gpu: nvgpu: add support for disabling l3 via DT

On volta the GPU determines whether to do L3 allocation for a mapping by
checking bit 36 of the physical address. So if a mapping should allocate lines
in the L3 this bit must be set.

However, when the physical addresses for 64GB of RAM uses the 36th bit
resulting in a conflict. Thus, add support for disabling l3 support
for SKUs having 64GB of physical memory.

Bug 3486025

Signed-off-by: Debarshi Dutta <ddutta@nvidia.com>
Change-Id: Ic540e754274cf1d9e6625493962699d21509e540
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2661548
Reviewed-by: Brad Griffis <bgriffis@nvidia.com>
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
Tested-by: Brad Griffis <bgriffis@nvidia.com>
GVS: Gerrit_Virtual_Submit

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/gpu/nvgpu/vgpu/gp10b/vgpu_mm_gp10b.c b/drivers/gpu/nvgpu/vgpu/gp10b/vgpu_mm_gp10b.c
index 926f243d..fe28bf21 100644
--- a/drivers/gpu/nvgpu/vgpu/gp10b/vgpu_mm_gp10b.c
+++ b/drivers/gpu/nvgpu/vgpu/gp10b/vgpu_mm_gp10b.c
@@ -1,7 +1,7 @@
 /*
  * Virtualized GPU Memory Management
  *
- * Copyright (c) 2015-2021, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2015-2022, NVIDIA CORPORATION.  All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -178,8 +178,10 @@ u64 vgpu_gp10b_locked_gmmu_map(struct vm_gk20a *vm,
                 p->flags = TEGRA_VGPU_MAP_CACHEABLE;
         if (flags & NVGPU_VM_MAP_IO_COHERENT)
                 p->flags |= TEGRA_VGPU_MAP_IO_COHERENT;
-        if (flags & NVGPU_VM_MAP_L3_ALLOC)
-                p->flags |= TEGRA_VGPU_MAP_L3_ALLOC;
+        if (!nvgpu_is_enabled(g, NVGPU_DISABLE_L3_SUPPORT)) {
+                if (flags & NVGPU_VM_MAP_L3_ALLOC)
+                        p->flags |= TEGRA_VGPU_MAP_L3_ALLOC;
+        }
         if (flags & NVGPU_VM_MAP_PLATFORM_ATOMIC) {
                 p->flags |= TEGRA_VGPU_MAP_PLATFORM_ATOMIC;
         }