[PATCH v2 10/12] gpu: nova-core: mm: Add GpuMm centralized memory manager

[Eliot Courtney <ecourtney@nvidia.com>]

From: Joel Fernandes <joelagnelf@nvidia.com>

Introduce GpuMm as the centralized GPU memory manager. At this point in
the series, GpuMm only owns the PRAMIN window for direct VRAM access;
the buddy allocator and TLB manager are added later when those backing
types become available.

This provides a clean ownership model where GpuMm provides accessor
methods for its components that can be used for memory management
operations, and lets follow-on patches (such as the PRAMIN aperture
self-tests) reference `pramin_mut()` cleanly.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
[ecourtney: squash the total VRAM end patch, drop its dev_info print]
[ecourtney: take the maximum FB limit before adding one, fail with EINVAL]
[ecourtney: rebase for the Bar0 lifetime and ownership changes, drop Arcs]
[ecourtney: source the chipset through gsp_resources]
[ecourtney: build the VRAM region in new(), pramin() becomes pramin_mut()]
[ecourtney: declare mm before gsp_resources, doc wording cleanups]
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs             | 18 +++++++++++++++-
 drivers/gpu/nova-core/gsp/commands.rs    |  4 ++++
 drivers/gpu/nova-core/gsp/fw/commands.rs |  5 +++++
 drivers/gpu/nova-core/mm.rs              | 35 ++++++++++++++++++++++++++++++++
 4 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 42a4cd7971fa..e29e07488e78 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -29,6 +29,10 @@
         Gsp,
         GspBootContext, //
     },
+    mm::{
+        GpuMm,
+        VramAddress, //
+    },
     regs,
     vgpu::VgpuManager, //
 };
@@ -283,6 +287,11 @@ pub(crate) struct Gpu<'gpu> {
     spec: Spec,
     /// Static GPU information as provided by the GSP.
     gsp_static_info: GetGspStaticInfoReply,
+    /// GPU memory manager owning memory management resources.
+    ///
+    /// Must be kept declared *before* `gsp_resources`, so that its components are dropped while
+    /// the GSP is still operational.
+    mm: GpuMm<'gpu>,
     /// GSP and its resources.
     #[pin]
     gsp_resources: GspResources<'gpu>,
@@ -410,7 +419,14 @@ pub(crate) fn new(
                 }
 
                 info
-            }
+            },
+
+            // Create GPU memory manager owning memory management resources.
+            mm: GpuMm::new(
+                bar,
+                gsp_resources.spec.chipset,
+                VramAddress::from_raw(gsp_static_info.total_fb_end),
+            )?,
         })
     }
 }
diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
index ffc25fd8c47b..eea1c9ed4684 100644
--- a/drivers/gpu/nova-core/gsp/commands.rs
+++ b/drivers/gpu/nova-core/gsp/commands.rs
@@ -216,6 +216,8 @@ pub(crate) struct GetGspStaticInfoReply {
     gpu_name: [u8; 64],
     /// Usable FB (VRAM) regions for driver memory allocation.
     pub(crate) usable_fb_regions: KVec<Range<u64>>,
+    /// Exclusive end of the FB physical address space.
+    pub(crate) total_fb_end: u64,
 }
 
 impl MessageFromGsp for GetGspStaticInfoReply {
@@ -231,10 +233,12 @@ fn read(
         for region in msg.usable_fb_regions() {
             usable_fb_regions.push(region, GFP_KERNEL)?;
         }
+        let total_fb_end = msg.total_fb_end().ok_or(EINVAL)?;
 
         Ok(GetGspStaticInfoReply {
             gpu_name: msg.gpu_name_str(),
             usable_fb_regions,
+            total_fb_end,
         })
     }
 }
diff --git a/drivers/gpu/nova-core/gsp/fw/commands.rs b/drivers/gpu/nova-core/gsp/fw/commands.rs
index 6dc31d1bf5ae..6e85442a4b13 100644
--- a/drivers/gpu/nova-core/gsp/fw/commands.rs
+++ b/drivers/gpu/nova-core/gsp/fw/commands.rs
@@ -165,6 +165,11 @@ pub(crate) fn usable_fb_regions(&self) -> impl Iterator<Item = Range<u64>> + '_
             }
         })
     }
+
+    /// Computes the exclusive end of the FB physical address space.
+    pub(crate) fn total_fb_end(&self) -> Option<u64> {
+        self.fb_regions().map(|reg| reg.limit).max()?.checked_add(1)
+    }
 }
 
 // SAFETY: Padding is explicit and will not contain uninitialized data.
diff --git a/drivers/gpu/nova-core/mm.rs b/drivers/gpu/nova-core/mm.rs
index ef5b1cad56c3..58dce211a337 100644
--- a/drivers/gpu/nova-core/mm.rs
+++ b/drivers/gpu/nova-core/mm.rs
@@ -19,10 +19,45 @@
     },
 };
 
+use crate::{
+    driver::Bar0,
+    gpu::Chipset, //
+};
+
 mod hal;
 mod pramin;
 mod regs;
 
+/// GPU Memory Manager - owns all core MM components.
+///
+/// Provides centralized ownership of memory management resources:
+/// - [`pramin::Pramin`] for direct VRAM access.
+pub(crate) struct GpuMm<'gpu> {
+    pramin: pramin::Pramin<'gpu>,
+}
+
+impl<'gpu> GpuMm<'gpu> {
+    /// Creates the GPU memory manager.
+    pub(crate) fn new(
+        bar: Bar0<'gpu>,
+        chipset: Chipset,
+        total_fb_end: VramAddress,
+    ) -> Result<Self> {
+        // PRAMIN covers all physical VRAM (including GSP-reserved areas
+        // above the usable region, e.g. the BAR1 page directory).
+        let vram_region = VramAddress::ZERO..total_fb_end;
+
+        Ok(Self {
+            pramin: pramin::Pramin::new(bar, chipset, vram_region)?,
+        })
+    }
+
+    /// Access the [`pramin::Pramin`].
+    fn pramin_mut(&mut self) -> &mut pramin::Pramin<'gpu> {
+        &mut self.pramin
+    }
+}
+
 /// Physical VRAM address in GPU video memory.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 #[repr(transparent)]

-- 
2.55.0