[PATCH v8 23/25] gpu: nova-core: mm: Add BarUser to struct Gpu and create at boot

[Joel Fernandes <joelagnelf@nvidia.com>]

Add a BarUser field to struct Gpu and eagerly create it during GPU
initialization. The BarUser provides the BAR1 user interface for CPU
access to GPU virtual memory through the GPU's MMU.

The BarUser is initialized using BAR1 PDE base address from GSP static
info, MMU version and BAR1 size obtained from platform device.

Cc: Nikola Djukic <ndjukic@nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs          | 22 +++++++++++++++++++++-
 drivers/gpu/nova-core/gsp/commands.rs |  1 -
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index ba769de2f984..4281487ca52e 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -26,7 +26,12 @@
         commands::GetGspStaticInfoReply,
         Gsp, //
     },
-    mm::GpuMm,
+    mm::{
+        bar_user::BarUser,
+        pagetable::MmuVersion,
+        GpuMm,
+        VramAddress, //
+    },
     num::IntoSafeCast,
     regs,
 };
@@ -36,6 +41,7 @@
 struct BootParams {
     usable_vram_start: u64,
     usable_vram_size: u64,
+    bar1_pde_base: u64,
 }
 
 macro_rules! define_chipset {
@@ -273,6 +279,8 @@ pub(crate) struct Gpu {
     gsp: Gsp,
     /// Static GPU information from GSP.
     gsp_static_info: GetGspStaticInfoReply,
+    /// BAR1 user interface for CPU access to GPU virtual memory.
+    bar_user: BarUser,
 }
 
 impl Gpu {
@@ -286,6 +294,7 @@ pub(crate) fn new<'a>(
         let boot_params: Cell<BootParams> = Cell::new(BootParams {
             usable_vram_start: 0,
             usable_vram_size: 0,
+            bar1_pde_base: 0,
         });
 
         try_pin_init!(Self {
@@ -330,6 +339,7 @@ pub(crate) fn new<'a>(
                 boot_params.set(BootParams {
                     usable_vram_start: usable_vram.start,
                     usable_vram_size: usable_vram.end - usable_vram.start,
+                    bar1_pde_base: info.bar1_pde_base(),
                 });
 
                 info
@@ -346,6 +356,16 @@ pub(crate) fn new<'a>(
                 })?
             },
 
+            // Create BAR1 user interface for CPU access to GPU virtual memory.
+            // Uses the BAR1 PDE base from GSP and full BAR1 size for VA space.
+            bar_user: {
+                let params = boot_params.get();
+                let pdb_addr = VramAddress::new(params.bar1_pde_base);
+                let mmu_version = MmuVersion::from(spec.chipset.arch());
+                let bar1_size = pdev.resource_len(1)?;
+                BarUser::new(pdb_addr, mmu_version, bar1_size)?
+            },
+
             bar: devres_bar,
         })
     }
diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
index 22bd61e2a67e..8b3fa29c57f1 100644
--- a/drivers/gpu/nova-core/gsp/commands.rs
+++ b/drivers/gpu/nova-core/gsp/commands.rs
@@ -235,7 +235,6 @@ pub(crate) fn gpu_name(&self) -> core::result::Result<&str, GpuNameError> {
     }
 
     /// Returns the BAR1 Page Directory Entry base address.
-    #[expect(dead_code)]
     pub(crate) fn bar1_pde_base(&self) -> u64 {
         self.bar1_pde_base
     }
-- 
2.34.1