56c72bf51431 100644
--- a/drivers/gpu/nova-core/mm/mod.rs
+++ b/drivers/gpu/nova-core/mm/mod.rs
@@ -8,7 +8,60 @@
 pub(crate) mod pramin;
 pub(crate) mod tlb;
 
-use kernel::sizes::SZ_4K;
+use kernel::{
+    devres::Devres,
+    gpu::buddy::{
+        GpuBuddy,
+        GpuBuddyParams, //
+    },
+    prelude::*,
+    sizes::SZ_4K,
+    sync::Arc, //
+};
+
+use crate::driver::Bar0;
+
+pub(crate) use tlb::Tlb;
+
+/// GPU Memory Manager - owns all core MM components.
+///
+/// Provides centralized ownership of memory management resources:
+/// - [`GpuBuddy`] allocator for VRAM page table allocation.
+/// - [`pramin::Window`] for direct VRAM access.
+/// - [`Tlb`] manager for translation buffer flush operations.
+///
+/// No pinning required, all fields manage their own pinning internally.
+pub(crate) struct GpuMm {
+    buddy: GpuBuddy,
+    pramin: pramin::Window,
+    tlb: Tlb,
+}
+
+impl GpuMm {
+    /// Create a new `GpuMm` object.
+    pub(crate) fn new(bar: Arc<Devres<Bar0>>, buddy_params: GpuBuddyParams) -> Result<Self> {
+        Ok(Self {
+            buddy: GpuBuddy::new(buddy_params)?,
+            pramin: pramin::Window::new(bar.clone())?,
+            tlb: Tlb::new(bar),
+        })
+    }
+
+    /// Access the [`GpuBuddy`] allocator.
+    pub(crate) fn buddy(&self) -> &GpuBuddy {
+        &self.buddy
+    }
+
+    /// Access the [`pramin::Window`].
+    pub(crate) fn pramin(&mut self) -> &mut pramin::Window {
+        &mut self.pramin
+    }
+
+    /// Access the [`Tlb`] manager.
+    pub(crate) fn tlb(&self) -> &Tlb {
+        &self.tlb
+    }
+}
 
 /// Page size in bytes (4 KiB).
 pub(crate) const PAGE_SIZE: usize = SZ_4K;
-- 
2.34.1